ХХ Симпозиум по геохимии изотопов им. Виноградова А.П.
12-14 ноября 2013 года
1. INVESTIGATION OF PRODUCTION OF THE THERAPEUTIC RADIOISOTOPE 165ER BY PROTON INDUCED REACTIONS ON ERBIUM
IN COMPARISON WITH OTHER PRODUCTION ROUTES
Tárkányi F., Takács S., Ditrói F., Király B., Hermanne A., Baba M., Ohtsuki T., Kovalev S.F., Ignatyuk A.V.
Applied Radiation and Isotopes. 2009. Т. 67. № 2. С. 243-247.
2. LIMITATION OF THE LONG-LIVED
121
TE CONTAMINANT IN PRODUCTION OF 123I THROUGH THE 124XE(P,X) ROUTE
Hermanne A., Adam Rebeles R., Tarkanyi F., Takacs S., Ignatyuk A., Spellerberg S., Schweikert R.
Applied Radiation and Isotopes. 2011. Т. 69. № 2. С. 358-368
3. HIGH YIELD PRODUCTION OF THE MEDICAL RADIOISOTOPE 167TM BY THE 167ER(D,2N) REACTION
Hermanne A., Adam Rebeles R., Tárkányi F., Takács S., Spahn I., Ignatyuk A.V.
Applied Radiation and Isotopes. 2011. Т. 69. № 2. С. 475-481.
4. Zaichick S., Zaichick V.
TRACE ELEMENTS OF NORMAL, BENIGN HYPERTROPHIC AND CANCEROUS TISSUES OF THE HUMAN PROSTATE GLAND
INVESTIGATED BY NEUTRON ACTIVATION ANALYSIS//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 81-87.
5. Tárkányi F., Takács S., Ditrói F., Hermanne A., Spahn I., Ignatyuk A.V.
ACTIVATION CROSS-SECTIONS OF PROTON INDUCED NUCLEAR REACTIONS ON THULIUM IN THE 20-45MEV ENERGY RANGE//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 309-314
6. Al-Abyad M., Abdel-Hamid A.S., Seddik U., Tárkányi F., Ditrói F., Takács S., Bashter I.I.
CROSS-SECTION MEASUREMENTS AND NUCLEAR MODEL CALCULATION FOR PROTON INDUCED NUCLEAR REACTION ON
ZIRCONIUM//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 257-262.
7. Krmar M., Jovančević N., Nikolić D.
MEASUREMENT OF56FE ACTIVITY PRODUCED IN INELASTIC SCATTERING OF NEUTRONS CREATED BY COSMIC MUONS IN AN
IRON SHIELD//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 269-273
8. Chao J.H., Lee H.P., Lee M.C., Chiu Y.J.
DEPOSITION OF BERYLLIUM-7 IN HSINCHU, TAIWAN//
Applied Radiation and Isotopes. 2012. Т. 70. № 2. С. 415-422
9. Rossouw D.D., Breeman W.A.P.
SCALED-UP RADIOLABELLING OF DOTATATE WITH68GA ELUTED FROM A SNO2-BASED68GE/68GA GENERATOR//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 171-175.
10. Zlatopolskiy B.D., Kandler R., Neumaier B., Mottaghy F.M.
C-(4-[18F]FLUOROPHENYL)-N-PHENYL NITRONE: A NOVEL18F-LABELED BUILDING BLOCK FOR METAL FREE
[3+2]CYCLOADDITION//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 184-192.
11. Wong R., Iwata R., Furumoto S., Ishikawa Y., Saiki H., Ozeki E.
REACTIVITY OF ELECTROCHEMICALLY CONCENTRATED ANHYDROUS [18F]FLUORIDE FOR MICROFLUIDIC RADIOSYNTHESIS
OF18F-LABELED COMPOUNDS//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 193-199
12. Koźmiński P., Gniazdowska E., Fuks L., Kowalska S.
'2+1' TRICARBONYLTECHNETIUM(I)/TRICARBONYLRHENIUM(I) MIXED-LIGAND COMPLEXES WITH METHYL THIOSALICYLATE
AND ISOCYANIDE LIGANDS AS POTENTIAL PRECURSORS OF RADIOPHARMACEUTICALS//
Applied Radiation and Isotopes. 2011. Т. 69. № 2. С. 436-442
13. Melquiades F.L., Parreira P.S., Appoloni C.R., Silva W.D., Lopes F.
QUANTIFICATION OF METALS IN RIVER WATER USING A PORTABLE EDXRFSYSTEM//
Applied Radiation and Isotopes. 2011. Т. 69. № 2. С. 327-333.
14. Baccouche S., Trabelsi A., Al-Azmi D., Karunakara N.
APPLICATION OF THE MONTE CARLO METHOD FOR THE EFFICIENCY CALIBRATION OF CSI AND NAI DETECTORS FOR GAMMA-
RAY MEASUREMENTS FROM TERRESTRIAL SAMPLES//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 227-232
15. Konki J., Greenlees P.T., Jakobsson U., Jones P., Julin R., Juutinen S., Ketelhut S., Hauschild K., Lopez-Martens A., Nieminen P., Nyman M.,
Peura P., Rahkila P., Ruotsalainen P., Sarén J., Scholey C., Sorri J., Uusitalo J., Kontro R., Mattila A. et al.COMPARISON OF GAMMA-RAY
COINCIDENCE AND LOW-BACKGROUND GAMMA-RAY SINGLES SPECTROMETRY//
Applied Radiation and Isotopes. 2012. Т. 70. № 2. С. 392-396.
16. Nilchi A., Saberi R., Rasouli Garmarodi S., Bagheri A.
EVALUATION OF PAN-BASED MANGANESE DIOXIDE COMPOSITE FOR THE SORPTIVE REMOVAL OF CESIUM-137 FROM AQUEOUS
SOLUTIONS//
Applied Radiation and Isotopes. 2012. Т. 70. № 2. С. 369-374.
17. Crespo M.T.
A REVIEW OF ELECTRODEPOSITION METHODS FOR THE PREPARATION OF ALPHA-RADIATION SOURCES//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 210-215
18. Patil B.J., Bhoraskar V.N., Dhole S.D., Chavan S.T., Pethe S.N., Krishnan R.
DESIGN OF 6MEV LINEAR ACCELERATOR BASED PULSED THERMAL NEUTRON SOURCE: FLUKA SIMULATION AND EXPERIMENT//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 149-155.
19. Borhani zarandi M., Amrollahi Bioki H., Mirbagheri Z.-A., Mirjalili G., Tabbakh F.
EFFECT OF CRYSTALLINITY AND IRRADIATION ON THERMAL PROPERTIES AND SPECIFIC HEAT CAPACITY OF LDPE &
LDPE/EVA//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 1-5.
20. Alharbi A.A., Azzam A.
THEORETICAL CALCULATIONS OF THE REACTION CROSS-SECTIONS FOR PROTON-INDUCED REACTIONS ON NATURAL COPPER
USING ALICE-IPPE CODE//
Applied Radiation and Isotopes. 2012. Т. 70. № 1. С. 88-98
21. Jörg G., Lierse v. Gostomski C., Amelin Y., Kossert K.PRECISE AND DIRECT DETERMINATION OF THE HALF-LIFE OF41CA//
Geochimica et Cosmochimica Acta. 2012. Т. 88. С. 51-65.
22. Biegalski S.R., Saller T., Helfand J., Biegalski K.M.F.
SENSITIVITY STUDY ON MODELING RADIOXENON SIGNALS FROM RADIOPHARMACEUTICAL PRODUCTION FACILITIES//
Journal of Radioanalytical and Nuclear Chemistry. 2010. Т. 284. № 3. С. 663-668.
23. Rivals I., Fabbri C., Euvrard G., Blanchard X.
A BAYESIAN METHOD WITH EMPIRICALLY FITTED PRIORS FOR THE EVALUATION OF ENVIRONMENTAL RADIOACTIVITY:
APPLICATION TO LOW-LEVEL RADIOXENON MEASUREMENTS
Journal of Radioanalytical and Nuclear Chemistry. 2012. Т. 292. № 1. С. 141-153
24. Wan Mahmood Z.U., Yii M.-W.
MARINE RADIOACTIVITY CONCENTRATION IN THE EXCLUSIVE ECONOMIC ZONE OF PENINSULAR MALAYSIA: 226RA,228RA
AND228RA/226RA//
Journal of Radioanalytical and Nuclear Chemistry. 2012. Т. 292. № 1. С. 183-192.
25. Gledenov Yu.M., Sedysheva M.V., Zhang G., Liu J., Wu H., Liu X., Chen J., Khuukhenkhuu G., Szalanski P.J., Koehler P.E.
CROSS-SECTION MEASUREMENT AND ANALYSIS FOR THE SM149(N,α)ND146 REACTION AT 6.0 MEV//
Physical Review C - Nuclear Physics. 2010. Т. 82. № 1. С. 014601.
26. Stochioiu A., Bercea S., Sahagia M., Ivan C., Tudor I., Celarel A.THE MEASUREMENT OF THE NATURAL RADIATION BACKGROUND IN A
SALT MINE//Romanian Journal in Physics. 2011. Т. 56. № 5-6. С. 757-761
27. Семинский К.Ж., Бобров А.А.
СРАВНИТЕЛЬНАЯ ОЦЕНКА РАДОНОВОЙ АКТИВНОСТИ РАЗНОТИПНЫХ И РАЗНОРАНГОВЫХ РАЗЛОМОВ БАЙКАЛЬСКОГО
РИФТА И ЮГА СИБИРСКОЙ ПЛАТФОРМЫ//
Доклады Академии наук. 2009. Т. 427. № 4. С. 521-525.
28. Семинский К.Ж., Дэмбэрэл C., Тугарина М.А., Ганзориг Д., Борняков С.А.
ПЕРВЫЕ ОЦЕНКИ ОБЪЕМНОЙ АКТИВНОСТИ ПОЧВЕННОГО РАДОНА В РАЗЛОМНЫХ ЗОНАХ ЦЕНТРАЛЬНОЙ МОНГОЛИИ //
Доклады Академии наук. 2012. Т. 447. № 2. С. 199
29. Богушевич С.Е., Лысенко Г.Н.
СПЕКТРОСКОПИЧЕСКОЕ ИССЛЕДОВАНИЕ ТЕРМОЛИЗА СУЛЬФИТА КАЛЬЦИЯ//
Журнал неорганической химии. 2009. Т. 54. № 4. С. 674-679.
Методами ТГА, ЭПР и ИК-спектроскопии исследовано термическое превращение сульфита кальция
в сульфат в воздушной атмосфере. Показано участие кристаллизационной воды CaSO3 · 0.5Н2 в
образовании термоиндуцированных ион-радикалов SO . Предложен механизм реакции термолиза.
30. Степаненко В.Ф., Скворцов В.Г., Иванников А.И., Дубов Д.В., Цыб А.Ф.
МЕТОДЫ ИНДИВИДУАЛЬНОЙ РЕТРОСПЕКТИВНОЙ ФИЗИЧЕСКОЙ ДОЗИМЕТРИИ В ПРОБЛЕМЕ ОЦЕНКИ ПОСЛЕДСТВИЙ
НЕКОНТРОЛИРУЕМЫХ РАДИАЦИОННЫХ ВОЗДЕЙСТВИЙ//
Радиационная биология. Радиоэкология. 2011. Т. 51. № 1. С. 168-177.
Представлен обзор результатов разработки, верификации и применения методов индивидуальной
физической ретроспективной дозиметрии населения загрязненных радионуклидами населенных
пунктов, подвергшихся радиационному воздействию в результате аварии на ЧАЭС, а также на
территориях в ареале Семипалатинского ядерного полигона. Даны оценки чувствительности методов
физической ретроспективной дозиметрии. Приведены данные об индивидуальных дозах облучения
населения, подвергшегося неконтролируемому радиационному воздействию.
31. Богданович Б.Ю., Крутиков М.Г., Нестерович А.В., Никулин Б.А., Шиканов А.Е.
ИСПОЛЬЗОВАНИЕ НЕЙТРОННЫХ ПОЛЕЙ ЛИНЕЙНЫХ УСКОРИТЕЛЕЙ НУКЛИДОВ ВОДОРОДА ДЛЯ ИССЛЕДОВАНИЯ ОБРАЗЦОВ
ГОРНЫХ ПОРОД//
Ядерная физика и инжиниринг. 2010. Т. 1. № 6. С. 526-533.
В статье проведен анализ возможности использования линейных ускорителей нуклидов водорода в
качестве нейтронных генераторов для элементного анализа горных пород. Основное внимание
уделено вопросам элементного анализа на золото, уран и породообразующие элементы,
составляющие коллекторы продуктивных углеводородов. Обсуждаются возможные варианты
реализации рассматриваемых методик.
32. Zhou, Jiaxi; Huang, Zhilong; Zhou, Meifu; et al.
Constraints of C-O-S-Pb isotope compositions and Rb-Sr isotopic age on the origin of the Tianqiao
carbonate-hosted Pb-Zn deposit, SW China //ORE GEOLOGY REVIEWS Volume: 53 Pages: 77-92 SEP 2013
The Tianqiao Pb-Zn deposit in the western Yangtze Block, southwest China, is part of the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn
metallogenic province. Ore bodies are hosted in Devonian and Carboniferous carbonate rocks, structurally controlled by a thrust
fault and anticline, and carried about 0.38 million tons Pb and Zn metals grading >15% Pb + Zn. Both massive and disseminated
Pb-Zn ores occur either as veinlets or disseminations in dolomitic rocks. They are composed of ore minerals, pyrite, sphalerite and
galena, and gangue minerals, calcite and dolomite. delta S-34 values of sulfide minerals range from +8.4 to +14.4 parts per
thousand and display a decreasing trend from pyrite, sphalerite to galena (delta S-34(pyrite)>delta S-34(sphalerite)>delta S34(galena)). We interpret that reduced sulfur derived from sedimentary sulfate (gypsum and barite) of the host Devonian to
Carboniferous carbonate rocks by thermal-chemical sulfate reduction (TSR). delta C-13(PDB) and delta O-18(SMOW) values of
hydrothermal calcite range from -5.3 to -3.4 parts per thousand. and +14.9 to +19.6 parts per thousand, respectively, and fall in the
field between mantle and marine carbonate rocks. They display a negative correlation, suggesting that CO2 in the hydrothermal
fluid was a mixture origin of mantle, marine carbonate rocks and sedimentary organic matter. Sulfide minerals have homogeneous
and low radiogenic Pb isotope compositions (Pb-206/Pb-204 = 18.378 to 18.601, Pb-207/Pb-204 = 15.519 to 15.811 and Pb208/Pb-204 = 38.666 to 39.571) that are plotted in the upper crust Pb evolution curve and overlap with that of Devonian to
Carboniferous carbonate rocks and Proterozoic basement rocks in the SYG province. Pb isotope compositions suggest derivation
of Pb metal from mixed sources. Sulfide minerals have Sr-87/Sr-86 ratios ranging from 0.7125 to 0.7167, higher than Sinian to
Permian sedimentary rocks and Permian Emeishan flood basalts, but lower than basement rocks. Again, Sr isotope compositions
are supportive of a mixture origin of Sr. They have an Rb-Sr isotopic age of 191.9 +/- 6.9Ma, possibly reflecting the timing of Pb-Zn
mineralization. C-O-S-Pb-Sr isotope compositions of the Tianqiao Pb-Zn deposit indicate a mixed origin of ore-forming fluids, which
have Pb-Sr isotope homogenized before the mineralization. The Permian flood basalts acted as an impermeable layer for the PbZn mineralization hosted in the Devonian-Carboniferous carbonate rocks. (C) 2013 Elsevier B.V. All rights reserved.
33. Jemmali, Nejib; Souissi, Fouad; Carranza, Emmanuel John M.; et al.
Sulfur and lead isotopes of Guern Halfaya and Bou Grine deposits (Domes zone, northern Tunisia):
Implications for sources of metals and timing of mineralization //
ORE GEOLOGY REVIEWS Volume: 54 Pages: 17-28
OCT 2013
The Pb-Zn ore deposits in the Guern Halfaya and Bou Grine areas (northern Tunisia) are hosted mainly by dolostones in the
contact zone between Triassic and Upper Cretaceous strata and by Upper Cretaceous limestones. The deposits occur as
lenticular, stratiform, vein, disseminations and stockwork ore bodies consisting of sphalerite, galena, pyrite, chalcopyrite and
sulfosalt (gray copper). Barite and celestite dominate the gangue, with lesser calcite. The delta S-34 values of barite and celestite
(12.7-15.0 parts per thousand) at the Oum Edeboua mine are consistent with the reduction of sulfates in Triassic evaporites within
the study area (12.8 < delta S-34 < 14.0 parts per thousand). The delta S-34 values in base-metal sulfides from both study areas
(2.6-9.5 parts per thousand) and the presence of bacterial relics suggest involvement of bacterially-mediated sulfate reduction in
the mineralization. The present Pb isotope data are homogeneous with Pb-206/Pb-204, Pb-207/Pb-204 and Pd-208/Pb-204 ratios
of 18.723-18.783, 15.667-15.685 and 38.806-38.889, respectively, which suggest a single source reservoir of Pb at depth in the
upper crust. The syn-diagenetic mineralization in the Bahloul Formation and the calculated age from the Pb isotopic data suggest
an Upper Cretaceous age for the Pb-Zn deposits in the Guern Halfaya and Bou Grine areas. During this period, NE-SW to ENEWSW trending regional extensional tectonic structures likely favored migration of mineralizing fluids and eventual deposition at
Guern Halfaya and Bou Grine.
34. Zhang, Jing; Chen, Yan-Jing; Pirajno, Franco; et al. Geology, C-H-O-S-Pb isotope systematics and geochronology
of the Yindongpo gold deposit, Tongbai Mountains, central China: Implication for ore genesis //
ORE GEOLOGY REVIEWS Volume: 53 Pages: 343-356 DOISEP 2013
The Yindongpo gold deposit is located in the Weishancheng Au-Ag-dominated polymetallic ore belt in Tongbai Mountains, central
China. The ore bodies are stratabound within carbonaceous quartz-sericite schists of the Neoproterozoic Waitoushan Group. The
ore-forming process can be divided into three stages, represented by early barren quartz veins, middle polymetallic sulfide veinlets
and late quartz-carbonate stockworks, with most ore minerals, such as pyrite, galena, native gold and electrum being formed in the
middle stage. The average delta O-18(water) values changed from 9.7 parts per thousand in the early stage, through 4.9 parts per
thousand in the middle stage, to -5.9 parts per thousand in the late stage, with the delta D values ranging between -65 parts per
thousand and -84 parts per thousand. The delta C-13(CO2) values of ore fluids are between -3.7 parts per thousand and +6.7 parts
per thousand, with an average of 1.1 parts per thousand. The H-O-C isotope systematics indicate that the ore fluids forming the
Yindongpo gold deposit were probably initially sourced from a process of metamorphic devolatilization, and with time gradually
mixed with meteoric water. The delta S-34 values range from -0.3% to +5.2 parts per thousand, with peaks ranging from +1 parts
per thousand to +4 parts per thousand. Fourteen sulfide samples yield Pb-206/Pb-204 values of 16.990-17.216, Pb-207/Pb-204 of
15.419-15.612 and Pb-208/Pb-204 of 38.251-38.861. Both S and Pb isotope ratios are similar to those of the main lithologies of the
Waitoushan Group, but differ from other lithologic units and granitic batholiths in the Tongbai area, which suggest that the ore
metals and fluids originated from the Waitoushan Group. The available K-Ar and Ar-40/Ar-39 ages indicate that the ore-forming
process mainly took place in the period of 176-140 Ma, during the transition from collisional compression to extension and after the
closure of the oceanic seaway in the Qinling Orogen. The Yindongpo gold deposit is interpreted as a stratabound orogenic-style
gold system formed during the transition phase from collisional compression to extension.
The ore metals in the Waitoushan Group were extracted, transported and then accumulated in the carbonaceous sericite schist
layer. The carbonaceous sericite schist layer, especially at the junction of collapsed anticline axis and fault structures, became the
most favorable locus for the ore bodies.
35. Dong, Guochen; Santosh, M.; Li, Shengrong; et al.
Mesozoic magmatism and metallogenesis associated with the destruction of the North China Craton:
Evidence from U-Pb geochronology and stable isotope geochemistry of the Mujicun porphyry Cu-Mo deposit
//ORE GEOLOGY REVIEWS Volume: 53 Pages: 434-445 DOI: 10.1016/j.oregeorev.2013.02.006 Published: SEP 2013
The North China Craton (NCC) provides a classic example of lithospheric destruction and refertilization. The timing and duration of
magmatism and related metallogenesis associated with the destruction process are pivotal to understanding the geodynamic
controls. In this study, we present zircon U-Pb and Hf data, Re-Os ages, and He, Ar, Pb and S isotope data from the Mujicun
porphyry Cu-Mo deposit in the northern Taihang Mountains within the Central Orogenic Belt of the NCC. We constrain the timing of
magmatism as 144.1 +/- 1.2 Ma from zircon U-Pb data on the diorite porphyry that hosts Cu-Mo mineralization. Another U-Pb age
of 139.7 +/- 1.4 Ma was obtained from an epidote skarn that is located in the contact zone between the porphyry and its wall rocks.
These data and five Re-Os molybdenite ages that range from 142.7 +/- 2.0 Ma to 138.5 +/- 1.9 Ma suggest that magmatism and
mineralization occurred in about five million year duration from similar to 143 Ma to similar to 138 Ma. The He, Ar, Pb and, Hf data
suggest that magmatism involved recycled Neoarchean lower crustal components, with input of heat and volatiles from an
upwelling mantle. The Mujicun porphyry and associated mineralization provide a typical example for magmatism and metallogeny
associated with lithospheric thinning in the NCC.
36. Kaljo, Dimitri; Martma, Tonu; Grytsenko, Volodymyr; et al.
Pridoli carbon isotope trend and upper Silurian to lowermost Devonian chemostratigraphy based on sections
in Podolia (Ukraine) and the East Baltic area //ESTONIAN JOURNAL OF EARTH SCIENCES Volume: 61 Issue: 3
Pages: 162-180
SEP 2012
Insufficient knowledge of carbon isotope cycling in the latest Silurian initiated the study of two regions at the western and
southwestern margins of Baltica in order to obtain a more complete picture about the carbon isotope trend through the Pridoli.
Shallow and open shelf carbonate rocks of the Dniester River outcrops and Kotuzhiny core in Podolia and deep shelf rocks of the
East Baltic area, especially the Lithuanian cores, were studied for bulk-rock isotope analysis. The data sets of both regions begin
with the mid-Ludfordian excursion and include also some part of the lowermost Devonian. The data show a new minor twin positive
delta C-13 excursion (peak values 0.8-1.7 parts per thousand) in the upper Ludfordian. The Pridoli carbon isotope trend begins with
a low of negative delta C-13 values, succeeded by the lower to middle Pridoli 'stability' interval (variable values below or close to 0
parts per thousand with a slight rising trend). The upper Pridoli begins with a medium to major excursion (peak values 2.3-4.5 parts
per thousand), which reflects the pattern of the carbon isotope trend on the west of the Baltica palaeocontinent. Its wider
significance awaits confirmation from observations elsewhere. The carbon isotope excursion at the Silurian Devonian boundary,
named here the SIDE excursion (its delta C-13 values range from 1.6 parts per thousand in deep shelf settings to 3.8 parts per
thousand in shallower ones and 4.5 parts per thousand in brachiopod shells), has been traced on several continents, and now also
in Baltica. This excursion can serve as a well-dated global chemostratigraphic correlation tool. The shape of the excursion indicates
the completeness of the studied section. We conclude that carbon isotope chemostratigraphy may contribute to subdividing the
Pridoli Series into stages and that Baltica sensu lato seems to be the right place for such a development.
37. Kaljo, Dimitri; Maennik, Peep; Martma, Tonu; et al.
More about the Ordovician-Silurian transition beds at Mirny Creek, Omulev Mountains, NE Russia: carbon
isotopes and conodonts //ESTONIAN JOURNAL OF EARTH SCIENCES Volume: 61 Issue: 4 Special Issue: SI Pages:
277-294 DEC 2012
Profound environmental and biodiversity changes take place in the Ordovician-Silurian boundary interval. The Mirny Creek and
Neznakomka River bank sections discussed in this paper expose the upper Katian-lower Rhuddanian part of the boundary beds.
The succession consists of carbonate rocks, partly with bioherms, alternating with argillaceous and siltstone packages that are well
dated by graptolites. Microfossils are rare, especially in the Hirnantian, but conodonts provide some useful markers just below and
above the Hirnantian stage boundaries. The Hirnantian delta C-13 trend in the Mirny Creek section is the stratigraphically longest
described so far and it has a highly specific shape. The trend commenced at the first appearance datum of Normalograptus
extraordinarius or slightly below this level. The main peak occurs near the middle of the N. persculptus Biozone. Samples from the
Neznakomka River suggest a somewhat wider peak interval than at Mirny Creek. Detailed comparison of the Mirny and Stirnas
(Latvia) delta C-13 curves shows a general similarity despite great specific features of both trends. Correlation of the delta C-13
trends from China, Baltica and North America with that at Mirny Creek reveals a great variety of shapes of the carbon isotope
curve. However, its rising limb commenced, if represented, everywhere close to the beginning of the N. extraordinarius Biozone or
in terms of the Baltic succession, at the bottom of the Porkuni Regional Stage. Most likely a general shape of the HICE trend is
pyramidal, which is peaking in the early N. persculptus Biochrone. Differences in the values and shape of an actual curve at
different localities depend on local environmental conditions, sometimes modifying the global signal rather strongly.
38. Bejaoui, J.; Bouhlel, S.; Barca, D.; et al.The Vein-type Zn-(Pb, Cu, As, Hg) mineralization at Fedj Hassene orefield,
North-Western Tunisia: Mineralogy, Trace Elements, Sulfur Isotopes and Fluid Inclusions //ESTUDIOS
GEOLOGICOS-MADRID Volume: 67 Issue: 1 Pages: 5-20
2011
The Fedj Hassene district is localized at the edge of the Tuniso-Algerian border 10 km of Ghardimaou area. It consists of a Zn-Pb
vein type with minor amounts of Cu-As-Hg. The total Zn reserves are about 370.000t. The mineralization occurs within subparallel
fractures to the Ain El Kohla ESE-WNW fault. Host rocks consist of limestones and marly limestones of the Middle Turonian. In the
principal lode of Fedj Hassene, the mineralization occurs as vein filling of massive and brecciated brown sphalerite and minor
galena ore with gangue. Other trace minerals are pyrite, chalcopyrite, orpiment, realgar, smithsonite and cerussite. LA-ICP-MS
analyses in sphalerites show mean contents of 0,84 wt% Fe, 0,14 wt% Cd and 0,02 wt% Mn Ore.
Fluid inclusions study in calcite and sphalerite reveals one mineralizing fluid characterized by an average salinity 23% wt NaCl with
decreasing homogenisation temperature. In fact the temperature shows decrease from sphalerite to calcite. The fluid density that
corresponds to trapping pressure ranges between 1.00 g/cm(3) and 1.11 g/cm(3) and pressure close to 200 bars.
Microthermometric data in fluid inclusion hosted by gangue mineral presented by calcite show an average temperature of formation
around 194 degrees C. These inclusions homogenized to the liquid phase between 156 degrees C and 210 degrees C and
salinities values ranging from 22 to 28 wt% NaCl and an average around 23% wt NaCl.
The delta(34)S (VCDT) values of sphalerite are in the range of + 4,6 parts per thousand to 6,4 parts per thousand (average=5,6
parts per thousand). Thermo-chemical reduction of Triassic sulfate by reaction with hydro-carbons is the most probable source for
the heavy and the narrow range of the delta(34)S values.
Mineralogical, geochemical of trace elements, fluid inclusions and sulfur isotopes studies allow to include the vein-type ore field of
Fedj Hassene in the polymetallic (Pb-Zn-As-Hg) vein mineralization of the nappe zone in northern Tunisia and north eastern
Algeria.
39. Prado, J. L.; Alberdi, M. T.; Sanchez, B.; et al.
The extinction of Equidae and Proboscidea in South America. A test using Carbon isotope data //ESTUDIOS
GEOLOGICOS-MADRID Volume: 67 Issue: 2 Pages: 363-373
2011
Carbon isotopes, preserved in 166 samples of fossil teeth and bone, provide key data for understanding the ecology of extinct
horses and gomphotheres during the Plio-Pleistocene in South America. To analyze the patterns of dietary partitioning throughout
this time we divided the samples into 19 groups, taking into account the genus and the age of the corresponding localities. In this
study, the diets of both groups are assessed to test extinction hypotheses. The strong resource partitioning among herbivores
assumed under Co-evolutionary disequilibrium hypothesis is supported by isotopic data of horses from latest Pleistocene. Hippidon
and Equus had very different diets. In contrast, species of gomphotheres from late Pleistocene in South America seem to have had
less specialized diets containing a broad mix of both C-3 and C-4 plants, which is in line with the dietary assumptions of the
mosaic-nutrient hypothesis, but does not support the assumptions of Co-evolutionary disequilibrium hypothesis.
40. Sanchez, V.; Martin-Crespo, T.; Vindel, E.; et al.
He isotopes constraints to the origin of hydrothermal fluids: application to the fluorite mineralizations of
Asturias (N Spain) //ESTUDIOS GEOLOGICOS-MADRID Volume: 66 Issue: 1 Pages: 75-82 2010
Helium isotopes have been measured in fluorite and sulphides in order to obtain conclusive means of assessing the involvement of
mantle and crustally derived volatiles in F-Ba deposits from Asturias (N of Spain). Fluorite mineralizations are hosted in Mesozoic
(Permotriassic) and Paleozoic age rocks. Mineralization is composed of fluorite, barite, calcite, dolomite, quartz and sulphides, and
shares the characteristics of most Mississippi Valley Type (MVT) deposits associated with rifting events related to the opening of
the Atlantic Ocean. The (3)He/(4)He values of the Asturias ore fluids (<= 0,1 Ra) indicate a crustal fluid source and exclude the
involvement of a mantle helium component. These values are consistent with the acceptance of the existing basinal model for MVT
genesis and sedimentary brines migration, with the lack of igneous activity in the area contemporary with the mineralization, and
also consistent with similar helium isotope data recorded in other fluorite deposits in Europe.
41. Rogov, Mikhail A.; Price, Gregory D.
New stratigraphic and isotope data on the Kimmeridgian-Volgian boundary beds of the Subpolar Urals,
Western Siberia //GEOLOGICAL QUARTERLY Volume: 54 Issue: 1 Pages: 33-40 Published: 2010
A review and new data regarding the ammonite faunas and biostratigraphy of the uppermost Kimmeridgian-lowermost Volgian of
the Subpolar Urals are presented. The combined ranges of almost all ammonite genera in the lowermost Volgian of the Subpolar
Urals supports the traditional point of view regarding the equivalence of the Magnum Zone with the two lowermost Bolonian Zones
and with the bulk of the Klimovi Zone. This stratigraphic interpretation permits the stable isotope data (carbon and oxygen) derived
from associated belemnites to be presented in context. The isotopic records from the belemnites suggest that the lower Volgian
sediments of the Yatria River, Subpolar Ural Mountains were deposited in a warm marine environment consistent with a warm high
latitude scenario. If reduced salinites arc invoked apparent temperatures are lowered by similar to 5 degrees C, but still remain well
above freezing and are relatively warm compared to some recent modelled estimates of Late Jurassic ocean temperatures.
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42. Price, Gregory D.; Passey, Benjamin H.
Dynamic polar climates in a greenhouse world: Evidence from clumped isotope thermometry of Early
Cretaceous belemnites //GEOLOGY Volume: 41 Issue: 8 Pages: 923-926 AUG 2013
Sub-arctic Cretaceous (Berriasian-late Valanginian, ca. 145-134 Ma) marine temperatures obtained from fossil mollusks
(belemnites) are determined using carbonate clumped isotope thermometry, an approach based on the "clumping" of C-13 and O18 in the carbonate mineral lattice into bonds with each other. From our analyses we infer sub-arctic Early Cretaceous marine
temperatures ranging from 10 degrees C to 20 degrees C. These possibly seasonally biased, warm sub-arctic temperatures are
warmer than present mean summer water temperatures at 60-65 degrees N and are therefore consistent with a warmer
"greenhouse" world featuring a shallow (equable) latitudinal temperature gradient. Our combined temperature and delta O18(belemnite) data imply seawater delta O-18 values that have a remarkably modern character in that they are similar to modern
high-latitude seawater but more positive than modeled Cretaceous seawater. We identify a cooler late Valanginian interval (ca. 134
Ma) with temperatures consistent with polar regions a few degrees above freezing and also coincident with increased delta O-18
seawater values. Thus we find evidence of intervals when polar ice was unlikely, and also when polar ice was plausible. Both
scenarios support the view of generally warm but dynamic polar climates during greenhouse intervals that were punctuated by
periods of ice growth.
43. : Xue, Yunxing; Campbell, Ian; Ireland, Trevor R.
No mass-independent sulfur isotope fractionation in auriferous fluids supports a magmatic origin for Archean
gold deposits //GEOLOGY Volume: 41 Issue: 7 Pages: 791-794 JUL 2013
The source of the auriferous fluids that formed Archean greenstone gold deposits remains controversial; metamorphic fluids, fluids
derived from felsic magmas, mantle fluids, and meteoric water have all been suggested. We report the results of ion microprobe
(sensitive high-resolution ion microprobe stable isotopes) multiple sulfur isotope analyses (S-32, S-33, (3)4S) conducted to
constrain the source of sulfur in four Archean gold deposits. The analyses are of pyrite samples that are genetically related to the
gold mineralization from the Bellerophon, Victory, and Wallaby deposits in the Eastern Goldfield superterrane of the Yilgarn craton,
Western Australia, together with sulfide from black shale from the Golden Mile deposit and St. Ives gold camp. Ore-associated
pyrite from the Beattie gold deposit of the Abitibi greenstone belt of the Superior craton in Canada was measured to test whether
the results obtained from the Yilgarn craton apply to other Archean gold deposits. Sulfur analyses from sulfide from shale show
mass-independent fractionation (MIF) with Delta S-33 as high as +1.8 parts per thousand, whereas those from the 4 Archean gold
deposits are dominated by mass-dependent fractionation, with only a minor contribution of MIF sulfur. In this respect, Archean gold
deposits contrast with Archean NiS deposits, which are dominated by MIF sulfur. The absence of MIF in the pyrite from the four
Archean gold deposits analyzed in this study is consistent with the auriferous fluid originating from a felsic magma or mantle
source, but inconsistent with the metamorphic and meteoritic fluid hypotheses.
44. Gomes, Maya L.; Hurtgen, Matthew T.
Sulfur isotope systematics of a euxinic, low-sulfate lake: Evaluating the importance of the reservoir effect in
modern and ancient oceans //GEOLOGY Volume: 41 Issue: 6 Pages: 663-666 JUN 2013
The sulfur (S) isotope difference between sedimentary sulfate and sulfide phases preserved in sedimentary rocks (Delta S-34) has
been utilized to reconstruct marine sulfate concentrations and inferentially the redox evolution of Earth's surface. These
interpretations are largely based on experimental studies that indicate that microbial sulfate reduction is accompanied by a
substantial kinetic isotope effect (up to 66 parts per thousand), but only at sulfate concentrations >similar to 200 mu M. In this
study, we examine S isotope systematics in a modern, low-sulfate euxinic lake (similar to 100-350 mu M) and find that the
calculated kinetic isotope effect associated with microbial sulfate reduction (epsilon S-34) is relatively large (similar to 23.5 parts per
thousand), but preserved Delta S-34 values are considerably smaller (4.7 parts per thousand-9.9 parts per thousand). Delta S-34
values in this system are controlled by the fraction of the sulfate reservoir that is consumed during sulfate reduction and the location
of pyrite formation. This reservoir effect strongly influences the S isotope composition of sulfide preserved in the rock record such
that Delta S-34 values increase as a function of sulfate levels, even when sulfate concentrations are > 200 mu M and the kinetic
isotope effect is expressed. These findings have important implications for reconstructing the chemical evolution of the oceanatmosphere system throughout Earth history-not just for the Precambrian.
45. Raitzsch, Markus; Hoenisch, Baerbel
Cenozoic boron isotope variations in benthic foraminifers //GEOLOGY Volume: 41 Issue: 5 Pages: 591-594
MAY
2013
The boron isotopic composition of seawater (delta B-11(sw)) is a prerequisite for reliably estimating past variation of seawater pH
from boron isotopes in marine carbonates (delta B-11(c)). Here we compose a 50 m.y. stack of delta B-11(c) from Atlantic and
Pacific Ocean deep-sea sediments, and discuss the potential effects of deep-sea pH and delta B-11(sw) on our record. Using
model-based Cenozoic pH values, the inferred delta B-11(sw) values suggest an similar to 3 parts per thousand increase since the
Late Eocene, superimposed on oscillating variations with amplitudes of up to 2 parts per thousand. Our estimates match existing
reconstructions of delta B-11(sw), but call into question published fluid delta B-11 in halite as a recorder of delta B-11(sw).
46. Genske, Felix S.; Beier, Christoph; Haase, Karsten M.; et al.
Oxygen isotopes in the Azores islands: Crustal assimilation recorded in olivine //
GEOLOGY Volume: 41 Issue: 4 Pages: 491-494
APR 2013
Oxygen isotope ratios of olivine have become a widely used tool for the study of magmatic systems, especially in the interpretation
of source heterogeneities in mantle plume-derived ocean island basalts. The underlying assumption is that fresh minerals provide a
better guide to magma delta O-18 than bulk rock analyses and that olivine is also likely to be a major phenocryst phase in primitive
magmas. However, distinctions between source compositions and the effects of subsequent magma evolution have not always
been thoroughly scrutinized. For the Azores samples investigated here, we can demonstrate that the delta O-18 variation (+4.84%
to +5.25% Vienna standard mean ocean water) observed in the olivine phenocryst population is closely linked to evolution in the
host magmas during ascent to the surface. We observe a linear, positive correlation between forsterite (Fo) content and delta O-18
in all of the individual island lava suites. This forces us to conclude that the low oxygen isotope ratios result from combined
assimilation and fractional crystallization processes, the assimilant being hydrothermally (temperature > 250 degrees C) altered,
lower oceanic crust. Linear regression of the measured delta O-18 olivine values to Fo(89) suggests a homogeneous mantle
source with delta O-18 = +5.2 parts per thousand +/- 0.1 parts per thousand.
47. Peng, Yongbo; Bao, Huiming; Zhou, Chuanming; et al Oxygen isotope composition of meltwater from a
Neoproterozoic glaciation in South China //GEOLOGY Volume: 41 Issue: 3 Pages: 367-370
MAR 2013
The water cycle is an integral part of Earth surface dynamics, and water's oxygen-isotope composition retains information about the
forcing and response of Earth's local and global climate. Water isotope signals of the recent geological past can be directly
obtained from archives such as ice cores, groundwater, or pore fluid. For the more distant past, mineral proxies have to be used.
Multiple episodes of global glaciation may have occurred in the Neoproterozoic Era, of which the record of oxygen-isotope
composition of glacial meltwater is sparse; the few records that are derived from carbonate minerals are prone to late-burial and
metamorphic alteration, and therefore subject to alternative explanations. Here we present a case in which meltwater delta O-18 is
retrieved from barite (BaSO4) and malachite (Cu2CO3(OH)(2))-associated sulfate (MAS) in a diamictite in Kaiyang, Guizhou, South
China. The core of our argument is based on the lowest-ever-published sulfate delta O-18 values found in the barite and MAS,
reaching as low as -20.3 parts per thousand (Vienna standard mean ocean water, VSMOW). These data suggest that the water
involved in the oxidative weathering of these chalcocite clasts had a delta O-18 value of -34 parts per thousand +/- 10 parts per
thousand, similar to that of polar glaciers today. Excluding the possibility of glacier meltwater alteration during the past 600 m.y.
after the deposition of the diamictite, the sulfate mineral assemblage reported here provides an important constraint on the nature
of the Neoproterozoic glaciation that the Kaiyang diamictite represents.
48. Desaulty, Anne-Marie; Albarede, Francis
Copper, lead, and silver isotopes solve a major economic conundrum of Tudor and early Stuart Europe
//GEOLOGY Volume: 41 Issue: 2 Pages: 135-138 FEB 2013
The unrelenting economic inflation of A.D. 1515-1650 in Europe has been variously explained by the influx of silver from Mexico
and the Viceroyalty of Peru (now Bolivia), the growth of the European population, and the decline of the silver market price. Silver,
copper, and lead isotope analyses of A.D. 1550-1650 English coinage show a dominance of silver from Europe and Mexico,
contrasting with a spectacularly small contribution from the Viceroyalty of Peru. This observation contrasts with the registration of
metal production in the mines of the Spanish Americas. Hence the question: Where did Potosi silver go? This novel observation
indicates that silver from Mexico was exported eastward, whereas Potosi silver flowed westward. However, aware of the Pacific
route of the silver trade, scholars never agreed upon the volumes transported. Our work demonstrates that there was a PotosiChina route, and that it was largely disconnected from the Mexico-Europe routes.
49. Lange, Amy E.; Nielsen, Roger L.; Tepley, Frank J., III; et al.
Diverse Sr isotope signatures preserved in mid-oceanic-ridge basalt plagioclase //GEOLOGY Volume: 41 Issue:
2 Pages: 279-282
FEB 2013
At mid-ocean ridges, a variety of crustal processes overprint mantle-derived melts and can obscure original mantle compositions.
To address the nature of this crustal filter, we report Sr-87/Sr-86 ratios from plagioclase phenocrysts and host glasses in midoceanic-ridge basalts from the Juan de Fuca Ridge, Blanco Transform Zone, and the Southwest Indian Ridge. Microdrilled isotopic
analyses reveal significant inter- and intracrystalline disequilibria within individual samples. These disequilibria suggest that a range
of isotopically distinct melt components contribute to individual plagioclase crystals and to the magmas that transport them to the
surface. Low Cl/K values both in the host glass and in plagioclase-hosted melt inclusions largely rule out incorporation of seawaterderived material as an explanation for differences in Sr-87/Sr-86. Instead, the observed heterogeneity implies derivation of magmas
from isotopically diverse mantle sources. Importantly, the range of Sr isotope values preserved in a single sample is similar to the
range of compositions seen at the ridge segment scale. Unlike analyses of host glass compositions, which are the result of
extensive crustal processing, isotopic analyses of phenocryst phases record fine-scale aggregation of these distinct mantle-derived
melts and are thus an important and underutilized tool in interpreting the nature of the mid-oceanic-ridge basalts.
50. Stansell, Nathan D.; Steinman, Byron A.; Abbott, Mark B.; et al.
Lacustrine stable isotope record of precipitation changes in Nicaragua during the Little Ice Age and Medieval
Climate Anomaly //GEOLOGY Volume: 41 Issue: 2 Pages: 151-154 FEB 2013
Discerning the influences of the El Nino Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) on drought variability
in the tropics during the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) will help to improve our understanding of climate
system responses to internal and external forcing. Sediments from Lago El Gancho, Nicaragua, provide an similar to 1400 yr record
of water balance (precipitation and evaporation) changes from a region that is sensitive to teleconnected Pacific and Atlantic
ocean-atmosphere dynamics. Oxygen isotope values of ostracod carapaces (delta O-18(ostracod)) are consistently low in El
Gancho sediments between ca. A.D. 950 and 1250, indicating that wetter conditions prevailed during the MCA, a period of La Ninalike mean state conditions in the tropical Pacific, and a positive mean state of the NAO. The similar to 150 yr period between the
MCA and LIA was marked by an abrupt shift to persistently drier conditions at a time of highly variable Pacific sea-surface
temperatures, and a transition toward a more negative NAO phase. In sediment from ca. A.D. 1450 to the present, delta O18(ostracod) values increase, suggesting that drier conditions persisted through most of the LIA, a time of a relatively negative
NAO phase and El Nino-like mean state conditions in the tropical Pacific. The long-term precipitation trends inferred from the El
Gancho data are not entirely consistent with modern associations between precipitation in the circum-Caribbean region and the
NAO, suggesting that present-day hydroclimatic shifts resulting from variability in synoptic climate patterns are dissimilar to
changes resulting from teleconnected ocean-atmosphere dynamics that operated during the MCA and LIA.
51. Kunzmann, Marcus; Halverson, Galen P.; Sossi, Paolo A.; et al.
Zn isotope evidence for immediate resumption of primary productivity after snowball Earth
//GEOLOGY Volume: 41 Issue: 1 Pages: 27-30 JAN 2013
The Ediacaran period began with the deglaciation of the ca. 635 Ma Marinoan snowball Earth and the deposition of cap dolostones
on continental shelves worldwide during post-glacial sea-level rise. These carbonates sharply overlie glacial sediments deposited at
low pale-olatitudes and preserve negative carbon isotope excursions. The snowball Earth hypothesis invokes an almost complete
cessation of primary productivity in the surface ocean. Because assimilatory uptake of Zn appears to fractionate its isotopes, Zn
isotope ratios measured in carbonate precipitated in the surface ocean should track fluctuations in primary productivity. Here we
report the first Zn isotopic data, together with carbon and oxygen isotopic profiles from a Neoproterozoic cap dolostone, the
Nuccaleena Formation in the Flinders Ranges, South Australia. We interpret the Zn isotopic data in terms of a two-stage evolution
of the deglacial ocean. Slightly Zn-66-enriched values at the base of the cap dolostone indicate immediate resumption of the
biological pump upon melting of the surface ocean, but this signal was diluted by intense surface runoff that drove delta Zn-66 (Zn66/Zn-64, versus the JMC Lyon reference) values down to the composition of continentally derived Zn. A subsequent rise in delta
Zn-66 records a vigorous increase in primary production and export from a nutrient-laden surface ocean.
52. Virtasalo, Joonas J.; Whitehouse, Martin J.; Kotilainen, Aarno T.
Iron isotope heterogeneity in pyrite fillings of Holocene worm burrows //GEOLOGY Volume: 41 Issue: 1 Pages:
39-JAN 2013
We present Fe-54 and Fe-56 data on pyrite from burrow-like and irregularly shaped pyrite concretions from Holocene postglacial
lacustrine clays in the northern Baltic Sea collected using a secondary ion mass spectrometry (SIMS) microanalysis technique. The
burrow-like concretions were formed in reducing, mucus-coated worm burrows in oxic surface sediments. Framboidal pyrite in the
cores of the burrow-like concretions shows extensively fractionated delta Fe-56 values down to -3.1 parts per thousand. The
framboids are cemented by poorly crystalline FeS2 with delta Fe-56 values between -2.1 parts per thousand and +1.4 parts per
thousand. The irregularly shaped concretions with microcrystalline textures were formed in organic-poor sediment pore spaces, and
display a wide spread of delta Fe-56 values up to +4.1 parts per thousand. The measured delta Fe-56 values reflect the preferential
capture of Fe-54 to pyrite in the diagenetic sequence and the Fe-56 enrichment of remaining pore water. The diagenetic sequence
of the pyrite materials is supported by previous petrographical study and S-34/S-32 microanalysis of the same samples. Our results
demonstrate substantial early-diagenetic delta Fe-56 and delta S-34 heterogeneity within individual pyrite grains, underlining the
necessity of high spatial resolution measurements in studying biological and abiological isotopic signatures.
53. McLoughlin, N.; Grosch, E. G.; Kilburn, M. R.; et al.
Sulfur isotope evidence for a Paleoarchean subseafloor biosphere, Barberton, South Africa
//GEOLOGY Volume: 40 Issue: 11 Pages: 1031-1034 DOINOV 2012
The Archean sub-seafloor has been proposed as an environment for the emergence of life, with septate clusters of titanite
microtextures in pillow lava rims argued to be the earliest traces of microbial microboring. Here we use nanoscale secondary ion
mass spectrometry (NanoSIMS) to test possible geochemical traces of life in ca. 3.45 Ga pillow lavas of the Barberton Greenstone
Belt, South Africa. Sulfide inclusions in the titanite microtextures record strongly negative sulfur isotope fractionations of delta S34(VCDT) -39.8 parts per thousand to -3.2 parts per thousand (VCDT-Vienna Canyon Diablo Troilite). These represent the largest
range and most negative delta S-34 values so far reported from the Archean, and are consistent with an early biogenic origin for
the sulfides. Extensive in situ elemental mapping did not find any organic linings associated with the microtextures, despite the high
spatial resolution and sensitivity of the NanoSIMS. The absence of organic linings thus excludes a key line of evidence previously
used to support the biogenicity of the microtextures. In contrast, in situ sulfur isotope analysis of basalt-hosted sulfides provides an
alternative approach to investigating the existence and nature of an Archean subseafloor biosphere.
54. Shen, Jun; Algeo, Thomas J.; Hu, Qing; et al.
Negative C-isotope excursions at the Permian-Triassic boundary linked to volcanism //GEOLOGY Volume: 40
Issue: 11 Pages: 963-966
NOV 2012
Two Permian-Triassic boundary (PTB) sections from south China provide insights regarding the origin of negative excursions in
carbonate and organic carbon isotope records associated with the largest mass extinction in Earth history. Xiakou, a carbonate
ramp section, exhibits delta C-13(carb) excursions of up to -2 parts per thousand, and Xinmin, a deep-shelf section, exhibits delta
C-13(org) excursions of up to -6 parts per thousand. In both sections, these excursions are associated with volcanic ash layers, and
excursion size scales with ash layer thickness. These relationships document the direct influence of volcanism on the Earth-surface
carbon cycle during the PTB crisis. Previous studies of ash layers in south China PTB sections have invoked a source in regional
subduction-zone volcanism in the eastern Tethys, but our analysis suggests that these ash layers may represent distal deposits
from large-scale explosive eruptions of the Siberian Traps. If confirmed by further investigation, this hypothesis would have
important implications both for kill mechanisms during the PTB crisis as well as for refinement of the eruption history of the Siberian
Traps.
55. Scambelluri, Marco; Tonarini, Sonia
Boron isotope evidence for shallow fluid transfer across subduction zones by serpentinized mantle
//GEOLOGY Volume: 40 Issue: 10 Pages: 907-910 OCT 2012
Serpentinites formed by alteration of oceanic and forearc mantle are major volatile and fluid-mobile element reservoirs for arc
magmatism, though direct proof of their dominance in the subduction-zone volatile cycles has been elusive. Boron isotopes are
established markers of fluid-mediated mass transfer during subduction. Altered oceanic crust and sediments have been shown to
release in the subarc mantle B-11-depleted fluids, which cannot explain B-11 enrichment of many arcs. In contrast to these crustal
reservoirs, we document high delta B-11 values retained in subduction-zone Alpine serpentinites. No B-11 fractionation occurs in
these rocks with progressive burial: the released B-11-rich fluids uniquely explain the elevated delta B-11 of arc magmas. B, O-H,
and Sr isotope systems indicate that serpentinization was driven by slab fluids that infiltrated the slab-mantle interface early in the
subduction history.
56. Blaether, Clara L.; Henderson, Gideon M.; Jenkyns, Hugh C. Explaining the Phanerozoic Ca isotope history of
seawater //GEOLOGY Volume: 40 Issue: 9 Pages: 843-846
SEP 2012
A new geochemical budget for the modern marine carbonate sink helps to explain the major features of the Phanerozoic Ca
isotope record. A large compilation of Ca isotope ratios for modern carbonates, incorporating more than 50 new measurements,
represents the quantitatively important components of the system. With this data set, distinct Ca isotope ratios are identified for
different types of marine carbonate, the balance of which has changed over time with shifts between calcite and aragonite seas and
with the development of pelagic calcification during the Mesozoic. It is suggested that large-scale changes in the Ca isotope ratio of
seawater, as exemplified by that in the Carboniferous, were no longer possible after Jurassic time because of the generation of a
deep-sea calcite sink expressed by deposition of foraminiferal-coccolith ooze across the world ocean. This work demonstrates the
close connection between isotopic cycling, carbonate sedimentation, seawater chemistry, and evolutionary trends.
57. Hinojosa, Jessica L.; Brown, Shaun T.; Chen, Jun; et al.
Evidence for end-Permian ocean acidification from calcium isotopes in biogenic apatite //GEOLOGY Volume: 40
Issue: 8 Pages: 743-746 AUG 2012
End-Permian (ca. 252 Ma) carbon isotope, paleobiological, and sedimentary data suggest that changes in ocean carbonate
chemistry were directly linked to the mass extinction of marine organisms. Calcium isotopes provide a geochemical means to
constrain the nature of these changes. The delta Ca-44/40 of carbonate rocks from southern China exhibits a negative excursion
across the end-Permian extinction horizon, consistent with either a negative shift in the delta Ca-44/40 of seawater or a change in
the calcite/aragonite ratio of carbonate sediments at the time of deposition. To test between these possibilities, we measured the
delta Ca-44/40 of hydroxyapatite conodont microfossils from the global stratotype section and point (GSSP) for the PermianTriassic boundary at Meishan, China. The conodont delta Ca-44/40 record shows a negative excursion similar in stratigraphic
position and magnitude to that previously observed in carbonate rocks. Parallel negative excursions in the delta Ca-44/40 of
carbonate rocks and conodont microfossils cannot be accounted for by a change in carbonate mineralogy, but are consistent with a
negative shift in the delta Ca-44/40 of seawater. Such a shift is best accounted for by an episode of ocean acidification, pointing
toward strong similarities between the greatest catastrophe in the history of animal life and anticipated global change during the
twenty-first century.
58. Arnold, G. L.; Lyons, T. W.; Gordon, G. W.; et al.Extreme change in sulfide concentrations in the Black Sea during
the Little Ice Age reconstructed using molybdenum isotopes //GEOLOGY Volume: 40 Issue: 7 Pages: 595-598
JUL 2012
The Black Sea is the largest and most studied anoxic basin in the modern world. Much of this research has focused on the redox
structure of the water column, specifically on the driving forces behind variations in the position, stability, and structure of the oxicanoxic interface (chemocline). However, none of these studies has been able to quantify the historical sulfide concentrations
associated with the changes in chemocline depth. Using the isotopic composition of molybdenum in sediments as a proxy, we show
for the first time that varying concentrations of dissolved sulfide can be fingerprinted in historical systems. Our molybdenum isotope
data indicate that in the region of the Bosporus inlet, the chemocline rose more than 65 m, reaching concentrations over 100 mu M
sulfide in the bottom water ca. 300 yr B.P. This historical shoaling of the chemocline and extreme change in bottom-water sulfide
concentration exceeds the modern changes that have been observed directly and attributed to anthropogenic influences on the
Black Sea chemistry/hydrology. The first cold interval of the Little Ice Age, when temperature and circulation changes occurred in
the Black Sea basins, may have provided the natural trigger for this extreme rise in bottom-water sulfide concentrations.
59. Bottini, Cinzia; Cohen, Anthony S.; Erba, Elisabetta; et al.
Osmium-isotope evidence for volcanism, weathering, and ocean mixing during the early Aptian OAE 1a//
GEOLOGY Volume: 40 Issue: 7 Pages: 583-586
JUL 2012
The early Aptian Oceanic Anoxic Event (OAE 1a) resulted from an exceptional set of interactions between the geosphere, the
biosphere, and the ocean-atmosphere system. We present new Re-Os data from two sites spanning OAE 1a in the Tethys and
Pacific Oceans. The patterns of variation in the seawater Os-isotope composition from both sites are very similar, and together they
constrain the timing and duration of continental weathering in relation to the large-scale volcanic activity of the Ontong Java
Plateau. The dominant feature through the OAE is an interval of similar to 880 k.y. when the Os-isotope composition of the global
ocean was exceptionally unradiogenic, implicating unambiguously the Ontong Java Plateau as the trigger and sustaining
mechanism for OAE 1a. A relatively short-lived (similar to 100 k.y.) Os-isotope excursion to radiogenic compositions in the Tethyan
record is clearly linked to an abrupt perturbation to the global carbon cycle, and is fully consistent with the Pacific record. These
highly distinctive features of seawater Os in contemporaneous samples from three high-resolution sections, two of which were very
remote from the Ontong Java Plateau, indicate that ocean mixing at that time was very efficient. The results suggest that OAE 1a
was also related to rapid global warming and elevated rates of silicate weathering both on the continents and in the oceans.
60. Woodhead, Jon; Stern, Robert J.; Pearce, Julian; et al.
Hf-Nd isotope variation in Mariana Trough basalts: The importance of "ambient mantle" in the interpretation
of subduction zone magmas //GEOLOGY Volume: 40 Issue: 6 Pages: 539-542 JUN 2012
In the study of geochemical mass balances at subduction zones, the composition of the mantle wedge prior to additions from the
slab is a critically important yet poorly constrained parameter. Deconvolving the influence of ancient versus modern enrichments is
particularly difficult, especially when considering elements that are highly mobile. Here we provide an alternative approach, using
less mobile elements, and a filter to remove the effects of recent slab additions. We provide new Hf isotope data for 30 Mariana
Trough (MT) backarc basin lavas. Once filtered, Hf and Nd isotope ratios are highly correlated, of Indian mid-oceanic ridge basalt
character, and display variations similar to ocean ridges of comparable lengths. The isotopic variability observed in this "ambient
mantle" provides a new paradigm for the interpretation of the varied volcanic products of the arc. Thus, shoshonites associated with
the northern termination of the backarc basin rift axis reflect the interaction of a subducted sediment melt with an isotopically
enriched mantle source. In contrast, the large volcanoes of the Central Island province have a consistent offset in Nd isotope
compositions from the MT array resulting from fluid addition. Existing data for smaller edifices in the submarine portion of the arc
have larger variations resulting from fluid addition on a more local scale. We suggest that the similar characterization of ambient
mantle elsewhere may help to resolve many conflicting geochemical observations in arc lavas worldwide.
61. Peucker-Ehrenbrink, Bernhard; Hanghoj, Karen; Atwood, Tracy; et al.Rhenium-osmium isotope systematics and
platinum group element concentrations in oceanic crust //GEOLOGY Volume: 40 Issue: 3 Pages: 199-202
MAR
2012
Knowledge of the Os-187/Os-188 ratio as well as the inventories of rhenium and platinum group elements (PGE) in oceanic crust
allows quantification of the proportion of recycled oceanic crust in oceanic basalt sources. Our knowledge is limited by the
availability of well-characterized sections of oceanic crust, specifically of the plutonic, lower portion that has not been drilled in situ
to the Moho. Here we report new data for plutonic rocks that compose the bottom 4680 m of an ocean crust section from the Oman
ophiolite. Major and trace element data as well as mineral analyses indicate that Oman gabbros are primitive cumulates from melts
similar to typical mid-oceanic ridge basalt. The mean weighted composition of this section (Re: 427 pg/g; Os: 55 pg/g; Ir: 182 pg/g;
Pd: 2846 pg/g; Pt: 4151 pg/g; initial (POs)-P-187/Os-188: 0.142) indicates significantly higher Os and lower Re concentrations than
previously analyzed partial sections of ocean crust that lack cumulate lower crust [Deep Sea Drilling Project Ocean Drilling Program
(DSDP-ODP) Hole 504B, ODP Hole 735B], emphasizing that the lower, cumulate oceanic crust dominates the Os budget of
oceanic crust. Analyses of mineral grain size fractions indicate that rhenium, PGE, and lead are enriched in the sulfur-rich, fine
fraction. This corroborates the notion that small accessory phases, and the melt migration processes affecting them, control these
elements' budgets, distributions, and susceptibilities to alteration. The Re-Os-PGE inventories of a hypothetical 6.5-km-thick
composite section that consists of 1825 m of DSDP Hole 504B like upper oceanic crust and 4680 m of Oman-like lower ocean crust
(Re: 736 pg/g; Os: 45 pg/g; Ir: 133 pg/g; Pd: 2122 pg/g; Pt: 2072 pg/g; initial Os-187/Os-188: 0.146) provide a new comprehensive
assessment of oceanic crust composition. Upon recycling and mixing with reasonable proportions of mantle peridotite, this
composite requires at least 2 G.y. to develop sufficiently radiogenic Os-187/Os-188 to generate high mu (HIMU: mu = U-238/Pb204) basalts.
62. Barker, Philip A.; Hurrell, Elizabeth R.; Leng, Melanie J.; et al.
Seasonality in equatorial climate over the past 25 k.y. revealed by oxygen isotope records from Mount
Kilimanjaro //GEOLOGY Volume: 39 Issue: 12 Pages: 1111-1114 DEC 2011
Multiproxy analysis of a well-dated 25 ka lake sediment sequence from Lake Challa, on the eastern flank of Mount Kilimanjaro
(East Africa), reveals the climatic controls that govern both the lake's paleohydrology and the climate-proxy record contained in the
mountain's receding ice cap. The oxygen isotope record extracted from diatom silica (delta O-18(diatom)) in Lake Challa sediments
captured dry conditions during the last glacial period and a wet late-glacial transition to the Holocene interrupted by Younger Dryas
drought. Further, it faithfully traced gradual weakening of the southeastern monsoon during the Holocene. Overall, delta O18(diatom) matches the branched isoprenoid tetraether (BIT) index of rainfall-induced soil runoff, except during 25-22 ka and the
past 5 k.y. when insolation forcing due to orbital precession enhanced the northeastern monsoon. This pattern arises because
during these two periods, a weakened southeastern monsoon reduced the amount of rainfall during the long rainy season and
enhanced the opposing effect of evaporation intensity and/or length of the austral winter dry season. Importantly, our lake-based
reconstruction of moisture-balance seasonality in equatorial East Africa also helps us understand the oxygen isotope record
contained in Mount Kilimanjaro ice. Negative correlation between ice core delta O-18 and Lake Challa delta O-18(diatom) implies
that moisture balance is not the primary climate control on the long-term trend in ice core delta O-18.
63. Elrick, Maya; Rieboldt, Sarah; Saltzman, Matthew R.; et al.
Oxygen-isotope trends and seawater temperature changes across the Late Cambrian Steptoean positive
carbon-isotope excursion (SPICE event) //GEOLOGY Volume: 39 Issue: 10 Pages: 987-990 OCT 2011
The globally recognized Late Cambrian Steptoean positive C-isotope excursion (SPICE) is characterized by a 3 parts per
thousand-5 parts per thousand positive delta C-13 shift spanning <4 m.y. Existing hypotheses suggest that the SPICE represents a
widespread ocean anoxic event leading to enhanced burial/preservation of organic matter (C-org) and pyrite. We analyzed delta O18 values of apatitic inarticulate brachiopods from three Upper Cambrian successions across Laurentia to evaluate
paleotemperatures during the SPICE. delta O-18 values range from similar to 12.5 parts per thousand to 16.5 parts per thousand.
Estimated seawater temperatures associated with the SPICE are unreasonably warm, suggesting that the brachiopod delta O-18
values were altered during early diagenesis. Despite this, all three localities show similar trends with respect to the SPICE delta C13 curve, suggesting that the brachiopod apatite preserves a record of relative delta O-18 and temperature changes. The trends
include relatively high delta O-18 values at the onset of the SPICE, decreasing and lowest values during the main event, and an
increase in values at the end of the event. The higher delta O-18 values during the global extinction at the onset of the SPICE
suggests seawater cooling and supports earlier hypotheses of upwelling of cool waters onto the shallow shelf. Decreasing and low
delta O-18 values coincident with the rising limb of the SPICE support the hypothesis that seawater warming and associated
reduced thermohaline circulation rates contributed to decreased dissolved O-2 concentrations, which enhanced the
preservation/burial of C-org causing the positive delta C-13 shift.
64. Wolff, John A.; Ellis, Ben S.; Ramos, Frank C Strontium isotopes and magma dynamics: Insights from high-
temperature rhyolites //GEOLOGY Volume: 39 Issue: 10 Pages: 931-934
OCT 2011
Volcanic rocks often exhibit internal heterogeneity in radiogenic isotopes. Isotopic disequilibrium between coexisting phenocrysts
and isotopic zoning within single crystals has been demonstrated in basalts, andesites, dacites, and rhyolites. High-temperature
Snake River-type rhyolites appear to be an exception. Despite the occurrence of Snake River Plain rhyolites in a region of
isotopically highly variable crust and mantle, and significant differences from rhyolite unit to rhyolite unit, little to no Sr isotopic
zoning is found within their feldspar phenocrysts, and feldspars within a single unit define tightly grouped unimodal populations.
High-temperature rhyolitic magmas possess a unique combination of temperature and melt viscosity. Although typically 200
degrees C hotter than common rhyolites, the temperature effect on viscosity is offset by lower water contents (<3.5 wt%), so melt
viscosities are in the same range as common, water-rich, cool rhyolites (10(5)-10(6) Pa s). However, magmatic temperatures are in
the same range as basaltic andesites and andesites; consequently, cation diffusion rates are orders of magnitude greater than
common rhyolites. We hypothesize that this combination of characteristics promotes crystal isotopic homogeneity: viscosities are
too high to permit crystal transfer between liquids of contrasting Sr-87/Sr-86 on time scales shorter than those required for diffusive
homogenization of Sr within phenocrysts (500-10,000 yr). This is not true for most magma types, in which crystal transfer is rapid
(<<100 yr) due to low melt viscosities (basalts and intermediate magmas), or Sr diffusion rates are so slow that equilibration times
are longer than the lifetime of the system (e.g., cool, wet rhyolites: 10(5)-10(6) yr).
65. Wang, Xuan-Ce; Li, Zheng-Xiang; Li, Xian-Hua; et al.
Nonglacial origin for low-delta O-18 Neoproterozoic magmas in the South China Block: Evidence from new insitu oxygen isotope analyses using SIMS //GEOLOGY Volume: 39 Issue: 8 Pages: 735-738 AUG 2011
Low-delta O-18 signatures in supracrustal rocks have been used as geochemical proxies for cold paleoclimates, e.g., glaciations.
Unusual low-delta O-18 values found in Neoproterozoic igneous rocks in parts of the South China Block have thus been genetically
linked to Neoproterozoic glaciation events. However, we report here new oxygen isotope compositions from Neoproterozoic
magmatic zircons in central southern China using in-situ techniques that argue against such an interpretation. Our results show that
(1) low-delta O-18 magmatic zircons started to appear in the South China Block from ca. 870 Ma, coinciding with the tectonic
switching from Sibao orogenesis to postorogenic extension, which occurred more than 150 m.y. prior to the first glaciation event.
The most abundant low-delta O-18 magmatic zircons have ages of 800-700 Ma. (2) The 830-700 Ma magmatic zircons are
characterized by their bimodal nature of oxygen isotope compositions, i.e., mantle-like delta O-18 values (+4.4 parts per thousand
to +5.8 parts per thousand) and high-delta O-18 values (+9.3 parts per thousand to +10.8 parts per thousand). (3) A sharp temporal
change in maximum zircon delta O-18 values in the South China Block coincided with the onset of continental rifting and the
possible arrival of a plume head. (4) No negative delta O-18 zircons have been identified in this study, contrary to previous studies.
These features strongly argue against a glaciation origin for low to negative delta O-18 values in Neoproterozoic magmatic zircons
from southern China. We propose that two stages of high-temperature water-magma interaction during plume-driven magmatism
and continental rifting best explain the low-delta O-18 magmas. The most important implication of this study is that formation of
such low-delta O-18 magmatic zircons was not necessarily related to glacial events and should not be used as a geochemical
proxy for a cold paleoclimate.
66. Griffith, Elizabeth M.; Paytan, Adina; Eisenhauer, Anton; et al Seawater calcium isotope ratios across the Eocene-
Oligocene transition //GEOLOGY Volume: 39 Issue: 7 Pages: 683-686
JUL 2011
During the Eocene-Oligocene transition (EOT, ca. 34 Ma), Earth's climate cooled significantly from a greenhouse to an icehouse
climate, while the calcite (CaCO3) compensation depth (CCD) in the Pacific Ocean increased rapidly. Fluctuations in the CCD
could result from various processes that create an imbalance between calcium (Ca) sources to, and sinks from, the ocean (e. g.,
weathering and CaCO3 deposition), with different effects on the isotopic composition of dissolved Ca in the oceans due to
differences in the Ca isotopic composition of various inputs and outputs. We used Ca isotope ratios (delta Ca-44/40) of coeval
pelagic marine barite and bulk carbonate to evaluate changes in the marine Ca cycle across the EOT. We show that the permanent
deepening of the CCD was not accompanied by a pronounced change in seawater delta Ca-44/40, whereas time intervals in the
Neogene with smaller carbonate depositional changes are characterized by seawater delta Ca-44/40 shifts. This suggests that the
response of seawater delta Ca-44/40 to changes in weathering fluxes and to imbalances in the oceanic alkalinity budget depends
on the chemical composition of seawater. A minor and transient fluctuation in the Ca isotope ratio of bulk carbonate may reflect a
change in isotopic fractionation associated with CaCO3 precipitation from seawater due to a combination of factors, including
changes in temperature and/or in the assemblages of calcifying organisms.
67. Ferry, John M.; Passey, Benjamin H.; Vasconcelos, Crisogono; et al.Formation of dolomite at 40-80 degrees C in the
Latemar carbonate buildup, Dolomites, Italy, from clumped isotope thermometry //GEOLOGY Volume: 39 Issue:
6 Pages: 571-574
JUN 2011
The temperature of formation of replacement dolomite and delta O-18(H2O) of dolomitizing fluid in the Latemar carbonate buildup,
Dolomites, Italy, were estimated independently from carbonate clumped isotope thermometry. Dolomite formed at 42-72 +/- 9-11
degrees C (+/- 2 standard deviations, SD) from fluid with delta O-18(H2O) that averages -0.3% +/- 3.3% (Vienna standard mean
ocean water; +/- 2 SD). The estimated temperature and delta O-18(H2O) are similar to those of modern diffuse flow fluids at midocean ridges, the kind of fluid that has been proposed previously as the dolomitizing fluid in the Latemar buildup, based on the
trace element compositions of dolomite. Calcite in limestone preserves original d18O, but records clumped isotope temperatures,
44-76 +/- 9-11 degrees C (+/- 2 SD), that are higher than those at which the limestone formed. Temperature recorded by calcite,
but not delta O-18, was likely reset during dolomitization. Clumped isotope thermometry has great potential for application to
studies of burial and diagenesis by retrieving independent estimates of temperature and delta O-18(H2O) with uncertainties as low
as +/- 5 degrees C (+/- 2 standard errors, SE) and +/- 0.75% (+/- 2 SE), respectively, from a single stable isotope analysis of a
carbonate mineral.
68. Whittaker, Thomas E.; Hendy, Chris H.; Hellstrom, John C.
Abrupt millennial-scale changes in intensity of Southern Hemisphere westerly winds during marine isotope
stages 2-4 //GEOLOGY Volume: 39 Issue: 5 Pages: 455-458 MAY 2011
The strength of mid-southern latitude westerly atmospheric circulation plays an important role in global climate. Due to a lack of
long, continuous, high-resolution paleoclimate archives from mid-southern latitudes, it remains unclear what factors control changes
in its intensity and how past changes affected the climates of landmasses in their path. Here we show growth rate and stable
isotope (delta O-18, delta C-13) profiles from a South Island, New Zealand, stalagmite (HW3) that permit centennial-scale
investigation of Southern Hemisphere westerly paleointensity between 73 and 11 ka. Correlation between HW3 growth rate and
isotope profiles suggests sensitivity to changes in annual precipitation, a factor controlled by westerly intensity. Low growth rates
and relatively enriched isotope ratios define long-term trends in HW3, supporting existing evidence that weaker westerlies
predominated during the last glacial period. Abrupt millennial-scale events occur frequently, such that the HW3 record resembles
Greenland ice core stable isotope profiles. Furthermore, nearly synchronous timing of nine prominent wet and cool intervals with
Heinrich events supports studies showing that increased westerly intensity is closely linked to North Atlantic cooling. As well as
Heinrich events, the HW3 profiles also show an Antarctic Cold Reversal-like event during deglaciation, advocating for a bipolar
seesaw of global climate at that time.
69. Dhuime, Bruno; Hawkesworth, C. J.; Storey, C. D.; et al.
From sediments to their source rocks: Hf and Nd isotopes in recent river sediments //GEOLOGY Volume: 39
Issue: 4 Pages: 407-410
APR 2011
Unraveling continental evolution from the sedimentary record requires an understanding of time-integrated erosion laws that link
sediments to their source rocks, and the extent to which erosion laws vary in different erosion systems. Detrital zircons from the
Frankland River (southwestern Australia) define a continental growth curve that is strikingly similar to the Nd in shales curve for the
Australian continent. This suggests that the detrital zircon data can be used as a good proxy for the sedimentary record through
time. The advantage is that the age distribution of the zircons allows the contributions from different source regions to be
determined for any sediment sample. Using integrated Hf and U-Pb isotopes in detrital zircons, and Nd isotope ratios of bulk recent
sediments along the Frankland River, the relative contributions of different source terrains have been determined and expressed
through an erosion parameter K, which relates the proportions of the material from different source rocks in the sediments to the
proportions of those source rocks present in the overall catchment of the sediments analyzed. The results suggest that values of K
= 4-6 are representative of mature river systems that sample large source areas, and that these should be used to reevaluate
models of the evolution of the continental crust that were generally limited by the assumption of K. For the Gondwana
supercontinent, K values of 4-6 indicate that at least 50% of the present-day volume of the continental crust was generated by the
end of the Archean.
70. Widerlund, Anders; Andersson, Per S.
Late Holocene freshening of the Baltic Sea derived from high-resolution strontium isotope analyses of
mollusk shells //GEOLOGY Volume: 39 Issue: 2 Pages: 187-190 FEB 2011
Strontium isotopic composition (Sr-87/Sr-86) data from subfossil C-14-dated mollusk shells in raised beach sediments are used as
a paleosalinity proxy in the brackish Baltic Sea, the precision (+/- 5%) and accuracy (+/- 0.7%) of the method being judged from
replicate analyses of modern shells. Paleosalinity data with an average time resolution of similar to 200 yr for the period 7130-2775
calibrated C-14 yr B. P. indicate maximum surface salinities of 10%-11%, 11%-12%, and 12%-13% for the Bothnian Bay, Bothnian
Sea, and Baltic Proper (the three major Baltic subbasins). The relative salinity differences between the basins were small (<= 30%)
compared to the as much as eightfold present-day relative salinity differences (Bothnian Bay 1%-3%; Bothnian Sea 4%-5%; Baltic
Proper 6%-8%). Late Holocene freshening (ca. 3000 calibrated C-14 yr B. P. to present) is most pronounced in the northernmost
subbasin, the Bothnian Bay, consistent with the absence of a permanent halocline, sequestering of phosphorus in well-oxygenated
bottom sediments, and phosphorus limitation of primary production in the present-day Bothnian Bay. This study suggests that
paleosalinity data may be crucial to improving our understanding of the possible effects of any future, climate-induced freshening of
the Baltic Sea.
71. Crow, Ryan; Karlstrom, Karl; Asmerom, Yemane; et al.
Shrinking of the Colorado Plateau via lithospheric mantle erosion: Evidence from Nd and Sr isotopes and
geochronology of Neogene basalts //GEOLOGY Volume: 39 Issue: 1 Pages: 27-30 JAN 2011
Geochronologic data from the southern margins of the Colorado Plateau (western United States) show an inboard radial migration
of Neogene basaltic magmatism. Nd and Sr isotopic data show that as basaltic volcanism migrates inboard it also becomes
increasingly more asthenospheric. Strongly asthenospheric alkali basalt (epsilon(Nd) > 4) appeared on the western plateau margin
ca. 5 Ma, on the southeastern margin at 7 Ma, and is lacking from the plateau's other margins. Tomographic data suggest that lowvelocity mantle underlies almost all recent (younger than 1 Ma) basaltic volcanism in a ring around much of the Colorado Plateau at
a depth of 80 km. The combined isotopic and tomographic data indicate that the low-velocity mantle is asthenosphere along the
western and southeastern margins of the plateau, but modified lithosphere around the remaining margins. Temporal and spatial
patterns suggest a process by which upwelling asthenosphere is progressively infiltrating and replacing lithospheric mantle,
especially where Proterozoic boundaries exist. This model explains (1) the dramatic velocity contrast seen well inboard of the
physiographic edge of the plateau, (2) the inboard sweep of Neogene magmatism, and (3) isotopic evidence that much (but not all)
of the low-velocity mantle is asthenospheric. These data support models that ongoing uplift of the edges of the Colorado Plateau is
driven by mantle processes.
72. Kennedy, C. B.; Gault, A. G.; Fortin, D.; et al.
Carbon isotope fractionation by circumneutral iron-oxidizing bacteria //GEOLOGY Volume: 38 Issue: 12 Pages:
1087-1090
DEC 2010
Bacteriogenic iron oxides in natural environments are characterized by an abundance of ferrihydrite precipitates intermixed with
bacterial structures that commonly resemble those produced by the lithoautotrophic microorganisms Gallionella ferruginea and
Leptohtrix ochracea. These species have been inferred to play a causal role in the formation of bacteriogenic iron oxides, providing
a pathway for the reduction of CO2 and the depletion of C-13 in the organic constituents of bacteriogenic iron oxides. In this study,
stable carbon isotope fractionation was determined for bacteriogenic iron oxide samples collected from submarine hydrothermal
vents (Axial Volcano, Juan de Fuca Ridge), subterranean (Aspo Hard Rock Laboratory, Sweden) and surficial (Chalk River,
Canada) groundwater seeps, and cultures of G. ferruginea. Data were also collected from ferrihydrite samples lacking evidence of
bacteria from Bounty Seamount in the vicinity of Pitcairn Island. The mean delta C-13 (parts per thousand) of ferrihydrite was
determined to be -15.87 parts per thousand +/- 4.96 parts per thousand for the samples from Axial Volcano, -24.97 parts per
thousand +/- 0.43% for Aspo, -27.80 parts per thousand +/- 0.85 parts per thousand for Chalk River, -29.3 parts per thousand +/-
0.2 parts per thousand for the microbial culture, and -8.43 parts per thousand +/- 1.89 parts per thousand for the samples from
Pitcairn. Samples with the highest concentration of organic carbon also had the lightest delta C-13 in a logarithmic relationship. The
consistency of carbon isotope values in relation to the presence of iron-oxidizing bacteria from natural and laboratory samples is
interpreted as the ability of these microorganisms to fractionate carbon. The potential of this fractionation to serve as a biosignature
holds promise when the resistance of carbon and bacteriogenic ferrihydrite to diagenesis is taken into consideration.
73. Kuroda, Junichiro; Hori, Rie S.; Suzuki, Katsuhiko; et al.Marine osmium isotope record across the Triassic-Jurassic
boundary from a Pacific pelagic site //GEOLOGY Volume: 38 Issue: 12 Pages: 1095-1098
DEC 2010
The Triassic-Jurassic (T-J) boundary ca. 200 Ma represents one of the major mass extinction events of the Phanerozoic; however,
the cause of this event remains controversial because of a paucity of geological evidence. In this study we present an isotopic
record of osmium extracted from a bedded chert succession across the T-J boundary in the Kurusu section of Japan, deposited
within a Paleo-Pacific (Panthalassa) deep basin. The data show a gradual decrease in seawater Os-187/Os-188 values during the
Rhaetian, followed by a sharp increase in the latest Rhaetian, and a subsequent stable phase across the T-J boundary. The
decreasing trend of Os-187/Os-188 values during the Rhaetian indicates a gradual increase in the relative supply rate of
unradiogenic Os from the mantle associated with emplacement of the Central Atlantic Magmatic Province. The subsequent shift
toward radiogenic values reflects an increased supply of radiogenic Os due to enhanced continental weathering. This interval
marks more negative isotopic values of organic carbon, the onset of radiolarian faunal turnover, and conodont extinctions,
indicating that the rapid increase in continental weathering rate was closely linked to the perturbation of the carbon cycle and the TJ biotic crisis.
74. Finlay, Alexander J.; Selby, David; Osborne, Mark J.; et al.
Fault-charged mantle-fluid contamination of United Kingdom North Sea oils: Insights from Re-Os isotopes
//GEOLOGY Volume: 38 Issue: 11 Pages: 979-982 NOV 2010
United Kingdom North Sea oils sourced from the Kimmeridge Clay Formation contain unradiogenic (similar to 0.17 to similar to
0.48) and radiogenic (similar to 1.04 to similar to 3.34) Os-187/Os-188 values. The unradiogenic Os-187/Os-188 values are
spatially associated with the main basin-bounding faults of the Viking Graben and East Shetland Basin. In contrast, the radiogenic
Os-187/Os-188 values are associated with North Sea basins located farther away from the basin boundary faults. We suggest that
crustal thinning and strain localization within the Viking Graben and East Shetland Basin are sufficient to have allowed basinbounding faults to propagate to sufficient depth to act as conduits for mantle-derived fluids to interact with oil. This hypothesis is
supported by previous geochemical data for North Sea oil fields. Furthermore, we demonstrate the use of Os isotopes as an
important tracker of crustal-scale fluid dynamics and petroleum migration pathways in extensional basins.
75. Robinson, Stuart A.; Murphy, Daniel P.; Vance, Derek; et al.
Formation of "Southern Component Water" in the Late Cretaceous: Evidence from Nd-isotopes
//GEOLOGY Volume: 38 Issue: 10 Pages: 871-874 OCT 2010
Constraining deep-ocean circulation during past greenhouse climatic periods, such as the Cretaceous, is important for
understanding meridional heat transfer processes, controls on ocean anoxia, and the relative roles of climate and tectonics in
determining paleocirculation patterns. Ocean circulation models for the Late Cretaceous and early Paleogene suggest that
significant deep-water production occurred in the Southern Ocean, but cannot constrain when this process commenced or what the
temporal relationship was between opening tectonic gateways and Late Cretaceous climatic cooling. Nd-isotope data obtained from
biogenic apatite (fish teeth and bones) are presented from lower bathyal and abyssal sites in the South Atlantic and Indian Oceans.
During the mid-Cretaceous, relatively radiogenic Nd-isotope values suggest that deep-water circulation in these basins was
sluggish with inputs likely dominated by seawater-particle exchange processes and, possibly, easily weathered volcanic terranes.
In the Campanian-Maastrichtian the Nd-isotopic composition of proto-Indian and South Atlantic deep waters became less
radiogenic, suggesting the onset of deep-water formation in the Southern Ocean (Southern Component Water, SCW), consistent
with Paleogene reconstructions and ocean circulation models. A combination of Southern Hemisphere cooling and the opening of
tectonic gateways during the Campanian likely drove the onset of SCW.
76. Kasemann, Simone A.; Prave, Anthony R.; Fallick, Anthony E.; et al.
Neoproterozoic ice ages, boron isotopes, and ocean acidification: Implications for a snowball Earth//
GEOLOGY Volume: 38 Issue: 9 Pages: 775-778
SEP 2010
The Neoproterozoic Earth underwent at least two severe glaciations, each extending to low paleomagnetic latitudes and
punctuating warmer climates. The two widespread older and younger Cryogenian glacial deposits in Namibia are directly overlain
by cap carbonates deposited under inferred periods of high atmospheric carbon dioxide concentrations. Oceanic uptake of carbon
dioxide decreases ocean pH; here we present a record of Cryogenian interglacial ocean pH, based on boron ( B) isotopes in
marine carbonates. Our data suggest a largely constant ocean pH and no critically elevated pCO(2) throughout the older
postglacial and interglacial periods. In contrast, a marked ocean acidification event marks the younger deglaciation period and is
compatible with elevated postglacial pCO(2) concentration. Our data are consistent with the presence of two panglacial climate
states in the Cryogenian, but indicate that each had its own distinct environmental conditions.
77. Stap, Lucy; Lourens, Lucas J.; Thomas, Ellen; et al.High-resolution deep-sea carbon and oxygen isotope records
of Eocene Thermal Maximum 2 and H2 //GEOLOGY Volume: 38 Issue: 7 Pages: 607-610
JUL 2010
Eocene Thermal Maximum 2 (ETM2) and H2 were two short-lived global warming events that occurred similar to 2 m.y. after the
Paleocene-Eocene thermal maximum (PETM, ca. 56 Ma). We have generated benthic foraminiferal stable carbon and oxygen
isotope records of four sites along a depth transect on Walvis Ridge (similar to 3.5-1.5 km paleodepth, southeast Atlantic Ocean)
and one site on Maud Rise (Weddell Sea) to constrain the pattern and magnitude of their carbon isotope excursions (CIEs) and
deep-sea warming. At all sites, ETM2 is characterized by similar to 3 degrees C warming and a -1.4 parts per thousand CIE. The
H2 event that occurred similar to 100 k.y. later is associated with similar to 2 degrees C warming and a -0.8 parts per thousand
CIE. The magnitudes of the delta C-13 and delta O-18 excursions of both events are significantly smaller than those during the
PETM, but their coherent relation indicates that the delta C-13 change of the exogenic carbon pool was similarly related to warming
during these events, despite the much more gradual and transitioned onset of ETM2 and H2.
78. Martin, Victoria M.; Davidson, Jon; Morgan, Dan; et al.
Using the Sr isotope compositions of feldspars and glass to distinguish magma system components and
dynamics //GEOLOGY Volume: 38 Issue: 6 Pages: 539-542 JUN 2010
The individual components of magmatic rocks are being increasingly targeted to gain insight into volcanic systems. Here we
demonstrate the use of Sr isotope microsampling to distinguish distinct populations of glass and plagioclase that represent the
sources of components (liquids and crystals) within each erupted magma batch. We analyzed glasses and plagioclase feldspar
crystal cores to characterize crystal cargoes and host liquids from pumice-fall units from the Minoan cycle, Santorini, Greece. Using
this approach, we identify the magmatic components that interacted prior to eruption and formation of pumice clasts, allowing us to
interpret the magma dynamics associated with each eruption. Varying degrees of complexity can be identified, from relatively
simple cases where the crystals are in isotopic equilibrium with the glass, to more complex, such as the large caldera-forming
Minoan eruption, which is characterized by at least two liquid components and three different crystal provenances.
79. Canfield, Donald E.; Farquhar, James; Zerkle, Aubrey L.
High isotope fractionations during sulfate reduction in a low-sulfate euxinic ocean analog //GEOLOGY Volume:
38 Issue: 5 Pages: 415-418
MAY 2010
A detailed record of the early-Earth sulfur (S) cycle is chronicled by the S isotope values of sulfide and sulfate preserved in the rock
record. Interpretation of this record rests on our understanding of sulfur cycling in modern systems, experiments, and the resulting
isotopic signatures. Very large fractionations in delta S-34 of >= 70 parts per thousand are commonly measured between sulfide
and sulfate in modern systems and in ancient sediments. Theoretical calculations suggest that sulfate-reducing prokaryotes are
capable of producing such large fractionations during the reduction of sulfate to sulfide, although they have only been
demonstrated to generate fractionations up to 48 parts per thousand. Here we report the first direct determination of 60 parts per
thousand-70 parts per thousand fractionations by natural populations of sulfate reducers. These high fractionations occur under the
relatively low-sulfate conditions (1.1-2 mM) of meromictic Lago di Cadagno in Switzerland. The major and minor isotopic
composition of sulfide and sulfate in the lake water is consistent with sulfide produced by sulfate reduction, with little evidence for
modification by further oxidative sulfur cycling. These observations help us to constrain the evolution of seawater sulfate
concentrations.
80. Horikawa, Keiji; Asahara, Yoshihiro; Yamamoto, Koshi; et al.
Intermediate water formation in the Bering Sea during glacial periods: Evidence from neodymium isotope
ratios //GEOLOGY Volume: 38 Issue: 5 Pages: 435-438 MAY 2010
Changes in the flux and location of overturning circulation may have large effects on marine ecosystems and CO2 exchange
between the ocean and atmosphere. However, unlike the Atlantic, little is known about ocean circulation and ventilation under
glacial boundary conditions in the North Pacific, especially in regard to intermediate water circulation. Here we present new records
of neodymium (Nd) isotopes (epsilon(Nd)) in Fe-Mn oxyhydroxides of Bering Sea sediments (884 m water depth). We found a
systematic variation between radiogenic values (up to +0.8 epsilon(Nd)) during cold periods and relatively less radiogenic values
(<-1 epsilon(Nd)) during warm periods. There are no water masses with such radiogenic Nd isotope signatures in the intermediate
or deep North Pacific. Potential sources of radiogenic values in the subarctic North Pacific are limited to surface waters adjacent to
the Aleutian Arc and Kamchatka Peninsula. Therefore, the radiogenic epsilon(Nd) values of Fe-Mn oxyhydroxides observed at the
intermediate depth during glacial periods are best explained by subduction of the surface water to the intermediate depth (at least
similar to 800 m) due to brine rejection. Our data strongly indicate that the northwestern Bering Sea (off northeastern Kamchatka)
was a possible source region of glacial intermediate water in the Bering Sea and the subarctic North Pacific.
81. Montoya-Pino, Carolina; Weyer, Stefan; Anbar, Ariel D.; et al.
Global enhancement of ocean anoxia during Oceanic Anoxic Event 2: A quantitative approach using U
isotopes //GEOLOGY Volume: 38 Issue: 4 Pages: 315-318 APR 2010
During the Mesozoic greenhouse world, the oceans underwent several oceanic anoxic events (OAEs) characterized by intervals
during which organic-rich black shales were deposited, indicating strong oxygen depletion in the marine realm. The CenomanianTuronian OAE2 (ca. 93 Ma) represents one of the most prominent events of the Cretaceous, with significant perturbations of the
global carbon cycle. Although OAE2 likely reached a global scale, the spatial extent of seawater anoxia during this OAE is poorly
constrained. Here we demonstrate that variations in the U-238/U-235 isotope ratio (delta U-238), a newly developed paleoredox
proxy, can be used to quantify the extent of marine anoxia. For black shales from the mid-Cretaceous OAE2 we find a systematic
shift toward lighter delta U-238 and lower U concentrations as compared to modern equivalent organic-rich sediments from the
Black Sea. This shift translates to a global increase of oceanic anoxia during OAE2 by at least a factor of three as compared to the
present day or to periods before and after OAE2. The constant offset in U concentrations and isotope compositions of black shales
throughout OAE2 compared to modern Black Sea sediments indicates an enhancement of oceanic anoxic conditions already prior
to the onset of OAE2.
82. Cai, Yanjun; Cheng, Hai; An, Zhisheng; et al.
Large variations of oxygen isotopes in precipitation over south-central Tibet during Marine Isotope Stage 5
//GEOLOGY Volume: 38 Issue: 3 Pages: 243-246 DOIMAR 2010
Oxygen isotope (delta O-18) records of two stalagmites from Tianmen Cave, on the south-central Tibetan Plateau, grew during
much of Marine Isotope Stage 5. The Tianmen record, the first cave record from the Tibetan Plateau, characterizes a precipitation
delta O-18 history larger in amplitude but similar in structure to Asian Monsoon records from the adjacent regions, providing
essential evidence that the Asian Monsoon system, including the East Asian and Indian Monsoon subsystems, responds largely to
changes in Northern Hemisphere summer insolation. Extremely low delta O-18 values during Marine Isotope Stages 5a, 5c, and 5e
suggest that precipitation, rather than temperature, was a major factor controlling delta O-18 in precipitation on orbital time scales in
the south-central Tibetan Plateau. The Tianmen record may help in the interpretation of regional ice core delta O-18 records. The
large range of orbital-scale shifts in meteoric delta O-18 (>9%) raises important considerations related to reconstructing the uplift
history of the plateau.
83. Parnell, John; Boyce, Adrian; Thackrey, Scott; et al.
Sulfur isotope signatures for rapid colonization of an impact crater by thermophilic microbes
//GEOLOGY Volume: 38 Issue: 3 Pages: 271-274 MAR 2010
In the 23-km-diameter Haughton impact structure, Canadian High Arctic, in sulfate-rich bedrock, widespread hydrothermal sulfide
mineralization occurred in breccias formed during the impact. The sulfides exhibit extreme sulfur isotopic fractionation relative to the
original sulfate, requiring microbial sulfate reduction by thermophiles throughout the crater. This evidence of widespread microbial
activity demonstrates that colonization could occur within the lifetime of a moderately sized, impact-induced hydrothermal system.
The pyrite was subsequently oxidized to jarosite, which may also have been microbially mediated. The successful detection of
evidence for microbial life suggests that it would be a valuable technique to deploy in sulfate-rich impact terrain on Mars.
84. Price, Gregory D.; Nunn, Elizabeth V.Valanginian isotope variation in glendonites and belemnites from Arctic
Svalbard: Transient glacial temperatures during the Cretaceous greenhouse //GEOLOGY Volume: 38 Issue: 3
Pages: 251-254
MAR 2010
Oxygen and carbon isotope data from Cretaceous (Valanginian) glendonites and belemnites from Arctic Svalbard are presented.
Oxygen isotope data from well-preserved glendonites, in conjunction with the ikaite to glendonite pseudomorph transition
temperature, are used to provide an estimate of the oxygen isotope composition of ambient seawater. Calculation of such a factor
is essential for robust paleotemperature estimates. Using this methodology, our paleotemperatures calculated from the oxygen
isotope compositions of coexisting belemnites yield cool temperatures (4-7 degrees C) consistent with transient glacial polar
conditions during the Cretaceous greenhouse. Cool polar temperatures during the Cretaceous help reconcile geologic data with the
simulations of general circulation models. Nevertheless, beyond this postulated and transient cool event within the Valanginian, the
remainder of the isotope data are interpretable in terms of warm polar conditions during the Cretaceous greenhouse.
85. Amiot, Romain; Buffetaut, Eric; Lecuyer, Christophe; et al.Oxygen isotope evidence for semi-aquatic habits among
spinosaurid theropods //GEOLOGY Volume: 38 Issue: 2 Pages: 139-142
FEB 2010
Spinosaurs were large theropod dinosaurs showing peculiar specializations, including somewhat crocodile-like elongate jaws and
conical teeth. Their biology has been much discussed, and a piscivorous diet has been suggested on the basis of,jaw as well as
tooth morphology and stomach contents. Although fish eating has been considered plausible, an aquatic or semiaquatic lifestyle
has seldom been suggested because of the apparent lack of corresponding adaptations in the postcranial skeleton of spinosaurs,
which on the whole is reminiscent of that of other large terrestrial theropods. On the basis of the oxygen isotopic composition of
their phosphatic remains compared with those of coexisting terrestrial theropod dinosaurs and semiaquatic crocodilians and turtles,
we conclude that spinosaurs had semiaquatic lifestyles, i.e., they spent a large part of their daily time in water, like extant
crocodilians or hippopotamuses. This result sheds light on niche partitioning between large predatory dinosaurs, since spinosaurs
coexisted with other large theropods such as carcharodontosaurids or tyrannosaurids. The likely ichlhyophagy and aquatic habits of
spinosaurids may, have allowed them to coexist with other large theropods by reducing competition for food and territory.
86. Arehart, Greg B.; DeYoung, Susan; Poulson, Simon R.; et al.
Sulfur Isotopes in Plutonic Rocks of the Great Basin Indicators of Crustal Architecture //JOURNAL OF
GEOLOGY Volume: 121 Issue: 4 Pages: 355-369
JUL 2013
Reconstructions of geologic provinces in the crust are an important component of understanding ancient plate tectonic processes
and crustal evolution. Isotopic data from plutonic rocks, primarily Sr, Nd, Pb, and O, have been commonly utilized to delineate
ancient geological provinces. Sulfur isotopes have not previously been utilized for province reconstruction, perhaps because of the
difficulty in analysis and interpretation. We present here the results of the first large-scale effort at utilizing sulfur isotopes as an
indicator of crustal architecture and demonstrate that sulfur is complementary to other isotopic measurements. We also show that,
because of mass balance considerations, sulfur can be potentially a far more sensitive indicator of magma-crust interaction
processes during magma migration through the crust than are other isotope systems. We anticipate that addition of sulfur isotope
measurements to other studies of crustal evolution will provide significant insights into plate tectonics and crustal evolution in many
areas of the world.
87. Zhang, Kai-Jun; Li, Bing; Wei, Qing-Guo Diversified Provenance of the Songpan-Ganzi Triassic Turbidites,
Central China: Constraints from Geochemistry and Nd Isotopes //JOURNAL OF GEOLOGY Volume: 120 Issue: 1
Pages: 69-82
JAN 2012
The Songpan-Ganzi Complex (SGC) in central China is one of the largest turbidite basins on Earth, but the origin of slates and
sandstones is still open to debate. Petrographic, geochemical, and Nd isotope data for representative turbidites were collected, and
the SGC was thus divided up into four main zones. The western and middle zones are characterized by easterly paleocurrents,
abundant high-pressure (HP)-related dense minerals, and low chemical index of alteration (CIA) and Th/U values. The samples
from the western zone have strongly negative epsilon(Nd) values, old Nd model ages, and low ferromagnesian but high felsic
contents. The sediments from the middle zone have intermediate epsilon(Nd) values and Nd model ages and trace elemental
ratios. No HP-related dense minerals have been identified in the eastern zone, which is dominated by westerly paleocurrents, with
intermediate Nd isotopic and geochemical values. The northernmost zone is characterized by high epsilon(Nd) (0) values, young
T(DM) ages, and high ferromagnesian but low felsic contents. Geochemical and Nd isotopic data all are suggestive of an overall
silicic provenance of the sediments, which have not been homogenized by recycling. Several source rocks for the samples are
identified, and they include sedimentary rocks, ophiolites, silicic igneous rocks, and HP metamorphic rocks. Nd isotopes and
geochemical indices least susceptible to change by sedimentary processes indicate that turbidites in the SGC were dominantly
derived from central Qiangtang, Dabie-Qinling, and Kunlun. The low CIA values and Th/U ratios indicate that the source areas for
the western SGC could have been elevated by tectonism and dominated by cool and/or arid climates.
88. Cucciniello, Ciro; Langone, Antonio; Melluso, Leone; et al.
U-Pb Ages, Pb-Os Isotope Ratios, and Platinum-Group Element (PGE) Composition of the West-Central
Madagascar Flood Basalt Province //JOURNAL OF GEOLOGY Volume: 118 Issue: 5 Pages: 523-541 SEP 2010
The Mailaka lava succession (central-western Madagascar) forms part of the Madagascar large igneous province and is
characterized by basaltic to picritic basalt lava flows and minor evolved flows. In situ U-Pb dating of zircon in rhyodacites yields
concordant ages of 89.7 +/- 1.4 and 90.7 +/- 1.1 Ma. Therefore, the capping rhyodacitic unit of the Mailaka lava succession was
emplaced just after the underlying basalt sequence (dated paleontologically at Coniacian-Turonian). Two geochemically different
lava series are present. A transitional series ranging from picritic basalts to basalts has incompatible element abundances and Pb,
Os, and Nd isotope ratios within the range of mid-ocean ridge basalts. In addition, the concentrations of platinum-group elements (Ir
< 0.35 ng/g, Ru < 0.17 ng/g, Pd = 1.0-1.6 ng/g) in the transitional basalts are generally lower than in basaltic lavas from oceanic
plateaus (e.g., Ontong Java and Kerguelen) and other continental flood basalt provinces (e.g., Deccan and Etendeka). A tholeiitic
series ranges from picritic basalts to rhyodacites and has relatively high concentrations of trace elements (e.g., Rb, Ba, Th, and
light lanthanides) and the Pb-Sr-Nd and Os isotopic characteristic of magmas that have assimilated continental crust. The Pb
isotope ratios of tholeiitic andesites indicate the involvement of a component highly depleted in radiogenic Pb, very likely old lower
crust. Energy-constrained-assimilation-fractional-crystallization modeling indicates that the rhyodacites may be the result of similar
to 25% assimilation of upper continental crust, with a ratio between assimilated mass and subtracted solid of similar to 0.35. An
andesite with low Pb isotope ratios may be the result of similar to 8% assimilation of lower continental crust with a mass
assimilated/mass accumulated ratio of similar to 0.1. Interaction of mantle-derived magmas with crustal lithologies of different age
and evolutionary history thus occurred in this sector of the flood basalt province. Contamination of mantle-derived rocks by material
of different crustal domains is a process also observed in other large igneous provinces, such as the Deccan Traps.
89. Rehnstrom, Emma F.
Prolonged Paleozoic Magmatism in the East Greenland Caledonides: Some Constraints from U-Pb Ages and
Hf Isotopes //JOURNAL OF GEOLOGY Volume: 118 Issue: 5 Pages: 447-465 SEP 2010
New U, Pb, and Hf isotopic data from thermal ionization mass spectrometry and inductively coupled plasma mass spectrometry
from intermediate calc-alkaline rocks in the Caledonides of central East Greenland provide new evidence of a prolonged period of
Paleozoic subduction-related magmatism. The new data point toward two groups of plutons: one older generation crystallizing at
ca. 450 Ma and a younger generation at ca. 423 Ma. There is additionally a titanite-forming event at ca. 440 Ma. The Hf isotopes of
the younger group have a larger variation and less juvenile character than those of the older group, but data indicate a mixed
source with both crustal and mantle components for both groups. These new data combined with already published
geochronological data testify to a prolonged and complex magmatic history starting markedly earlier in the southernmost segment
of the East Greenland Caledonides than farther north. The varied geochemical compositions of the plutons and the prolonged
intrusive activity are in contrast to the short-lived homogeneous S-type leucogranitic magmatism found elsewhere in the East
Greenland Caledonides and bear more similarities to arc-related terranes now found in the Irish, Scottish, and Scandinavian
Caledonides. It is speculated that the earlier plutons in East Greenland represent the northernmost expression of continental arcs
formed in a west-directed subduction system along the full length of the Laurentian margin in the Paleozoic. The later plutons
formed concomitant with leucogranite intrusions within a collisional setting.
90. Clyde, William C.; Ting, Suyin; Snell, Kathryn E.; et al.
New Paleomagnetic and Stable-Isotope Results from the Nanxiong Basin, China: Implications for the K/T
Boundary and the Timing of Paleocene Mammalian Turnover //JOURNAL OF GEOLOGY Volume: 118 Issue: 2
Pages: 131-143
MAR 2010
The Nanxiong Basin (Guangdong Province, China) preserves the most complete Asian stratigraphic record of the CretaceousPaleogene (K/Pg) boundary extinction and the subsequent Paleocene mammalian radiation. Despite extensive study, the precise
placement of the K/Pg boundary in the Nanxiong Basin sequence has been controversial, and the timing of subsequent mammalian
turnover is poorly constrained. We present new paleomagnetic and geochemical data from the Late Cretaceous Pingling Formation
(Nanxiong Group) and the overlying Paleocene Shanghu, Nongshan, and Guchengcun formations (Luofozhai Group). Our samples
are directly correlated with previous geochemical and paleontological sampling localities, allowing for easy comparison with other
local proxy records. Results indicate that the traditional placement of the K/Pg boundary at the base of a chaotic channel sandstone
bed marking the highest stratigraphic appearance of dinosaur eggshell fragments and lowest stratigraphic appearance of
Paleocene mammalian fossils lies about two-thirds of the way up Chron C29R, consistent with the placement of the boundary in all
other well-documented sections. The average carbon isotope composition of paleosol carbonates decreases by >2 parts per
thousand in the Early Paleocene, consistent with a major disruption to global carbon cycling after the K/Pg boundary. Constraints
on the age of the first major Cenozoic mammalian turnover event in Asia (the Shanghuan-Nongshanian Asian Land Mammal Age
boundary) support its placement near the top of Chron C27N, which coincides with a similar turnover in North America and
geochemical changes recorded in several deep sea cores.
91. Makhnach, A. A.; Kuleshov, V. N.; Vinogradov, V. I.; et al.
Carbon, oxygen, and sulfur isotope compositions of carbonate and sulfate rocks from the Famennian
potassium-bearing subformation of the Pripyat trough //LITHOLOGY AND MINERAL RESOURCES Volume: 48
Issue: 4 Pages: 327-342
JUL 2013
Peculiar features of evaporitic process at the stage of potassium accumulation are considered on the basis of carbon and oxygen
isotope data on carbonate rocks and sulfur isotope data on anhydrite from the Famennian potassium-bearing subformation of the
Starobin potassic salt deposit in the Pripyat trough. It was found that potassium accumulation was accompanied by the influx of
continental waters and highly concentrated brines, while the formation of thick salt-free units was related to the replenishment of
fresh seawater to the basin.
92. Malov, A. I.
Application of geological benchmarks for determining groundwater residence time in the aquifer based on
uranium isotope data: Evidence from the Severnaya Dvina Basin //LITHOLOGY AND MINERAL
RESOURCES Volume: 48 Issue: 3 Pages: 254-265
MAY 2013
Using the Severnaya Dvina Basin as an example, it is shown that information on the distribution of natural U isotopes in aquifers
can be applied for practical estimation of the duration of interaction between groundwater and host rocks (age of groundwater). The
proposed calculation method includes preliminary determination of the generalized calculated parameter (probability of the transfer
of U-234 excess to water) based on geological benchmarks, hydrodynamic calculations, and paleohydrogeological reconstructions.
It is assumed that this probability is constant for aquifers composed of homogeneous rocks with certain lithological composition and
oxidizing conditions for U. The obtained correlations are valid for a model, where water entering the aquifer lacks U. If it contains
such U, the "transport" time, which is equivalent to the timing of respective concentrations and isotopic ratios in the aquifer unit, is
determined and estimates of the "water-rock" interaction in the aquifer unit are corrected.
93. Kuznetsov, A. B.; Gorokhov, I. M.; Melezhik, V. A.; et al.
Strontium isotope composition of the lower proterozoic carbonate concretions: The Zaonega Formation,
Southeast Karelia //LITHOLOGY AND MINERAL RESOURCES Volume: 47 Issue: 4 Pages: 319-333 JUL 2012
The middle part of the volcanosedimentary Zaonega Formation of the Ludikovian Suprahorizon (approximately 2.0 Ga) includes
large carbonates concretions and lenses in shungite layers. Carbonate lenses and concretions are primarily elongated and
flattened, and their thickness varies from tens of centimeters to a few meters. Some lenses retain relicts of lamination. Concretions
are composed of calcite or dolomite. They contain abundant organic matter, as well as mica, talc, chlorite, quartz, and pyrite
crystals. The calcite concretions contain some dolomite admixture (Mg/Ca = 0.011-0.045) and differ from sedimentary limestones
by a low Fe/Mn value (0.3-2.1). The Sr content is as much as 385-505 mu g/g in most samples and is low (86 mu g/g) only in one
sample. The Rb-Sr systematics of carbonate concretions was studied with the stepwise dissolution procedure, which included
processing with the ammonium acetate solution (AMA fraction) to partially remove the secondary carbonate material, with
dissolution of the residue in acetic acid (ACA fraction). In individual calcite samples, discrepancy between the measured Sr-87/Sr86 values in the AMA and ACA calcite fractions shows a variation range of 0.0008-0.0033. The initial Sr-87/Sr-86 ratio in the ACA
fractions of the studied samples varies from 0.7053 to 0.7162. The ratio shows a positive correlation with Mg/Ca and the proportion
of siliciclastic admixture and negative correlation with the Mn content. The concretions were formed when the sediments subsided,
probably, during the transition from a zone with "mild" reductive conditions to zones with active sulfate reduction and
methanogenesis. In the sulfate reduction zone, where most pyrite-bearing concretions were formed, the sediment was not
geochemically exchaged with the bottom water and was evolved into a closed or semiclosed system. Processes of diagenesis in
this zone promoted the release of the radiogenic Sr-87 from the associated siliciclastic minerals, resulting in growth of the initial Sr87/Sr-86 in concretions up to 0.7108-0.7162. Some calcite concretions, which lacked pyrite (or contained its minimal amount) were
likely formed in a thin surficial sediment layer located above the sulfate reduction zone. Therefore, they precipitated Sr in isotope
equilibrium with Sr of the bottom water. However, large concretions and carbonate lenses with an insignificant siliciclastic admixture
could retain the signature of early diagenesis or even sedimentation. The initial Sr-87/Sr-86 ratio in one of such samples with the
siliciclastic admixture of 6.2% makes it possible to estimate the maximal value of this ratio (0.7053) in the Ludikovian paleobasin.
94. Lein, A. Yu.; Rusanov, I. I.; Kravchishina, M. D.; et al Genesis of organic and carbonate carbon in sediments of the
North and Middle Caspian basins inferred from the isotope data //LITHOLOGY AND MINERAL
RESOURCES Volume: 47 Issue: 4 Pages: 281-293 JUL 2012
Isotopic compositions of organic (delta C-13-C-org) and carbonate (delta C-13-C-carb) carbon were analyzed in the particulate
matter (hereafter, particulates) and sediments from the North and Middle Caspian basins. Isotopic composition of C-org was used
for assessing proportions of the allochthonous and autochthonous organic matter in the particulates. Difference between the delta
C-13-C-org values in surface sediments and particulates is explained by the aerobic and anaerobic diagenetic transformations.
Isotopic composition of C-org in sediments may be used as a tool for reconstructing the Quaternary transgressive-regressive
history of the Caspian Sea.
95. Groundwater Hydrology and Stable Isotope Analysis of an Open-System Pingo in Northwestern Mongolia
//
Author(s): Yoshikawa, Kenji; Natsagdorj, Sharkhuu; Sharkhuu, Anarmaa
Source: PERMAFROST AND PERIGLACIAL PROCESSES Volume: 24 Issue: 3 Pages: 175-183
JUL 2013
The first record of stable isotopes through a complete sequence of ice within an open-system pingo in northwestern Mongolia
indicates a complex history of ice formation and pingo growth. A continuous section of ice 32 m long was cored through the centre
of Mongot Pingo, and ice cores were analysed for stable isotopes and chemical composition. Two different stable isotope patterns
in separate ice sections are identified: 1 open-system freezing and 2 semi-closed system (or closed system) freezing. Discharge
measurements were observed in 2009 after drilling through pingo ice to artesian sub-pingo water and compared with data collected
from the same pingo in 1968. Approximately 850-950 m(3) of sub-pingo water discharged within 120 h during drilling in both 1968
and 2009, a volume equivalent to about 10 per cent of the current pingo ice volume. Between 1968 and 2009, permafrost (pingo
ice) thickened by about 60 cm (1.46 cm per year), from 32.0 to 32.6 m, due to the decrease in sub-pingo artesian water pressure
after water release from the 1968 drilling. The major mechanism for ice formation at this pingo is groundwater artesian pressure,
though not continuously. Four major stages of pingo growth after 8790 yr BP are inferred.
96. Lacelle, Denis; Vasil'chuk, Yurij K.
Recent Progress (2007-2012) in Permafrost Isotope Geochemistry //PERMAFROST AND PERIGLACIAL
PROCESSES Volume: 24 Issue: 2 Pages: 138-145
APR 2013
This paper reviews contributions to permafrost isotope geochemistry published between 2007 and 2012 and proposes future
research directions. It focuses on: (1) the origin and age of ground ice; (2) geochemistry and water movement in the active and
transient layers; and (3) geochemistry and water movement in deep permafrost. The use of isotope geochemistry to study
permafrost-related processes has grown significantly over the last few years. These processes have been elucidated by combining
geochemical and isotope measurements from different components of permafrost. Such combination has yielded new insights, for
example, into the water source and transfer processes that lead to the formation of ground ice, as well as groundwater movement
and residence time in permafrost. Permafrost isotope geochemistry has a promising future and should provide valuable tools for the
study of a rapidly changing permafrost environment.
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spec. iss. ). - Библиогр. в конце докл.
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98. Applications of non-traditional stable isotopes in high-temperature geochemistry / guest ed.
Feineman Maureen [et al.].-Amsterdam [etc.] : Elsevier, 2009. - 103, [4] c. : ил., к., портр., табл. (Chemical geology, ISSN 0009-2541; vol. 258, iss. 1-2, spec. iss. ). - Библиогр. в конце докл.
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99. Handbook of stable isotope analytical techniques. Vol. 2. - 2009. - XXIII, 1372 c. : ил., табл. - ISBN
978-0-444-51115-7.
100. Симпозиум по геохимии изотопов имени академика А.П. Виноградова (18; 2007; Москва).
XVIII симпозиум ..., 14-16 нояб. 2007 г., Москва : тезисы докладов / Рос. акад. наук, Отд-ние наук
410/2351-0
о Земле, Науч. совет по проблемам геохимии, Ин-т геохимии и аналит. химии им. В.И.
Вернадского. - [СПб., 2007]. - 302 с. : ил. - Библиогр. в конце докл.
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101. Physics, carbon dioxide, trace elements and isotopes in the Southern Ocean: the Polarstern
expeditions ANT XXIV-3 (2008) and ANT XXIII / 3 (2006) / guest ed. Fachbach Eberhard [et al.]. Amsterdam [etc.] : Elsevier, 2011. - C. 2497-2784, [2] : ил., табл. - (Deep-sea research. Pt II, Topical
studies in oceanography; ISSN 0967-0645; vol. 58, iss. 25-26 ). - Библиогр. в конце ст.
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102.Stable isotopes in water body on the Tibetan plateau. - Beijing : Science in China press; Heidelberg
: Springer, 2009. - C. 2723-2910, [2] : ил., к., табл. - (Chinese science bulletin, ISSN 1001-6538; vol. 54,
iss. 16, spec. topic ). - Библиогр. в конце ст.
103. ПОЛИСТАДИЙНЫЕ ПРЕОБРАЗОВАНИЯ ВЫСОКОУГЛЕРОДИСТЫХ ПОРОД ЛЮДИКОВИЯ ОНЕЖСКОГО ПРОГИБА//
Гольцин Н.А., Лохов К.И., Капитонов И.Н., Полеховский Ю.С., Лобиков А.Ф., Сергеев С.А.
Региональная геология и металлогения. 2010. № 41. С. 61-74
Изотопные характеристики высокоуглеродистых пород людиковия, полученные ранее различными
исследователями, не указывают однозначно на условия формирования и возраст этих пород. Нами
изучены вариации изотопного состава стабильных изотопов (шунгитового углерода, углерода и
кислорода в карбонатах и серы в сульфидах), U-Pb система пород и минералов, спектры
распределения редкоземельных элементов, а также изотопная гафний-неодимовая систематика.
Впервые установлены возрастные этапы преобразования метаосадочных и метавулканических
пород людиковия. Показана мультистадийность геологических событий в высокоуглеродистых
породах Онежской структуры.
104. Колесников Е.М., Колесникова Н.В.
ПРИЗНАКИ КОМЕТНОГО ВЕЩЕСТВА НА МЕСТЕ ТУНГУССКОГО ПАДЕНИЯ 1908 Г//
Астрономический вестник. 2010. Т. 44. № 2. С. 123-134
Представлен краткий обзор многолетних работ авторов и их коллег, которые привели к
обнаружению следов кометного вещества в торфе в эпицентре Тунгусской катастрофы 1908 г.
В катастрофных слоях торфа, включающих прирост 1908 г., на пяти торфяниках в эпицентре
взрыва Тунгусского космического тела обнаружены сдвиги в изотопном составе водорода и
углерода относительно их значений для верхних и нижних слоев той же колонки. Эти сдвиги
не могут быть объяснены земными причинами – консервацией в торфе минеральной и
органической пыли, гумификацией торфа, выделением из Земли углеводородных газов,
климатическими изменениями и другими физико-химическими причинами. В катастрофных
слоях контрольных колонок торфа изотопные сдвиги отсутствуют. Изотопные данные
хорошо совпадают с повышенным содержанием в тех же слоях торфа иридия и др. элементов
платиновой группы, надежно фиксирующих присутствие космического вещества в земных
объектах. Космогенный характер изотопных эффектов подтверждается присутствием в
катастрофных слоях “мертвого” углерода, не содержащего радиоактивный 14. Чтобы
объяснить наблюдаемые сдвиги в изотопном составе углерода, космический углерод,
законсервированный в торфе, по изотопному составу должен быть сверхтяжелым – по
расчетам от +50 до +60 . Такой изотопно тяжелый углерод отсутствует как на Земле, так
и в обычных метеоритах. Он встречается только в отдельных минеральных фазах углистых
хондритов типа СI, близких по химическому составу к кометарной пыли. Соотношение
содержания иридия и других платиноидов и редкоземельных элементов также указывает на
кометарную природу ТКТ. В околокатастрофных слоях торфа было обнаружено аномальное
увеличение содержания многих летучих элементов, также показывающее, что ТКТ было
ядром кометы. Исследования содержания и изотопного состава азота в торфе выявили следы
мощных кислотных дождей, вызванных пролетом и взрывом ТКТ.
105. Савко К.А., Кориш Е.Х., Пилюгин С.М.
МЕТАМОРФИЧЕСКИЕ РЕАКЦИИ ОБРАЗОВАНИЯ REE-МИНЕРАЛОВ В УГЛЕРОДИСТЫХ СЛАНЦАХ ТИМ-ЯСТРЕБОВСКОЙ
СТРУКТУРЫ, ВОРОНЕЖСКИЙ КРИСТАЛЛИЧЕСКИЙ МАССИВ//
Вестник Воронежского государственного университета. Серия: Геология. 2009. № 2. С. 93-109
В палеопротерозойских углеродистых сланцах Тим-Ястребовской структуры установлена REEминерализация, представленная силикатами - алланит, торит, хаттонит; фтор-карбонатами -
бастнезит, синхизит; фосфатами - монацит, ксенотим, REE-содержащий апатит. Реакционные
структуры с участием бастнезита и алланита предполагают, что бастнезит был источником
LREE-элементов для образования более высокотемпературных алланита и монацита. Это
подтверждается распределением REE-элементов в монаците, алланите и бастнезите, которые
почти не отличаются друг от друга и характеризуются резким преобладанием легких REEэлементов. Многочисленные включения и структуры замещения апатита монацитом
предполагают участие REE-обогащенного апатита в образовании монацита. Смену LREEминералов при зональном метаморфизме в диапазоне 350-550 °С можно описать как серию
последовательных переходов: 1) Mnz → Aln, Bst → Aln и 2) Bst → Mnz, ApLREE → Mnz,
интерпретируемых проградными метаморфическими реакциями.
106. Кострова С.С., Майер Х., Чаплыгин Б., Безрукова Е.В.
ИЗОТОПНЫЕ ХАРАКТЕРИСТИКИ ОЗЕРА КОТОКЕЛЬ//
Вестник Иркутского государственного технического университета. 2012. Т. 68. № 9. С. 62-68.
Представлены результаты изотопного анализа кислорода ископаемых створок диатомовых
водорослей, а также стабильных изотопов воды озера Котокель. Установлено, что значения 18О
створок, извлеченных из голоцено-вых отложений, изменяются от 23,7 до 30,3‰. Показано, что
изотопный состав кислорода створок озера Кото-кель, главным образом, определяется изотопным
составом озерной воды. Вариации величины 18О воды озера вызваны изменением изотопного
состава атмосферных осадков, выпадающих в регионе, уровнем испарения воды из озера,
количеством талой воды, поступающей в озеро с реками.
107. Токарев И.В., Зубков А.А., Румынин В.Г., Поздняков С.П.
ОЦЕНКА ДОЛГОСРОЧНОЙ БЕЗОПАСНОСТИ ЗАХОРОНЕНИЯ РАДИОАКТИВНЫХ ОТХОДОВ. 2. ИССЛЕДОВАНИЕ ВОДООБМЕНА
В МНОГОСЛОЙНОЙ СИСТЕМЕ ИЗОТОПНЫМИ МЕТОДАМИ//
Водные ресурсы. 2009. Т. 36. № 3. С. 363-374.
В дополнение к ранее выполненным исследованиям изотопных систем 3, 2, 18, Ar, 40Ar/36Ar и
234 238
U/ U дается количественная интерпретация данных уран-гелиевого метода датирования
подземных вод на полигоне захоронения радиоактивных отходов Сибирского химического
комбината. В основу интерпретации положены аналитические модели, в которых учитывается
подток глубинного гелия, а также диффузионно-конвективный межслоевой обмен. Расчетные
значения скорости фильтрации в пластах-коллекторах и буферных горизонтах в целом
согласуются с ранее выполненными гидродинамическими оценками. На основе полученных
значений скоростей горизонтального массопереноса выполнена оценка возраста подземных вод в
точках отбора проб. В нижних (II и III) горизонтах, куда происходит нагнетание радиоактивных
отходов, возраст воды варьирует от 7 до 14 (среднее значение
2 до 4, в верхнем горизонте V – от 1 до 2 тыс. лет.
9), в буферном горизонте IV – от
108. Аникина Е.Ю., Гамянин Г.Н., Бортников Н.С.
ИЗОТОПНЫЙ СОСТАВ СЕРЫ СУЛЬФИДОВ СЕРЕБРОРУДНОГО МЕСТОРОЖДЕНИЯ МАНГАЗЕЙСКОЕ (ВОСТОЧНАЯ ЯКУТИЯ,
РОССИЯ)//
Геология рудных месторождений. 2010. Т. 52. № 6. С. 534-552.
Проведено исследование последовательности формирования рудных зон и соотношения изотопов
серы сульфидов серебро-рудного месторождения Мангазейское. Месторождение локализовано в
зоне Нюектаминского разлома в восточном крыле Эндыбальской антиклинали. Рудные зоны
залегают в среднекарбоновых–среднеюрских терригенных толщах Верхоянского комплекса,
которые прорываются породами Эндыбальского субвулканического штока и дайками кислого и
основного состава. Выделено три рудных этапа минералообразования: золото-редкометальный(I),
касситерит-сульфидный(II) и серебро-полиметаллический(III). Продукты этих этапов разобщены в
пространстве. Значения 34S сульфидов изменяются в целом от –6.4 до +8.0 . Для золоторедкометального этапа эта величина варьирует от –1.8 до +4.7 , для касситерит-сульфидного от
–6.4 до +6.6 и серебро-полиметаллического от –5.6 до +8.0 . Использование серо-изотопного
геотермометра позволило получить температуры минералообразования 315–415°С для II этапа и
125–280°С для III этапа. Рассмотрены различные причины изменения изотопного состава
сульфидов. Показано, что полученные данные о соотношении изотопов серы лучше всего
интерпретировать как участие в процессе минералообразования двух флюидов: магматогенного (
S
0) и низкотемпературного, заимствовавшего серу из вмещающих пород ( 34S 0). На
последних этапах формирования месторождения существенную роль в образовании рудных зон
играли такие процессы, как вскипание и смешение магматогенного флюида с разогретыми
метеорными водами.
34
109. Галимов Э.М.
ОБРАЗОВАНИЕ ЛУНЫ И ЗЕМЛИ ИЗ ОБЩЕГО СУПРАПЛАНЕТНОГО ГАЗО-ПЫЛЕВОГО СГУЩЕНИЯ (ДОКЛАД НА XIX
ВСЕРОССИЙСКОМ СИМПОЗИУМЕ ПО ГЕОХИМИИ ИЗОТОПОВ 16 НОЯБРЯ 2010 Г.)//
Геохимия. 2011. № 6. С. 563-580
Предлагается гипотеза образования Земли и Луны из крупно-масштабного газо-пылевого
сгущения, размер которого ограничен радиусом Хилла, т.е. составляет приблизительно 1 млн. км.
Сжатие этого супрапланетного газо-пылевого образования приводит к адиабатическому
повышению температуры его внутренних частей, испарению летучих с поверхности частиц, в том
числе железа. На определенном этапе, в пределах периода 50–70 млн. лет с начала возникновения
Солнечной системы, происходит фрагментация супрапланетного газо-пылевого диска, отделение
Луны и образование зародыша Земли. Аккреция оставшейся части газо-пылевого материала
осуществляется преимущественно Землей. В ходе этого процесса газ, представленный первичным
водородом, выжимается из диска. С водородом выносится из межчастичного пространства пар.
Газодинамический лифтинг приводит к утрате летучих, в том числе Rb, Xe, Pb, что находит
отражение в изотопных системах Rb–Sr, Xe–I–Pu, U–Pb. Газо-пылевая аккреция завершается в
период 110–130 млн. лет (наиболее вероятно
120 млн. лет) с начала возникновения Солнечной
системы. С этого момента прекращается газодинамический лифтинг, утрата летучих, и начинается
история Земли как конденсированного тела.
110. Замана Л.В.
ИЗОТОПНЫЙ СОСТАВ ВОДОРОДА И КИСЛОРОДА АЗОТНЫХ ГИДРОТЕРМ БАЙКАЛЬСКОЙ РИФТОВОЙ ЗОНЫ С ПОЗИЦИЙ
ВЗАИМОДЕЙСТВИЯ В СИСТЕМЕ ВОДА–ПОРОДА//
Доклады Академии наук. 2012. Т. 442. № 1. С. 102
111. Скуфьин П.К., Лютоев В.П.
СОСТАВ И СТРУКТУРНЫЕ ОСОБЕННОСТИ МИНЕРАЛОВ РАННЕПРОТЕРОЗОЙСКИХ ОСАДОЧНЫХ ПОРОД ИЗ РАЗРЕЗА
КОЛЬСКОЙ СВЕРХГЛУБОКОЙ СКВАЖИНЫ И ИХ ГОМОЛОГОВ НА ПОВЕРХНОСТИ//
Записки Российского минералогического общества. 2009. № 3. С. 15-32.
Geochemical and structural peculiarities of microcline, quartz and carbonates from arkosic sandstone
of Luchlompolo sedimentary formation (III SF) in Pechenga volcano-sedimentary complex were
compared for their specimens from surface outcrops, from 4.8 km depth core of the Kola super-deep
borehole (SG-3) and from 20-400 m depth of the satellite drill-hole IX. It is shown that rocks occurring
in identical position in cross-section of the III SF series are homologues; they are characterized by
similar composition of rock-forming minerals with closely related spectroscopic peculiarities. But there
are some noticeable differences in spectroscopy data on the level of crystal structure defects between
minerals from near-surface and deep horizons. Increasing degree of the crystal structure defects was
revealed for microclines and dolomites from SG-3; it is connected with different grade of their
metamorphic transformations. Increasing share of Ca positions, together with isomorphic admixture of
Mn-ions in dolomite at deep horizons might be caused by combined influence of the depth
metamorphism and long lasted exposition of rocks to high pressure and temperature. In quartz of
arkosic sandstones decreasing concentration of admixture Al and shifting of its isomorphism in
direction of alkaline varieties accompany the depth of occurrence. As an effect of the depth factor (i. e.
up-to-date PT-conditions of rocks occurrence) there was also considered a tendency of decreasing
natural share of paramagnetic Al-centers in quartz, together with concentration of oxygen vacancies in
it.
112.
Ануфриев Г.С.
ПОТОК И ИЗОТОПНЫЙ СОСТАВ ГЕЛИЯ ДРЕВНЕГО СОЛНЕЧНОГО ВЕТРА//
Космические исследования. 2010. Т. 48. № 1. С. 102-108
Исследован изотопный состав и концентрация изотопов гелия в 9 образцах, отобранных на разных
глубинах колонки грунта Луны-24. Получено, что изотопный состав гелия остается неизменным.
Концентрация гелия испытывает значительные вариации. Превышение и снижение от среднего
значения составляют величины 1.5–2 раза. Полагая, что длина колонки грунта (1.6 метра)
образовалась за счет длительного аккумулирования обломочных лунных пород (реголита), на
основе измерения космогенных изотопов разработан метод определения скорости накопления
реголита и метод определения возраста образцов колонки грунта. Получено, что скорость
накопления реголита непостоянна и по длине колонки меняется в пределах (0.2–0.8 см)/106 лет.
Диапазон времени формирования исследованной части колонки составляет величину 100–600
миллионов лет. Наблюдаемое снижение концентрации (250 и 600 миллионов лет) может быть
связано как с солнечными, так и с лунными процессами. В частности, исследована возможность
диффузионных потерь гелия по механизму скачковой диффузии. Определены параметры
диффузии. Сделано сопоставление временных периодов наблюдаемых вариаций солнечного ветра
с эпохами и периодами палеонтологии.
113. Бучаченко А.Л.
ИЗОТОПНЫЕ ЭФФЕКТЫ РТУТИ В ЭКОЛОГИЧЕСКОЙ ХИМИИ И БИОХИМИИ РТУТЬСОДЕРЖАЩИХ СОЕДИНЕНИЙ//
Успехи химии. 2009. Т. 78. № 4. С. 345-354
Рассмотрены изотопные эффекты ртути в экологически значимых химических и биохимических
реакциях. Открытые недавно аномальные эффекты для магнитных ядер 199Hg и 201Hg доказывают,
что и химические, и биохимические превращения ртутных соединений (вне и внутри живых
организмов) происходят по радикальным спин-селективным механизмам. Обсуждены
закономерности изотопного фракционирования в природных фотохимических процессах и в
тканях живых организмов.