Sedimentary Geology Geos 240 – Chapter 5 The Principles of Stratigraphy Dr. Tark Hamilton Camosun College Correlation of Stratigraphy This mainly works for bedded Sedimentary rocks Correlation of rocks, beds, successions, fossils Lithology: Lithostratigraphy Biostratigraphy: widespread but short lived fossils Chronostratigraphy: zircons, igneous tephra/dyke Allostratigraphy: unconformity bounded packages Sequence Stratigraphy: cycles, eustatic, genetic Absaroka Series Stratigraphy of Northern Ellesmere Island, Nunavut Atlantic Opens Kaskaskia Series Iapetus Closes (Missing Permian) Bayou-Delta Facies Givetian to Fammenian: Tiktaalik Origins of Stratigraphy: Founders I ~1550CE Leonardo da Vinci: Tethyan marine fossils in Italian alps 1669 CE Nicolaus Steno: Original Horizontality, Superposition (younger on top of older beds) ~1750 CE James Hutton: Uniformitarianism (gradualism), Geological cycles (uplift/tilting, erosion. Sedimentation) & Deep Geological Time ~1815 CE William Smith: Principle of Faunal Succession, one of earliest Geological maps, Strata of England and Wales Origins of Stratigraphy: Founders II ~1842 Alcide d’ Orbigny: Biological stages 10 – 100 Ma, evolution based assemblages. Crude biostratigraphy. ~1856 Albert Oppel: Biologic zones = range of a specific organism, higher resolution biostratigraphy. ~1917 Joseph Barrell: Base level or sea level changes will result in breaks (unconformities) genetic strat. 1963 Larry Sloss: Subaerial unconformities bound stratigraphic sequences. Allostratigraphy ~1960’s Harry Wheeler: Time distance diagrams: duration, extent and hiatus in strat. Sequences 1977 Peter Vail: Global Eustatic Sea Level changes & Global correlations on seismic strat. Who needs biostrat, local basins? William “Strata” Smith: 1769-1839 Principal of Stratigraphic Association of Fossils (faunal succession) 1815 1st Geological Map of England Canal Surveyor 1st Wollaston Medalist of the Geological Society of London Cross Section of London Basin Jerome Harrison, 1882 Following in the footsteps of William “Strata” Smith Correlation of Stratigraphy Comparing & connecting stratigraphic successions between localities: trenches, cliffs, boreholes or across and between basins Lithology: Lithostratigraphy, Original Triassic, 3 distinctive beds across the Alps. (Alberti’s Trias referred to the division of these strata into three units: the Bunter [or Buntsandstein], Muschelkalk (Limes), and Keuper (Marls), known as the “Germanic facies,” is mainly Continental. The type sections are now more widespread Marine facies based on ammonoids. Muschelkalk-Keuper Boundary: Winterswijk Netherlands: H.W. Oosterink et al 2006 Marls/Black Clays Rhaetian/Liassic Muschelkalk Limestones (Buntsandstein Unexposed) Correlation of Stratigraphy Biostratigraphy: widespread but short lived fossils Relative ages requires statistical numbers of fossils Only good to +/- 1Ma (the average species lifespan) Chronostratigraphy Absolute radiometric dates from: zircons, apatites, igneous events, tephra-ash beds, U-Pb or 39Ar/40Ar Magnetic Reversal Stratigraphy ≤ Cretaceous Marine Stable Isotope: H/D, 16O/18O, 32S/34S, 12C/13C Allostratigraphy: unconformity bounded packages Sequence Stratigraphy: cycles, eustatic, genetic 1800’s Faunal Succession & Correlation: Stephanoceras and Micraster Lower Jurassic (Midlands) & Upper Cretaceous Chalk Ammonite (Cephalopoda) & Echinoid (Heart Urchin, Echinodermata) Biostratigraphy Dozens to hundreds of species Gradual structural changes evolution Biozones (time), Stages (evolutionary differentiation) Picky species nail the environment, quiet, rough, O2 FAD: First occurrence datum Coincident Range (Concurrent species) LAD: Last Occurrence Datum Biocenose assemblages (living ecologies) Thanatocenose assemblages (enviro-accumulations) Chronostratigraphy Post WWII, Harold Urey, U.Chicago, Solid Source Mass Specs, 238U 206Pb, 87Rb 87Sr & 87Sr/ 86Sr, Deuterium, Precambrian Atmosphere, Nobel Prize Thermochronometry, Derek York U of T : Lunar rocks, Ar-39/40, thermal blocking temperatures Chronostratigraphy: Radio-isotopes U/Pb clocks from Zircon & Baddeleyite for Precambrian sediments, igneous cores & meta rims Rb/Sr for intercalated Volcanics or feldspars for Mesozoic and older rocks (due to long half life and low Rb/Sr ratio) K/Ar for Pliocene and older Volcanics 39/40Ar some sedimentary minerals like Glauconite or Fission Track for Pleistocene and older Volcanics Disequilibrium Uranium series isotopes (Ra for Ca) for Pleistocene & older Carbonates, reefs, speleothems Radioactive fallout correlation dating: 137Cs, 90Sr Allostratigraphy (Larry Sloss, 1963) Major Unconformities bound packages of stratigraphy which correlate across and between continents Caused by tectonic and global eustatic events, 10-100 Ma long for North America: Zuni Absaroka Kaskaskia Tippecanoe Sauk Later Peter Vail of Exxon extended this to the Atlantic Basin mainly on eustatics alone & Seismic Sequence Stratigraphy Stratigraphic Variability for a Hypothetical Lithostratigraphy Relative Datum flattened Shale line to right edge Log Shape Analysis: Wiggle Matching SP or Resistivity 2 Methods of Defining Stratigraphy Ordovician Cambrian Paleocene (Tertiary) Maastrictian (Cretaceous) Cow Head Breccia: Green Point Newfoundland K/T Boundary Clay, Frenchman Valley, Saskatchewa A) Nothing Happened or B) Widespread Distinctive Event Zuni Absaroka Kaskaskia Tippecanoe Sauk Allostratigraphic Breaks in Rift Basin Formations are Lithostratigraphic Subdivision of Regional CambroOrdovician Strata: by Litho & Allostrat. Tippecanoe is Upper Ordovician – Silurian over Sauk = Upper Cambrian – Middle Ordovician Biozones Biozones: Maastrichtian Chalk NW Europe # = Species Concurrent Range Biozones