geOl0gy
t)
of Hidalgo
County ftontinuedfrompage
Tertiary
I
APACHEI.']ILLS
PETERSON.
fl976)
2
PYRAMIDI4TS
DEAL A ELSTON
(submitled)
3
COYOTEHILLS
THORMAN.(1977:
lisqm -irock dot6
b-y C w N A E S E R .
USGS)
27.2!O6
Trls
Trtg
lsmi l+,+) Tcql Trtl
2701o6
Tcd
Tml
Twt
Trc
Tpt
Toqm
:
so.zrtz
f+]+l
I
o
SOUTH- C€NTRAL
SouTliEBN P,q-oNqLLL.
PELCT'IClLLo
MTS
MTS. q NOEN{EEN
E G D€AL
OUADALUPEMTS
(unDlblished)
E.E.ERB
Doleafrom
Ph D dis€€rlolim
MARJANIEt,4I
Univ of New l4exico
(rn preporctrcn)
t969)
Tob
Tdo
Tdc
'Tca
Twp
Tcb
Tcq2
k
A1
SOUTHERN
oENTRAL
ANIMAS MTS.
ANII4ASI'4TS
E E, ERB
E.E.ERB
Ph.D.dissqlotion
Pn.D.dissertohon
Unrv.
of f,l,ef,/Mexico Univ.of I'lewMexico
( in Dr@orotion)
irii oreooiotiont
ZELLERA ALPER(1965) ZELLER(1964
ALAI'4oHUEco MTS.
DE REITER
MSTTIesis
Univ.ol NetMqim
(rn orooorotrm)
+i?lo.8
Tsc
Tbu
Twci
T9L
3.2
3581
Tpr -
Tms
Tgw
-Twc
368ro,8
Tbb
Tom
Tch
Tbl
Twm
3.5 +08
Tmb
Trc
352 I o,8
Ttc
Tbr
rm2
Top
?€4!01
?/
?/ rop
Ter
rbh /
?
Tbm
2 5 . 1t t 2
Tgc
243! A 2
TKs
Tbc
I
EXPLANAT/ON
tz;rrB
ffi
g
O
PRE-TERTIAR/
soMl BASEMENT
BASALTICA ANDESITIC
LAVA FLOAiS
sOKM
INTRUSIVE
ROCKS
?t''',tj1l
LATITICTO RHYO.ITIC
LAVA FI OWS
l;I-^
| ^Y
E^Y!
7l
FELSICASH-FLOWA
AIR-FALL TUFFS
CLASTICROCKS
\
CALDERA-COLLAPSE14EGABRECCI
A
Frcunr 2-ConRELATroNCHARToF CeNozorcrcTg-Gillespie Tuff; Tbaz-basaltic andesite2,
NEOUS
ROCKS
OFHIDALGOCOUNTY.NEWMPXTCO.
Tp-Park Tuff ; Tba,-basaltic andesite.
modified from Deal and others(1978).Symbols
are explainedin stratigraphic order within each Cor,uux S-CBxrner, Axrrvrs Mouxrrrxs. TKtTimberlake fanglomerate; Tad-andesite of
column.
Taylor Draw; Tbc-Bluff
Creek Formation;
Coluur l-Apecnr Hrr,r,s.Chapo Formation, inToc-Oak Creek Tuff; Tam-Animas quartz
rnonzonite; Twm-Walnut Wells monzonite;
cludingTcq,-lower quartzlatite member;TcaTbc-Basin Creek Tuff: Tbb-tuff of Black Bill
andesite member; Tcqz-upper quartz latite
member; Tcb-basalt and andesite member.
Canyon; Tch-Center Peak Andesite; Tgr-tuff
of Gray Ranch; Tg-Cillespie Tuff; Tcp-Center
Taqm-quartz monzonite prophyry; TampPeak Andesite;Tp-Park Tuff; Tpc-Pine Canmonzoniteporphyry; Twp-rhyolite of Wamel's
yon Rhyolite;Tda-Double Adobe Latite; TokPond.
O.K. Bar Conglomerate;
Tab,-alkali basalt3.
Cor,uux 2-Pynemo Mouxrerns. Kas-andesite of
Shakespeare;Kag-andesite of Gore Canyon; Coruul 6-Sournrnx Axnn.rs Mouxrrrrs. TgTlg-granodiorite porphyry stock of Lordsburg
GillespieTuff; Tab,-alkali basalt l; Tp-Park
mining district, Thc-andesite of Holtkamp CanTuff; Tvp,-volcaniclastic and pyroclastic rocks
i--r
yon. Pyramid Mountainsvolcaniccomplex:Tjpl; Tab,-alkali basalt 2; Tpt-rhyolite of
t.
rhyoliteof JosePlacenciaCanyon;Twc-tuff of
Packer's Trail; Tvp,-volcaniclastic and pyrot , ' . ' t l !"r,
'
WoodhaulCanyon;Tgw-tuff of GrahamWell;
i.
clastic rocks 2; Tok-O.K. Bar Conglomerate;
1, "'2.
a.u" n
Tms-andesite of Mansfield Seep;Tuw-latite of
Tab:-alkali basalt3.
,.i
Uhl Well; Tpp-rhyolite of Pyramid Peak.
i'?
1
"2
Tpdm-diorite and monzonitecompositestock; Coruux 7-Sournpnn Pnroxcrrlo rxr Nontxsnx
;,,^ r"ri" 1
Gueorr,upn MouNTArNs.Tgc-tuff of Guadalupe
I
Tai-intrusive andesite. Rimrock Mountain
;
:'"qU
l
Canyon; Tbh-breccia of Hog Canyon; TmbGroup: Trt, through Trtr-tuff members;Trb,
PUOCENE-QIAIERNARY
sedimentarybrecciaand mudflows; Tom-quartz
m
throughTrbr-basaltic-andesite
members.
latiteof OutlawMountain;Tbu-biotite-rich ash*aa a
[l
Coluux
3-Coyorr
Hnrs. VorceNrcs oF
flow tuff, unnamed;Tsc-tuff of SkeletonCanyon; Tcd-rhyolite of Clanton Draw; Tcg-conPorsoox: Tpr-rhyolitic tuffs member; Tpwquartz latite member; Tpl-lithic tuff member;
glomerate,unnamed;Tda-Double AdobeLatite;
F FLUORSPAR
!
U IRAN UM
Tpq-quartz latite lava member;Tpf-clastic tufTab-alkali basalt.
,"----:"
. -*"
TRAVERTNE
T
faceous member. Trc-rhyolite lava of Coyote
Coruur t-Sourn-Cnrrner
Pnlorcrr,lo MouN- Ftcunn 3-LocATIoN oF MINES AND pRospEcrs IN
Peak; Twt-rhyolite welded tuff; Tm,-moonretxs. TKs-conglomerate and sandstone,late
WHICH VEINSARE PRESUMED
TO gS MTOCPXEEXP
stone-bearing
rhyoliteash-flowtuff l.
Cretaceousor early Tertiary; Tbm-tuff of Black
youNGER,rse LrcHtlttNc Docx KGRA, AND ocCor,uux 4-Ar,ruo
Hurco MouxrarNs. TKsMountain; Ter-tuff of EvansRanch;Top-PorTO BE7
CURRENCES
OF BASALTDATEDORPRESUMED
conglomerateand sandstone,late Cretaceousor
phyritic latite of Owl Canyon; Tap-unit of
M.Y.ORYOUNCER.
early Tertiary; Tml-volcaniclastic mudflows and
Antelope Pass;Twci-Weatherby Canyon ignimlakebeds;Tba,-basaltic andesitel: Tbc-Bluff
brite; Tmr-moonstone-bearing rhyolite ashflow
Creek Formation; Tw-tuff of Wood Canyon;
tuff 2, unnamed;Tbr-flow-banded rhyolite,unToc-Oak CreekTuff; Tgr-tuff of Cray Ranch;
named:Ttc-tuff of Trail Creek.
A
Mn
Februaryl9T9
MINE oT PROSPECT
MANGANESE
NewMexicoGeology
gold, silver, and tungsten worth more
than $2 million (Granite Gap, SanSimon,
Kimball districts). Instrusions of midTertiary ageseemto control metaldeposits. Thesedistrictslie on a faulted arch in
which mid-Tertiary volcanicrocks flank
pre-Tertiaryrocks. Possibly the arch is
the deeply eroded resurgentdome of a
cauldron from which the SteinsMountain
and/or Weatherby Canyon tuffs of Gillerman (1958)erupted,but this relationship has not yet beendocumented.In the
GraniteGap district, galenaand oxidized
lead-silverores replace Paleozoic limestone near quartz monzonite porphyry
dikesof mid-Tertiaryage(30 to 3l m.y.)
and tungsten-bearingskarns are associated with a 32 m.y. granite (datesfrom
Hoggatt and others, 1977\.ln the west
part of the San Simon district, skarn depositsshow a zonal patternaround a major northwest-trending
fault, the Johnny
Bull fault of Gillerman (1958).Near the
fault, copper mineralization predominates (Johnny Bull mine), away from the
fault there are zonesof zinc-lead (Silver
Hill mine) and lead-silver(Elston, 1963;
Cartenand others, 1974).The skarnsare
localizedin Paleozoiclimestonenext to
small felsitedikesrelatedto larger bodies
of quartz monzoniteporphyry (30 to 3l
m.y.). The zoningpatternsuggests
a magma sourceat depth in the vicinity of the
JohnnyBull fault. On the eastsideof the
district,lead-zincskarnhasbeenminedin
the CarbonateHill minenext to an altered
monzonite body. South of SteinsPass,
quartz monzonite porphyry is intensely
alteredand pyritized; surroundingandesite is alteredand mineralizedwith silverbearing galena veins near rhyolite intrusions(Mineral Mountain mine). North of
SteinsPass,in the Kimball district, gold
and silver, respectively,have beenmined
from veins in the Beck and Volcano
mines. Both mines are controlled by
elongateddomesof flow-bandedrhyolite,
possiblyring-fracturedomesof a source
cauldronof the WeatherbyCanyon-Steins
Mountain tuffs.
The recognition of many porphyry
bodies as rnid-Tertiary rather than
Laramide, and as related to cauldrons,
has been an important result of current
work. In Hidalgo County, the cumulative
productionof metalsassociated
with midTertiary cauldronsand intrusions is insignificant, even when compared to the
modest production from depositsassociated with local Laramide porphyry
bodies.It remainsto be seenwhetherour
growingknowledgeof cauldronswill lead
to new discoveriesof ore deposits or
whether the mid-Tertiary igneousrocks
4
February 1979
NewMexicoGeology
nrewlnrzw
R2owIRrsw
:5t
f,,tat1tr
trJ
J'
Jl
/
"'1
1n
I
6\t
(t,
:
\
Tzls_
T255
Ire+s
lTzss
\
I
o'
e/
.s/
I
I
a
o
\ |I
-sl
EI
I
bl
FI
i\
I
r*
\l
T25S
| <.r
\-
l
rzGS
T25S
Irzss
PYRAMID
MOUNTAINS
"";'^;,
E t:n0,";r'go'l3;[,\
y
O
"I
-Y/
/ ,/
,/
ji"i""#''b -.ffi oB?'iiJ$sjE,,
betweenAnimosvottey ..- t::.rff
ISH|
"?^$filn;lt?31:'""'.fh
R2OW|R|9W o
?HrLEs
)/
-- _-*__ /
R r s w l rR8 w
nrewlnrzw
zKH
ANDTgs Lrcnrnrnc Docx KCRA.
nrcune4-TecroNrc sKETcH
MApor rHE Murn cAULDRoN
are inherentlylessfavorablefor explora- the same township, layers of banded
tion than Laramideigneousrocks (Elston travertine with local manganeseoxide
and others,1976a;Elston, 1978).
mineralizationappearin outflow sheetsof
On the eastern side of the Animas the Bluff CreekFormation.
Valley, young faults belonging to the
Basin and Range episodecontrol lowGeothermalpotential
temperaturevein depositsof psilomelane
(CaprockMountain and Animasdistricts)
Hot or warm water has beenreported
and of fluorspar(Lordsburgand Animas from wells in the San Simon, Animas,
districts).At the Cliffroy mine (Caprock Lordsburg,and PlayasValleys.The chief
Mountain district) and the Doubtful or geothermalprospectis on the McCants
Animas mine (Animas district) some of farm in the Animas Valley, whereboiling
theseveinsgradeinto near-surfacedepo- water and hot rhyolite were encountered
sits of travertineor bandedcalciteand are at26.5m (87 ft) in a well drilled in 1948in
closelyrelated to former hot springs(fig. NE% sec.7, T. 25 S., R. 19 W. (Kintz3). In the Dog Mountains,uranium show- inger, 1956).The area is now part of the
ings in chalcedony-opal
veinsin ash-flow Lightning Dock Known GeothermalRetuff outflow sheets are controlled by sourcesArea (KGRA). It is the only
faults(SE%sec.15,T. 34 S., R. 15 W.). known placein southwestern
New Mexico
In and around the northeasternpart of in which indicated subsurfacetempera-
Petroleumpotential
part
The
of Hidalgo County north of
rEXAS
NEW T,IEX/CO
Lordsburg lies on the southern flank of
ffi VEo'].l'^frJ'48[*'
the Burro uplift (Elston, 1958)and is not
I,,4OGOLLON
l)
ti[rbhKIu"
,-''i0l5fr',
likely to have petroleumpotential. The
/o SEOIMENTARY
southern part of Hidalgo County lies
f / eastl
Basin
within the late PaleozoicPedregosa
OROGRANDE
basin. The
Cretaceous
Lower
and
a
BASIN
PedregosaBasin has many similarities
with the highly productivePermian Basin
of southeasternNew Mexico and west
Texas.Greenwoodand others(1977)gave
an optimistic appraisalof its petroleum
potential. Thompson and others (1978)
havesummarizeddrilling results.
The discovery of numerous ash-flow
ENLARGEMENO
T F
-i
and other volcanic centersin
cauldrons
souruenruHtoai-co
xas(,
the PedregosaBasin should introduce a
it( \
-.6on&trtn\,""*
note of caution. Elsewhere,in the San
Juan Mountains of Colorado and the
r o oM l
0
Mogollon Plateau of New Mexico,
Ftcuns S-MeJoR sEDIMENTARy
BAsrNs
oF sourHERNNEw Mnxrco eNDsuRRouNDtNG
REcroNs,from Greenhave been interwood and others(1977),and outcrop areasof mid-Tertiary volcanicrocks. The outline of the Pedregosa clusters of cauldrons
of major
Basin is drawn on the 2,000-ft isopach for Pennsylvanianrocks. The inset showsdetails for southern pretedasthe surfaceexpressions
(Steven
1976;
Lipman,
and
Hidalgo County; numbersof cauldronsarethe sameas for fig. l.
batholiths
Elston and others,1976b).The clustering
tures exceed300" F (Rennerand others, exposedfurther south,at TabletopMoun- of cauldrons in the Animas, southern
1975;Smith,1978).
tain. All postulatedoccurrencesof sup- Peloncillo,and Pyramid MountainssugThe hot wells of the Lightning Dock posedly Pliocene or younger rhyolitic geststhe sameinterpretation for parts of
KGRA seemto be structurallycontrolled rocksin southwestern
New Mexico(Flege, the PedregosaBasin (fig. 5). The KCM
by the intersectionof the ring-fracture 1959;Ballman, 1960;Elston, 1965b)have No. 1 Forest Federalwildcat, drilled on
zone of the Muir cauldron and a recently now been found to be Oligocene.Also, the Winkler anticlinein sec.3, T. 3l S.,
active fault on the eastsideof the Animas widespreadhydrothermalalteration in the R. 18 W. (fig. 1), in fact, encountered
Valley (Deal and Elston, submitted; PyramidMountains,eastof the hot wells, quaftz monzonitebelow 1,254m (4,113
Smith, 1978).The OligoceneMuir caul- is now attributed to activity of the ft). The quartzmonzoniteappearsto be a
dron is not suggestedas a modern heat OligoceneMuir cauldron,not the modern ring-fracture intrusion of the Juniper
source.Rather, the broken ground of its geothermalsystem;most of it is older cauldron and the Winkler anticline was
ring-fracture zone could have provided than the tuff of GrahamWeU(fig. 2, col- probablydomedasa resultof its emplaceconduitsfor thermalwaters(fig. 4). If the umn 2). On the other hand, severalsites ment(Elstonand Erb, 1977).
part of Hidalgo
Only the southeastern
Weatherby Canyon and SteinsMountain of basalticactivity younger than 7 m.y.
Tuffs came from a sourcein the Pelon- havenow beenfound (fig. 3). A combina- County is not known to have major volcillo Mountains,the ring-fracturezoneof tion of deep-seated
basalticactivity, ex- canic centers.There, the Little Hatchet
pass
that cauldroncould also
throughthe tensionalfaulting, and deeplyconvecting Mountains are intruded by monzonitic
LightningDock KGRA.
meteoric water could account for the and granitic stocksof unknown age.The
Big Hatchet Mountainsand parts of the
The widespreadoccurrenceof Miocene observedgeothermalsystem.
In conclusion, a volcanogenichigh- Sierra Rica are free of known intrusions
or younger low-temperaturefluorite and
psilomelaneveins and relatedhot-spring temperature,vapor-dominatedgeother- other than minor dikes. The Alamo
that the hot wells mal systemprobablyis not presentin the Hueco Mountains are coveredwith ashdeposits(fig. 3) suggests
of the Lightning Dock KGRA may be the Lightning Dock KGRA or elsewherein flow tuff outflow sheetsbut showno sign
relict of a geothermal system that once Hidalgo County. If sufficient hot water of major non-basalticvolcaniccenters.
The limits of the shallow Plutons
was much more widespread.Specifically, and steam are present in the Lightning
the largest known fluorite-calcitevein set Dock KGRA, they could be applied to postulatedas lying beneathcauldronsare
in Hidalgo County is at the foot of Light- local agriculturaluses,for dryingcropsor unknown and so is the extent of thermal
Whetherthe supply and hydrothermal effects. In the central
ning Dock Mountain, near the Doubtful heatinggreenhouses.
(Animas)minein sec.15,T. 25 S., R. 19 of hot water is sufficient to do so on a part of the PeloncilloMountains,wherea
W. Some vein zones are 60 m (197 ft) large scaledependson local hydrologic cauldronis possiblebut has not yet been
wide. They are separatedfrom the flu- conditions,especiallyon how much hot demonstratedand where mid-Tertiary inorine-bearinghot wellsby about 5 km (3 water circulated from deepbedrock frac- trusions are pervasive, Precambrian
mi) of valleyfill without outcrops.
tures into shallow cold-water aquifers graniteyieldeda 34 m.y. K-Ar age.This
The ultimate heat sourcefor the Light- within the late Cenozoicvalley fill. This is suggestsargon loss becauseof mid-Terning Dock KGRA is uncertain.The rhyo- unknownat present.The hydrologiccon- tiary heating(Hoggattand others, 1977).
lite brecciaor conglomeratepenetratedby ditions that prevail in the Lightning Dock Evidenceof widespreadlate Tertiary hotthe hot wells is not likely to be modern. KGRA may well be repeatedelsewherein spring and hydrothermal activity, mainly
More likely, it is early Mioceneconsoli- the Animas, Playas, San Simon, and in the Animas Valley and controlled by
Basin and Range faults, places another
dated valley fill. Material of this type is LordsburgValleys.
to2'w
35'N
Februaryl9?9
I
NewMexlcoGeologY
5
constrainton petroleumpossibilities.On dateswere determinedby P. E. Damon and M. Hoggatt, W. C., Silberman,M. L., and Todd, V.
R., 1977,K-Ar agesof intrusiverocksof the Centhe other hand, in the KCM well, severe Shafiqullah, University of Arizona, unless attral PeloncilloMountains,Hidalgo County, New
thermaleffectswerelimited to about 700 tributedto othersources.
Mexico:Isochron/West,no. 19,p. 3-6
References
cited
m (2,296ft) from the igneouscontact.At
Kintzinger,P. R., 1956,Geothermalsurveyof hot
greaterdistances,Pennsylvanian-Permian Ballmann,D. L., 1960,Geologyof the Knight Peak
groundwater near Lordsburg, New Mexico:
area, Grant County, New Mexico: New Mexico
Science,
v. 124,no.3223,p.629-630
marine sedimentaryrocks retainedsome
Bureauof Minesand MineralResources,
Bull. 70, Marjaniemi, D. K., 1969,Geologichistory of an
of their petroleumsource-rockcharacter3 9p .
ash-flow sequenceand its sourceareain the Basin
istics (Thompson, 1977). The Humble Carten,
and Range province of southeasternArizona:
R. 8., Silberman,M. L., Armstrong,A. K.,
No. I StateBA well, drilled to a depthof
Ph.D. thesis,Universityof Arizona, 176p.
and Elston, W. 8., 1974,Geology,trace-metal
5,190m (17,023ft) in NE% sec.25, T. 32
anomalies,and base-metalmineralization in the Peterson,S. L., 1976,Ceologyof the ApacheNo. 2
mining district, Hidalgo County, New Mexico:
central Peloncillo Mountains, Hidalgo County,
S., R. l6 W., off the northwestsideof the
M.S. thesis,Universityof New Mexico,86p.
New Mexico (abs.): New Mexico Geological
Alamo Hueco Mountains,encountereda
Renner,J. L., White, D. 8., and Williams,D. L.,
Society,Guidebook26th field conference,p. 378
show of gas in Epitaph Dolomite (Per- Deal, E. G. and Elston, W. 8., in preparation, l9'15, Hydrothermal convection systems, in
mian) and a show of oil in El Paso
Assessment
Geologyof the LightningDock KGRA and vicinof geothermalresources
of the United
ity, Pyramid Mountains and Animas Valley,
States-1975: U.S. GeologicalSurvey,Circ. 726,
Limestone (Ordovician); no thermal
p. 5-57
Hidalgo County, New Mexico: U.S. Geological
metamorphismwasreported(Greenwood
Smith, Christian, 1978,Ceophysics,geology,and
Survey,Open-fileRept.,49p.
and others, 1977). Evidently, mid- Deal,E. G., Elston,W. E., Erb, E. 8., Peterson,S.
geothermalleasingstatus of the Lightning Dock
Tertiary thermal gradientswere high in
Known Geothermal Resources Area, Animas
L., Reiter,D. E., Damon,P. E., and Shafiqullah,
Hidalgo County. Areas of destructively M., 1978,Cenozoicvolcanicgeologyof the Basin
Valley, New Mexico: New Mexico Geological
and Rangeprovincein Hidalgo County, southSociety, Guidebook 29th field conference, p.
high temperaturesmay havebeenlimited
western New Mexico: New Mexico Geological
343-348
to the immediatevicinity of cauldrons.
Society, Guidebook 29th field conference, p. Smith,R. L., 1960,Ash flows:GeologicalSocietyof
More distant areasmay have beenunaf2r9-229
America,Bull.,v.71, no.6, p.795-842
fectedor may evenhave had their petro- Elston,W. 8., 1958,Burro uplift, northeastern
limit Smith, R. L., and Bailey, R. A., 1968,Resurgent
of sedimentarybasinof southwesternNew Mexico
cauldrons:GeologicalSocietyof America,Mem.
leum possibilitiesenhanced.Under favorand southeasternArizona: American Association
116,p.613-662
able circumstances,moderate heating
of Petroleum Geologists, Bull., v. 42, p. Stevens,
T. A., and Lipman, P. W., 1976,Calderas
may provide energyfor generation,mat2513-r527
of the SanJuanvolcanicfield. southwestern
Coluration, and migrationof hydrocarbons. Elston,W. 8., 1963,Geologyand mineralresources orado:U.S. GeologicalSurvey,Prof. Paper958,
of Hidalgo County, New Mexico: New Mexico
Bureauof Mines and Mineral Resources,
Openfile Rept.,781p.
1965a,Mining districtsof Hidalgo County,
New Mexico: New Mexico GeologicalSociety,
Guidebook16thfield conference,p. 210-214
1965b,Volcanicrocks of the Mimbresand
Upper Gila drainages,New Mexico: New Mexico
Geological Society, Guidebook l6th field conference,p. 16'1-179
1978,Mid-Tertiary cauldronsand their relationshipto mineralresources,
southwestern
New
Mexico: A brief review: New Mexico Geological
Society,
Spec.Pub.7,p. 107-l13
Elston, W. E., and Erb, E. 8., 19'17,Cenozoic
volcano-tectonicsettingof the KCM No. I Forest
Federalwell, AnimasMountains,Hidalgo County, New Mexico: New Mexico Bureau of Mines
and MineralResources,
Circ. 152,p.53-62
Elston,W. E., Rhodes,R. C., and Erb, E. E.,
1976a,Control of mineralizationby mid-Tertiary
volcaniccenters,southwestern
New Mexico:New
Mexico GeologicalSociety, Spec. Pub. 5, p.
125-130
Elston,W. E., Rhodes,R. C., Coney,P. J., and
Deal, E. G., 1976b, Progressreport on the
Mogollon Plateau volcanic field, southwestern
New Mexico, No. 3-surface expressionof
pluton: New Mexico Geological Society, Spec.
Pub.5, p. 3-28
Flege, R. F., Jr., 1959, Geology of Lordsburg
quadrangle,Hidalgo County, New Mexico: New
Mexico Bureau of Mines and Mineral Resources,
Bull. 62, 36p.
Gillerman, E. G., 1958, Geology of the central
Peloncillo Mountains, Hidalgo County, New
Mexico and CochiseCounty, Arizona: New Mexico Bureauof Minesand MineralResources,
Bull.
gratefully acknowledge
Acxrow-Eocrcrrs-We
57,152p.
support from the New Mexico Bureauof Mines and Greenwood, Eugene, Kottlowski, F. E., and
Mineral Resources,New Mexico Energy Resources
Thompson,Sam III, 1977,Petroleirmpotential
Board grants 75-109,75-117,76-2&,76-350, and
and stratigraphyof PedregosaBasin:Comparison
77-3104,U.S. GeologicalSurvey grants 14-008with Permian and Orogrande Basins: American
001-G-255 and 14-08-001-c-348and National
Associationof PetroleumGeologists,
Bull., v. 61,
Science Foundation grant EAR 77-24501. K-Ar
p. 1448-1469
Discussion
This project is still in progress,
therefore this report is preliminary. Final
interpretationsmust await the completion
of mapping, petrographic work, and
chemical analyses.The reader may be
skepticalabout the proliferation of ashflow tuff cauldronsand of interpretations
that hingeon cauldrons.The recognition
that virtually all regional ash-flow tuff
sheetshavetheir sourcesin collapsedcentral volcanoeshas come slowly sincethe
publicationof Smith (1960).Criteria for
recognizingthesecentral volcanoeshave
alsobeenaccumulatingslowly;Smith and
Bailey(1968)remainsthe bestsummary.
The stratigraphicframeworkforms the
basisof our interpretations.Complicated
as our interpretationsare, they still represent a simplificationof reality. Many of
the regionalash-flowtuff sheetsshownon
fig. 2 are without known sources,so that
the number of cauldronsis likely to increaseas work progresses.
We regardthe
cauldronsas keys to understandingmidTertiary events,geologicstructures,and
mineralresources.
They are the most prominent geologic features in Hidalgo
County.
Februaryl9T9
NewMexicoGeology
3 5p .
Thompson,SamIII, ed,.,197'1,Geology,petroleum
sourcerocks, and thermalmetamorphismin KCM
No. I ForestFederalwell, Hidalgo County, New
Mexico: New Mexico Bureau of Mines and
MineralResources,
Circ. 152,62p.
Thompson,SamIII, Tovar, R. J. C., and Conley,J.
N., 1978,Oil and gasexplorationin the Pedregosa
Basin: New Mexico Geological Society, Guidebook 29th field conference
, p. 331-342
Thorman,C. H., 1977, GeologicMap of partsof the
CoyotePeakand brockmanquadrangles,Hidalgo
and Grant Counties,New Mexico: U.S. Geological Survey, Misc. Field Studies Map MF-924,
L:24,ffi
geologic
Zeller, R. A., Jr., 1962,Reconnaissance
map of southernAnimasMountains:New Mexico
Bureau of Mines and Mineral Resources,Geol.
Map 17
Zeller,R. A., Jr., andAlpher,A. M., 1965,Geology
of the Walnut Wells quadrangle,Hidalgo County,
New Mexico: New Mexico Bureau of Mines and
MineralResources,
Bull. 84, 105p.
I