Garbonatitedikes of the Chupadera Mountains, SocorroGounty, New Mexico byBruce R. VanAllen and David L. Emmons,Tenneco Minerals Company, P.0. Box 27F, Lakewood, C0 80227 and TheodoreP. Paster, Consulting Geologist, 11425 E. Cimmanon Dr., Englewood, C080111
Introduction Bureauof Mines and Mineral Resourcesin- depths of t2-15 km, and metamorphosed at Calcitic carbonatites and thorium-bearing dependentlyidentified the carbonatites(Kent, temperaturesof 500-550"C.The exposed quartz deposits have been identified in the 1.982;Mclemore, 1983). stratigraphic thickness of metasedimentary southern Chupadera Mountains in Socorro rocks may exceed 3,000 ft. Schistosity ap- Counfy.The dikes and quartz veins arehosted profmates original bedding and is indica. by Precambrianmetamorphic rocks, whereas Geologic setting tive of two or more periods of folding before jasperoidoccurs in Paleozoiccarbonate rocks. The Chupadera Mountains are within a carbonatiteemplacement. There aPPearsto The depositsoccur in protractedsections 20, north-trending, west-tilted horst along the be at least one early west-northwest-trend- 21,28, and29,T5S, R1W on the northeastern western margin of the Rio Grande rift. Car- ing episode of isoclinal folding followed by portion of the Pedro Armendaris Spanish bonatitescrop out in a 2 mi'exposure of Pre- a'period of northeast-trendingopen folding Land Grant No. 34 and on the western edge cambrian rocks (Fig. 2), which has been (Bowring et al., 1983). of the Bosque del Apache National Wildlife mappedand describedby Kottlowski (1960), Narrow bodies of biotite schist and am- Refuge.The approimate location of these Condie and Budding (1979), Kent (1982), phibolite within the metasedimentary units depositsand the locationsand agesof other Bowring et al. (1983),and now by the au- are probably metabasalt flows and intru- carbonatitesin the region are shown in Fig. thors of this paper. The Precambrian host sives.Minor dikes of gneissicpegmatite and 1 and Table 1..The carbonatite dikes in the rocks are primarily interfingering quartzo- aplite are also present. Local porphyritic Chupaderaswere discoveredduring a con- feldspathicschist and gneiss,mica schist,and feldspathic schist may be metamorphosed tract uranium exploration program by United minor quartzite. These steeply dipping felsic plutons and perhaps volcanic flows. GeophysicalColporation in 1954(Reim, 1955). metamorphic rocks probably were inter- The youngest Precambrianmetamorphic rock At that time the intrusives were describedas bedded argillaceousand arenaceoussedi- is probably the foliated megacrystic granite "radioactive-calciteveins. " The "veins" were ments with locally abundant felsic, in the southern portion of the Precambrian recognized as carbonatite dikes in 7978 by volcaniclasticdetritus. Condie and Budding exposure.Based on zircon U-Pb isotopicdata, Tennecogeologists during a mineral recon- (1979)suggested that the rocks were depos- this metamorphosedgranite is 1,659 -+ 3 m.y. naissanceprogram. In 1980,the New Mexico ited during continental rifting, buried to old (Bowring et al., 1983).Carbonatite is the
TABLE l-Ages of carbonatites and selected al- kalic rocks in New Medco and Colorado. See Fig. I for approximate geographic locations. Alsoin this issue Paleoenvironmentsof the Ate SouthHospah coal deposits p. 30 Locality (m.y.) Reference Gabaldonbadlands p. 34 1. Chupadera Mountains ? This paper gas p. carbonatite Oil and discoverywells 36, 2. Lemitar Mountains M9 Mclemore, 1982 Service/News p.41- carbonatite MineralSymposium abstracts p.42 3. Monte Largo Hills ? Loring and carbonatite Armstrong, 1980 Staffnotes p. 44 4. Lobo Hill <604 Loring and syenite and Armstrong, 1980; carbonatite Mclemore, 1984 Gomingsoon Albuqucrque '^4 5. PedernalHills <496 Loring and Reinlerpretationof a Precambrian syenite Armstrong, 1980 5. Caballo Mountains ? Staatz et al , 1965 angularunconformity, Manzano Mts. ChupoderoMls. syenite Cretaceousstratigraphy and bio- 7. Florida Mountains 418-750 Brookins, 1974 quartz syenite New Mexico stratigraphy,Clayton Lake State 8, Powderhorn dishict 543-731 Olson et a1.,7977 Park carbonatitesand Pennsylvanianpalynological analyses associatedalkalic rock of severalcoal beds, Santa Fe Co. 9. Wet Mountains 427-560 Olson et a1.,1977; RustlerFormation at the WIPPsite district Armbrustmacher FIGURE l-Location of carbonatites and selected carbonatitesand and Hedge, LateCenozoic Palomas Formation of alkalic rocks in New Mexico and Colorado and associatedalka.lic 7982 south-centralNew Mexico rock schematic location of the Rio Grande rift. See Table 1 for locality names and ages. youngest pre-Tertiary intrusive rock and is Carbonatites phyritic. Many of the intrusives are micro- not metamorphosed. The carbonatites occur as a northeasterly breccias, with rounded and irregular A thin wedge of Paleozoiclimestone and trending, arcuate swarm of steeply dippin! carbonatite fragments set in a carbonatite arkose unconformably overlies the southern dikes that cut the foliation of the Precam- matrix with similar composition. Pheno- margin of the Precambrianrocks. These sed- brian rocks. The dikes typically are exposed crysts, carbonatite fragments, and wall-rock imentary rocks contain no carbonatite dikes within a thin, laterally extensive colluvium inclusions generally align to form flow band- and are presumed to be younger. Poor ex- as rows of boulders. Wall-rock contacts are ing and localflowage segregation.Many dikes posures and major jasperoid zones make rarely observed (Fig. 3). The intrusives are are uniform in texfure, but some have vari- identification of the Paleozoicformations un- in long, narrow zones which, in some ex- able texture along strike. Wider portions of certain. However, Kottlowski (1950)and Eg- posures,contain up to three closelyspaced, others possibly are compositeintrusives with gleston (1982)have documented the CaloJo adjacentdikes. Individual dikes commonly sharp contactsbetween different phasesthat (Mississippian) and Sandia (Pennsylvanian) ar60.2-q.9 ft thick. Selectdikes have been are distinguished by textural contrast. Formations in the map area. traced continuously in outcrop for up to 200 The carbonatites are moderate brown on To the north and eastthe Precambrianrocks ft along strike. Four dike zonesexceed 1,000 fresh surfaces and yellowish brown to red- are covered by a thick Cenozoic section of ft in shike length and may exceed5,000 ft dish brown where weathered. Xenoliths and ash-flow tuff, felsicvolcanic flows, basalt,and with only minor lateral offset by faults. The phenocrystsof magnetite, apatite,and bio- sedimentary rocks, which compose most of extent of carbonatitesconcealed by Paleozoic the ChupaderaMountains (Eggleston,1982). and younger rocks is unknown. To the west the Precambrianrocks are down- Carbonatite textures range from fine to thrown by the Chupadera fault. coarsegrained and from equigranular to por-
ExPlo I Alluvium I Gronile 5onlo Fe cenozoic .9 Porphyriticschist broup ,: terlroryvotcontc ; Amphiboliteond schist Ouorlzo{eldspothic Josperoid f schisl ond gneiss PoleozoicIimestone I lVico schist L Corbonolite dikes
FIGURE 3-Outcrop of a 2.4-ft-thick carbonatite dike. Wall-rock coniacts are concealed by collu- vlum. New AAex[c@ GEOLOGY
o . Soienceand Seruice Volume 8, No. 2, May 1946
Editor:Deborah A Shaw Published quarterly by New Mexico Bureau of Mines and Mineral Resources a division of New Mqio lnstitute of Mining & Tchrology BOARD OF REGENTS Ex Officio Toney Anaya, Gooernorof Nru Mexico Alan Morgan, Superintendentol Publiclnstruclion ADDointed SteveTorres, PieZ , t967-1997, Socorro \ "on,o., Judy Floyd, SeclTreas , 1977-7987,Ins Cruces Cilbert L Cano, 1985-1997,Albuquerque Lenton Malry, 1985-1989,Albuquerque Donald W Morris, 1983-1989,Ips Alamos : side; dotted New Mexico Institute of Mining & Technology if buried Ptridffit LaurenceH Lattman New Mexico Bureau of Mines & Mineral Resources strike ond dip Director Frank E Kottlowski Acting DeputyDirector JamesM Robertson Subscriptions:Issued quarterly, February, May, August, November; subsqiption price $6 O0/calendaryear foliotion Edttotiolmattq: Articles submitted for oublication should be in the editor'shands a minimum of five 15)months before date of publication (February, May, August, o! Novenber) and should be no longer than 20 typewrit- ten, double-spacedpages. All scientific pape$ will be reviewedby at least two people in the appropriate field Scole of study Address inquiries to Deborah A Shaw, Editor o 05 ot Nru MexicoGeology, New Mexico Bureau of Mines & Mineral Resources,Socorro, NM 87801 o I,OOO 2,OOOf t Published.as publicdomain, therelore reproducible without per fr5sion. Sourcecredit rcquested Circuletion:1 ,600 FlgUlE 2-Gene:alized geologicmap_ofcarbonatites in the Chupadera Mountains (precambrian rocks Prinler University of New Mexico Printing Plant atter Kent, 1982;Tertiary rocks after Eggleston, I98Z; and mapping by the authors of this paper).
May 1986 Nm Mexico Geology tite characteristicallystand in positive relief feldspar commonly b from weathered carbonate matrix. Angular morphology and occa wall-rock xenoliths in the dikes are up to 0.7 polysynthetic plagiocle ft long and commonly have reddish rims be- apparentfrom oriented causeof hemat2ation. clear carbonateaggrei Minerarogy ;ffit,4'**".106'" The carbonatitesare composedof calcite eral^. Some samples contain partly nium oxides. with trace to moderate amounts of other recrystallized, fine-grained carbonate mo- Geochemistry minerals commonly found in carbonatites saicJ, making clouiy and originally clear (Table2). A semiquantitative x-ray diffraction grains indistiiguisha'ble. Geochemistry, like mineralogy, is highly analysisof sample 45h indicates 55-657acal- Carbonatite breccia clte,12-15Vo dolomite, 8-10% apatite, 5-10Vo granular,anhedral, cle kaolinite(?), 3-5Voquartz, and trace chlorite. altered biotite, magne Somecarbonatite slabs reveal a swelling clay, con. These minerals ; perhaps montmorillonite, as possiblepseu- phenocrysts.Most cart domorphs after feldspar phenocrystsor in- phenocrysts are rour clusions. causeofabrasion and 1 Two primary carbonate textures are rec- tite commonly contains ognized in thin section (Figs. 4 and 5). occasionally-iscompletely replaced by la- siumcontent,andlowtoaverage_magnesium G-roundmasscarbonate (<0.05mm) appears mellar intergrowths'of qiarti, sparry car- content, They contain elevated concentra- cloudy becauseof abundant fine-giained in- bonate,iron ind titani.r- o*ides, and chiorite. tions of silica relative to a "typical" carbon- clusionsof iron and titanium oxid6s.Coarse- Theseplaty aggregatesof alterationminerals atite, mostly becauseof biotite phenocrysts, grainedcarbonate (0.05-3.0 mm) is clearand rur,g" irp to ii-1" length. Magnetite crys- biotite alteratio-nproducts, and lithic inclu- minerals. The carbona- [rpically occurs as replacementsof feldspar tals"varj, from less than"0.05 to-5 mm in di- sions rich in silicate ina Ui
45h 31 JJ t7 <1 J/t 2 3 <1 47 46b 18 47 t4 ND ND 74 <1 I 1 1 3 47b 52 74 6 t.) /)z I ND ND 4l 5r 47 18 I4 6 481 2 ND ND 40 .A 53c JL 8 72 595 2 2 1 44
FIGURES-Photomicrograph in plane-polarized light of porphyritic carbon- FIGURE4-Photomicrograph in plane-polarized light of partly recrystallized atite with partly resorbed crystals of magnetite (M), biotite (B), and apatite matrix carbonate,trace apatite (A), and sparry calciteafter feldspar (F), after (A). Also cbntains calcite pseudomorphs after plagioclase(P) and lithic frag- lithic fragments (L), and in minor veinlets ments (L).
NetuMexico Geology May 7986 richment of uranium, thorium, yttrium, and TABLE 3-Whole-rock geochemistry in percent. Assays were done by commercial laboratories. + Stan- +* rare-earthelements, which is diagnostic of dard whole-rock geochemistry. $ After Gold, 1966. f Quantitative x-ray fluorescence. Total iron carbonatites (Table 4). gamma-ray F"rO" A spec- "rp."rt"d "t trometer survey has established that radio- Samples from the Chupadera Mountains "Typical" activity is extremely variable along dike Oxide 45h* 45h' 47b' carbonatites outcrops and that uranium and thorium gen- erally are unassociated.Dikes in southwest- sio, I0.27o 7.77o 8.9% 73.07o 5.67Vo ern outcrops commonly have the greatest CO, JI. I 32.76 concentrations of most trace elements. Tio, 0.91 1.11 7.73 3.65 0.50 Al203 1.31 1.9 1.9 4.r 7.77 Linear correlation coefficients(r) better de- Fe2O3*' 4.64 5.48 9.77 r4.85 8.00 fine the interassociation of minor elements MnO 0.89 0.82 0.45 0.81 0-78 (Table5). Basedon student t tests, r values Mgo 3.42 3.70 3.55 7.00 6.10 with a variance of 0.34 from zero are indic- CaO 43.3 43.49 43-97 35.28 37.06 ative of significant positive or negative cor- Na2O 0.046 <0.01 <0.03 <0.03 1.09 relation with greaterthan 95%confidence for KO 0.070 0.07 0.25 0.19 0.81 all element pairs except for those containing PrOt 3.51 2.27 3.78 2.73 7.73 thorium or rubidium analyses.The five r val- Total 99.47o 95.737o ues greaterthan +0.6 may indicate strong positive correlation.Cerium and lanthanum TABLE 4-Abundance of minor and hea'"y elements in representative samples. Values are in ppm * are the most correlative(r : 0.87).The sum unless otherwise noted. Assays were done by commercial laboratories. Arithmetic mean and range of cerium and lanthanum correlateswell with based on 43 semiquantitative XRF analyses and 39 quantitative assays for F, Cu, Zn, Pb, and U. Values zirconium, which suggests that these rare- below detection limits were considered to be 0 for ialculation of the mean. t Weighted average of 200 earth elementsoccur predominantly in zir- analyses from 55 localities (Gold, 1966). $ Total rare-earth-element oxides. con and probably not in apatite or in a dis- Samples from the Chupadera Mountains* tinct rare-earth-elementmineral. Rare-earth "Typical" carbonatiter elements can substitute for a portion of the Element Mean Range weighted average zirconium in zircon when there is partial re- placement of silicon by phosphorus (Berry F 1 ))'l 350-1,800 3,800 and Mason, 1959).The rare-earthelements Ti 1,818 660-3,900 2,998 Mn 2,M9 1,000-4,100 6,040 perhapswere containedoriginally in calzir- Fe 3.76Vo 0.46-8.50Vo 5.61,% tite or zirkelite. Ni 155 20-490 JZ Certain carbonatites from other localities Cu 4l 12-80 88 in the region do not display this association. Zn 772 26-577 160 For example, carbonatitesof the Wet Moun- Rb 62 <10-250 52 tains have discreterare-earth-element min- Sr 720 220-2,600 7,526 eralsand display no correlationbetween Zr I 247 46-700 114 and Ce * La. As calculatedfrom geochem- Zr 1,011 790-7,700 467 ical data of Armbrustmacher and Brownfield Nb 384 110-650 (1978),magmatic carbonatites from the Nb+Ta 560 Wet Ba 1 )7) <30-13,000 4,030 Mountains have a Zr to Ce * La correlation -0.06, Ce 737 <80-4,900 coefficientof whereasthe r value for La 296 <80-1,700 "replacementcarbonatites" is - 0.05. REOS 5,900 Uranium is associatedwith yttrium in car- Pb 56 24-208 27 bonatite samplesfrom the Chupadera Th 197 <20-7,700 694 Mountains, but no discrete uranium or ytt- U 50 3-1,094 57 rium minerals have been identified. An au- toradiograph of 45h, the sample with the at least once before final emplacement. The tains are distal to possible alkalic intrusives. greatesturanium content, reveals that radio- intrusive breccia texture and apparent com- A related alkaline intrusive complex may oc- activity in this sample coincides with finely posite nature of certain dikes indicate several cur at depth or may be concealed by adjacent disseminated hematite in groundmass car- periods of magmatic activity. Paleozoic and Cenozoic rocks. bonate. Uranium and yttrium characteristic- Experimental evidence indicates that apa- Minor wall-rock assimilation, potassium ally occurtogether in carbonateminerals, such tite is the first mineral to crystallize from a fenitization, and hematization accompanied as in many of the 18 pyrochlore group min- carbonatite melt (Wyllie and Biggar, 1966). emplacement, but they appear to have had erals. When found, these minerals are often Magnetite, the second-formed mineral within only minor effects on final carbonatite com- metamict and fine grained. One of these carbonatites of the Chupadera Mountains, position. Fenite forms a rind up to 0.02 mm minerals may have existed in the Chupadera encases apatite. Biotite followed magnetite thick along dike margins, on adjacent host- Mountains,but was altered.Some of the ura- and was altered before final emplacement. rock fractures, and around wall-rock xeno- nium may have been remobilized in the near- However, biotite within carbonatite frag- liths within the carbonatite. The fenite is a surfaceenvironment and locallvadsorbed bv ments was isolated from late magmatic fluids light-gray to brown replacement, which is hematite. and remains relatively fresh. Probable cal- composed predominantly of potassium feld- Titanium is associatedwith iron in the dikes zirtite or zirkelite crystallized early and was spar. The feldspar is replaced locally by ir- becauseof titaniferousmagnetite, ilmenite, replaced completely by calcite, zircon, and regular patches of carbonate, chlorite, and fine-grained mixtures of iron and tita- ilmenite before final solidification of the car- goethite, and hematite. nium oxides. Lead and zinc are correlative bonatite. Plagioclase, which is completely re- Brick-red hematite extends up to 5 cm be- and probably coexist as trace constituents placed bv carbonate and clav, mav have yond fenitized wall rock as minute grains within severalmajor minerals. briginated as phenocrysts from a precursor along host-rock grain boundaries. Fractures magma. in Precambrian rocks distal to the carbonatite Le Bas (1977\ and numerous other re- dikes are coated locally with hematite. Some Petrogenesis,emplacement, and alteration searchers suggest that a carbonate melt is of these fracture zones are in the trend of The carbonatitedikes were formed by mul- formed as an immiscible phase of a volatile- nearby carbonatite dikes. Sparse hematite is tiple forceful injectionsof carbonatitemagma. rich, alkaline, ultramafic m-agma.Unlike many evenly dispersed throughout primary potas- Part of the melt solidified and was brecciated carbonatites, those in the Chupadera Moun- sium feldspar in the Precambrian rocks. The
May 1986 Nan Mexico Geology to TABLE S-Linear correlation coefficients(r values) of selectedminor and heavy elements, listed in order of abundance. These were based on-up limits' 43 element pairs calculated from analysei summarized in Table 4. Element puirs wet" discarded when there was a value below detection Elementswith no detectionswere Ba (4), Ce+La (4), Th (16),and Rb (14).
El"-"nt F" Mn Ti B" F C" + L" Z. St Nb Y Th ztt Ni Rb u Pb crt -0.32 -0.19 0.53 -0.25 0.23 0.01 0.38 0.11 - 0.04 - 0.36 - 0.19 0.06 0.26 0.05 1.00 Cu 0.42 0.17 -0.24 -0.08 0.09 - 0.31 - 0.03 0.30 0.02 0.52 0.34 0.58 0.22 -0.20 -0.15 0.68 0.14 1.00 Pb -0.28 -0.21 IT - 0.50 0.03 - 0.47 0.25 - 0.04 0.10 -0.14 -0.01 0.03 0.70 0.39 0.72 1.00 -0.06 0.28 -0.03 0.16 -0.28 0.36 0.35 - 0.03 0.L7 0.14 0.36 0.07 0.11 1.00 Rb - Ni 0.58 0.36 0.50 -0.07 0.25 0.43 0.45 0.24 0.28 0.25 0.10 0.15 1.00 -0.51 -0.27 Zn 0.41 -0.29 0.37 0.07 -0.03 0.33 0.28 0.30 0.05 1.00 Th -0.31 0.32 -0.33 0.04 -0.25 0.39 0.20 -0.77 0.09 0.56 1.00 Y -0.42 0.23 -0.42 - 0.01 -0-02 0.26 - 0.05 - 0.26 0.27 1.00 Nb 0.10 0.10 - 0.03 0.02 0.37 0.47 0.37 0.25 1.00 Sr 0.42 -0.11 0.32 0.20 0.27 0.45 0.55 1.00 Zr 0.48 0.40 0.47 0.04 0.40 0.75 1.00 Ce -f La 0.31 0.25 0.06 0.10 0.38 1.00 F 0.35 0.29 0.26 -0.02 1.00 Ba -0.15 0.03 -0.27 1.00 Ti 0.79 0.04 1.00 Mn 0.17 1.00 Fe 1.00 disseminated hematite may be related to host rock. Semiquantitative x-ray fluores- critically reviewed by Theodore J. Armbrust- widespread mild fenitization, but more likely cence (XRF) analyses of seven jasperoid sam- macherand Virginia T. Mclemore. Frederick it formed during deuteric or metamorphic ples reveal maximum concentrations in B. Park, Neil K. Muncaster, and JeffreyL. processesbefore carbonatite magmatic activ- individual samples of 3l% Ba,2Vo Fe, 0.257o Wilson also provided valuablecomments. ity. Zr,0.74VoMn, 560 ppm Th, 560 ppm Cu, 360 Carbonate replacements and minor vein- ppm Y and 56 ppm U. Rare-earth elements References lets of secondary calcite within the carbon- were not detected. Armbrustmacher, T. l. 1979, Replacementand primary atites represent minor recrystallization after Three radioactive, hematitic, quartz veins magmatic carbonatitesfrom the Wet Mountains area, Economic dike emplacement. The recrystallization ap- were found in Precambrian rocks. One sim- Freiront and Custer Counties, Colorado: Geology,v. 74, pp. 888-901 isochem- ilar vein occurs within a carbonatite dike. pears to have been predominantly Arnbrustmacher, T. J., and Brownfield, l. K., 1978,Car- ical. Subsequent partial weathering altered The veins are less than 1 ft in maimum width bonatites in the Wet Mountains area, Custer and Fre- select orthoclase and chlorite to clay and al- and are of short strike length. Semiquanti- mont Counties, Colorado-chemical and mineralogical 78-1.77, tered minor amounts of titaniferous mag- tative XRF analyses of three vein samples data: U.S. GeologicalSurvey, Open-file report b goethite, and leucoxene. contain up to 3.97oFe, 0.46% Zr, 400 Y PP. netite to hematite, PPm Armbrustmacher,T. J., and Hedge, C. E., 1982,Genetic Some porphyritic dikes may be texturally 340 ppm U, and 270 ppm Th. The veins con- implications of minor-element and Sr-isotoPe 8eo- similar to select carbonate rocks in the Wet tain no barite or detectable rare-earth ele- chemistry of alkaline rock complexesin the Wet Moun- Mountains of Colorado (Armbrustmacher, ments. tains area, Fremont and Custer Counties, Colorado: Mineralogy and Pehology, v.79, pp. jasperoid quartz veins Contributions to pers. comm. 1985), which are interpreted to The hematitic and 424-435. be replacements of lamprophyre dikes. These are of uncertain origin. Somewhat similar Beny,L. G., and Mason,B., 1959,Mineralogy-concePts, rocks are named "replacement carbonatites" hematitic ouartz-microcline-barite-carbon- descriotions,determinations: W. H. Freemanand bv Armbrustmacher 0,979\. However, it is ate veins with thorium, yttrium, and rare- Compiny, San Francisco,630 pp. S. A., Kent, S. C., and Sumner,W., 1983,Geol- earth elements occur in other carbonatite dis- Bowring, irirprobable that the carbonatites of the Chu- ogy and U-Pb geochronology of Proterozoic rocks in padera Mountains formed in this manner. tricts such as the Wet Mountains and Pow- the vicinity of Socorro,New Mexico: New Mexico Geo- More likely the petrogt'aphy reflects variable derhorn areas of Colorado and the Lemhi logical Society, Guidebook to 34th Field Conference, instabilitv of phenocrvsts and inclusions Pass area of Idaho and Montana (Phair and pp. 1.37-142. 1974, Radiometric age determinations Fisher, 1961). Brookins, D. C., during niug-uti. emplicement. All pheno- from the Florida Mountains, New Mexico: Geology, v crysts, carbonatite fragments, and, to a min- 2, pp.555-557. imal extent, wall-rock inclusions display Condie, K. C., and Budding, A. 1., 7979,Geology and Age and regional significance partial resorption by carbonate, and most geochemistryof Precambrianrocks, central and south- Carbonatites of the Chupadera Mountains centralNew Mexico: New Mexico Bureau of Mines and phenocryst minerals are chemically altered. 35, 60 pp. and geo- Mineral Resources,Memoir have a mineralogical, geochemical, Eggleston,T. L., 1982,Geology of the central Chupadera logical setting comparable to the late Ordo- Mountains, Socono County, New Mexico: Unpub- Thorium-bearing jasperoid vician carbonatites in the Lemitar Mountains lished M.S. Thesis, New Mexico Institute of Mining and quartz veins (Mclemore, 1983). These carbonatites lie in and Technology,Socono, 162 pp. averageand typical chenical com- to Late Gold, D. P., 1965,The The Caloso Formation (Mississippian) a regional belt of Late Precambrian position of carbonatites;ln Intemational rnineralogical contains jasperoid that can be traced in con- Silurian carbonatites and alkalic rocks, which associationvolume: Mineralogical Societyof India, pp. tinuous outcrop for up to 0.5 mi along strike. extends from southern New Mexico to cen- 83-91. The jasperoid extensively replaced the for- tral Colorado (Fig. 1). The intrusives proba- Kapustin, Y- L., 1,980,Mineralogy of carbonatites(English hanslation): Amerind Publishing Company Pvt. Ltd., mation near the Paleozoic-Precambrian un- bly formed during a period of extensionwithin New Delhi, India,259 pp. conformity. Basal mineralization is dark a zone that approximates the Cenozoic Rio Kent, S., 1982, Geologic maps of Precambrian rocks in reddish brown (because of disseminated Grande rift and possibly a Precambrian rift the Magdalena and Chupadera Mountains, Socono hematite), fine grained, and commonly ra- system. County, New Mexico: New Mexico Bureau of Mines and Mineral Resources,Open-file Report 170,2 maps, dioactive (because of thorium). Portions of Thorium-bearing quartz occurs spatially, scale1:12,000. the jasperoid contain minor calcite, iron- and but probably not temporally, related to car- Kottlowski, F. E., 1960,Summary of Pennsylvanian sec- manganese-oxide joint coatings, and con- bonatites of the Chupadera Mountains. The tions in southwestern New Mexico and southeastern centrations of barite. The silicification has Mississippian or younger thorium-rich jas- Arizona: New Mexico Buteau of Mines and Mineral Resources,Bulletin 66, 187pp. enclosed fine detrital grains of quartz, feld- peroid appears younger in age than the car- Le Bas, M. l. 1977, Carbonatite-nephelinite volcanism, spar (which is partly corroded), and trace bonatites. Additional research on the genesis an African case history: John Wiley and Sons, New muscovite. Carbonate inclusions are abun- of the thorium occurrences is warranted. York,347pp. dant where jasperoid grades into unreplaced ACKNowLEDGlrrNrs-This manuscript was continuedon page40
NewMexico Ceotogy May 1986 cordingly. Generally, only the very best gas lup Sandstone (Upper Cretaceous)of northwestem New Oil and GasJournal, 1985,Selected U.S. and world cmde prospects,or thosegas prospects required to Mexico: New Mexico Bureau of Mines and Mineral Re- prices: Oil and Gas Journal, v. 83, no. 1, p. 120. and Gas al, 1986a,Selected U S. and world crude leases,were 1985. sources,Circular 764, 32 pp Oil Journ hold drilled in However, Cather,S. M., and Johnson, B. D., 1,984,Eocene tectonics prices: Oil and Gas Journal, v. 84, no 2, p. 85. existinggas pools in the San|uan Basincon- and depositional setting of west-central New Mexico Oil and Gas foumal, 1985b,AGA-gas surplus to retain tinued to be developed. and eastemArizona: New Mexico Bureauof Mines and price rein: Oil and GasJournal, v. 84, no. 1, pp 52-53 ACKNowLEDGwNTs-PrentissChilds of the Mineral Resources,Circular 192,33 pp Stamets,R L , Kautz, P, Brooks, L , and Busch,E , 1985, Energy Information Administration, 1985,U.S crude oil, New Mexico: The Oil and Gas Compact Bulletin, v. tl4, New Mexico Oil ConservationDivision pro- natural gas, and natural gas liquids reserues:U S. De- no 1, pp 31-33 vided the well completionstatistics. Richard partment of Energy, Energy lnforrnation Administra- Stone, W J , Lyford, F. P, Frenzel, P F., Mizell, N H , Stametsof the New MexicoOil Conservation tion, 1984annual report, DOE/EIA-0216(84),98 pp and Padgett,E. T.,1983,Hydrogeology and water re- Division provided data on the volume of oil Foster, R W, 1980,Carbon dioxide sourcesand use for sourcesof San Juan Basin, New Mexico: New Mexico enhancedoil recovery: New Mexico Petroleum Recov- Bureau of Mines and Mineral Resources,Hydrologic and gas produced. David Donaldson of the ery ResearchCenter, Report 80-4, 73 pp Report 6, 70 pp New MexicoBureau of Geologyprovided the Kelley,V C , 7978,Geology of EspafrolaBasin, New Mex- Thompson,S, III, 1980,Pedregosa Basin's main explo- reservestatistics. Robert Bieberman,Frank ico: New Mexico Bureau of Mines and Mineral Re- ration target is Pennsylvanian dolostone: Oil and Gas Kottlowski, and Sam Thompson, III, re- sources,Geologic Map 48, scale1:125,000 Journal, v 78, no. 42, pp 202, 207, 21.0,215. Kinney,E E (ed),7967, The oil and gasfields of south- Thompson,S, III, 1981,Petroleum source rocks in ex- viewed the manuscript.Lynne McNeil typed easternNew Mexico: Roswell Geological Society,'1.967 ploration wells drilled to Paleozoicor Mesozoic units, the manuscriptand Cherie Pelletierdrafted Symposium Supplement, 195 pp. Hidalgo and Grant Counties, New Mexico: New Mex- the illustration. Kottlowski, F. E , and Stewart, W J., 1970, The Wolf- ico Energy Institute, Report EMD 2-55-3306,720 pp campianJoyita uplift in cenhal New Mexico: New Mex- Thompson,S, ilI, and Jacka,A. D, 7981,Pennsylvanian ico Bureau of Mines and Mineral Resources,Memoir shatigraph, pehography, and petroleum geology of References 23,pt I, pp 1-31 the Big Hatchet Peak section,Hidalgo County, New American GasAssociation, 1984,The gasenergy demand Meyer, R F, 1955,Geology of Pennsylvanian and Wolf- Mexico: New Mexico Bureau of Mines and Mineral Re- outlook: 1984-2000:American Gas Association,Arling- campian rocks in southeastNew Mexico: New Mexico sources,Circular 1.76,1.25 pp. ton, Virginia, 90 pp Bureauof Mines and Mineral Resources.Memoir 17, Woodward,L A, Callender,JF., Seager,W R, Chapin, Broadhead,R F, and King, W. E, 1985,Preliminary 123pp C E , Gries,J C, Shaffer,W L, and Zilinski, R E , report on the stratigraphy and structure of Pennsyl- Molenaar,C M ,9n, Stratigraphyand depositionalhis- 1978,Tectonic map of Rio Grande rift region in New vanian and lower Permim strata, Tucumcari Basin: New tory of Upper Cretaceousrocks of the San Juan Basin Mexico, Chihuahua, and Texas;inHawley, J W (com- Mexico Geological Society, Guidebook to 36th Field area,with a note on economicresources: New Mexico piler), Guidebook to Rio Grande rift in New Mexico Conference,pp 151-155 Geological Society, Guidebook to 28th Field Confer- ind Colorado: New Mexico Bureau of Mines and Min- Campbell,C.V.,1979, Model for beachshoreline in Gal- ence,pp 159-166 eral Resources,Circular 153, sheet 2 tr
continuedfrom page29 Loring, A K, and Armstrong, D G , 1980, Cambrian- AssociationforWomen Geoscienlists fieldtrip Ordovician syenites of New Mexico, part of a regional alkalic intrusive episode: Geology, v 8, pp 3114-348 Kate Johnson of the USGS, a noted. expert on sand beaches that make some of the b€st campsites' Mclemore, V. T , 7982, Geology and geochemistry of Or- the SalmonRiver area of west-centralIdaho, will in the west. The cost of $300for members and $350 dovician carbonatite dikes in the Lemitar Mountains, lead a three-day trip on the Salmon River on fuly for nonrnembers includes all expenses on the river Socorro County, New Mexico: New Mexico Bureau of 4*6, 1986. The lower canyons of the Salmon River and round-trip transportation-between Grange- Mines and Mineral Resources, Open-file Report 158, r12 pp cut through some of the mo$t spectacularcountry ville, Idaho, and the river, The trip is limited to Mclemore, V T, 1983, Carbonatites in the Lemitar and an,'\^rherein the U.S. Johnsonwill discussthe local 24 people. For information call Marcia Knadle at Chupadera Mountains, Socono County, New Mexico: outcrops ofTertiary and Cretaceou$rocks expos€d (206)593*6510 or JeanneHaris at (303)694*6076, New Meico Geological Society, Guidebook to 34th Field in the canyon dnd the regional geology and tec- or write tor Association for Wbmen Geoscientists, Conference, pp 235-240 tonic setting of the area-In addition, we will hav€ National Field Trip, Box 1005, Menlo Park. Cali- Mclemore, Y. T , 1984, Preliminary report on the geology ample time to study the modern point-bar deposits fornia 94024. md mineral-resource potential of Tonance County, New of the Salmon River, which ar€ exposed as white Mexico: New Mexico Bureau of Mines and Mineral Re- sources, Open-file Report 192,277 pp Olson, J C, Marrrn, R F, Parker, R L, and Mehnert, H. H , 1977, Age and tectonic setting of lower Paleozoic Editor'snote: Becauseseveral articles in this is- alkalic and mafic rocks, carbonatites, and thorium veins Staatz,M H, Adams, J W, and Conklin, N M, 1965, sue include both conventional (American and Brit- in south-central Colorado: U S Geological Survey, Thorium-bearine microcline-rich rocks in the southern ish) and metric units, I have reprinted below the Journal of Research, v. 5, no 6, pp 673:687 Caballo Mountains, Sierra Counfy, New Mexico: U S current Dolicv on use of measurements in Nezrr Phair, G, and Fisher, F C ,1961. Pbtassicfeldspathiza- Geological Survey, Professional Paper 525-D, pp. D48- MexicoGeology. Comments are invited. tion and thorium deposition in the Wet Mountains, D51 Colorado: U S Geological Survev, Professional Paper Wyllie, P J, and Biggar, G M ,1,965, Fractional crystal- The generalpolicy is that measurementsshould 424-D, pp D7-D2 lization in the "carbonatite systems" CaO-MgO-CO5 given Reim, K M , 1955, Mineral resource survey of Pedro Ar- H2O and CaO-CaF5PrOr-COrHzO; ln International be in the unitsor,grrnal/y used and conversions mendaris Grant, New Mexico: United Geophysical Cor- mineralogical association volume: Mineralogical Soci- will not be given in parenthesesunless specifically poration, Unpublished report for Kern County Land ety of India, pp 92-105 n requestedby the author.This means: Company, San Francisco, California, 57 pp 1) Geographicdistances or elevationsin the U.S. shouldbe givenin conventionalunits (miles, yards, feet) regardlessof the kind of mea- surementsused elsewherein the paper. 2) Field,section, fossil, or other measurements Societyof EconomicPaleontologists andMineralogists courses made otiginally in metric units should be re- portedthat way even if this meansthat some May 30, 1986 SEPM short course "Glacial sedimentary environments," in Champaign, Illinois measurementsin the paper are reportedin June 14-15, 1985 SEPM short course "Structures and sequences in clastic rocks." in Atlanta, Geor- standardunits (. . . the study area is 10 miles 8ia. north of Socorro. . .) and some are reported in metric units (. . . the 6-m-thicksec- fune 14-15, 1986 SEPM short course "Modern and ancient deep sea fan sedimentation," in Atlanta, Georgia. tion...; ...we useda 2-mmmesh screen to...). fune 15, 1986 SPEM short course "Paleoclimatology and economic geology," in Atlanta, Georgia 3) Any quotedmaterial must, of course,be iden- ticalto the originalpublished text. Conversion June L5, 1985 SEPM core workshop "Modern and ancient shelf clastics," in Atlanta, Georgia of metersto feet withina quote(. . . "the 6-m- August 7-2,1986 SEPM field seminar, "Paleozoic and Mesozoic rocks of the Golden-Boulder area [19.7-ft-] thick section . . .") is unnecessaryeven and Denver Basrn, Colorado," in Golden, Colorado il in the rest of the paper only standardunits used. For more information or to register for any of the above courses, contact: Joni C. Merkel, Society are of Economic Paleontologists and Mineralogists, P.O. Box 4756, Tulsa, Oklahoma 74159-0756, (9181 4) An exceptionis made on figureswhere we 743-2498. requireone scalebar that has both metricand conventionalunits delineated.
40 May 1986 Nnt Mexico Ceology