tions such as Paramount Canyon, the veins TaylorCreek tin distrisl- may reach three to four centimeters in width and a few meters in height and length. A dis- seminated cassiterite halo has been noted stratigraphy,structure, around the veins in Squaw Creek. A recently discoveredrhyolite porphyry has andtiming of mineralizationintensely altered the surrounding country rock near NM-59 where the road crossesthe Conti- byTed L. Egglestonand David L Norman,New Mexico lnstitute of Miningand Technology, Socorro, NM nental Divide. This porphyry is locally quartz- sericite altered and contains as much as I go pyrite. Similar intrusives have been mapped Introduction The Taylor Creek tin district is located in by Woodard (1982) southeast of the Taylor Primary tin depositscommonly are found in the north-central Black Range some 80 km Creek region. granitic plutonic environments where the tin west of Truth or Consequences,New Mexico occurs as cassiterite in greisen veins and as (fig. l). Cassiteritenuggets were first found in Regional geology disseminations in altered granite (Taylor, placers (Fries, 1940a). in the district in 1909 The tin-bearing Taylor Creek Rhyolite is 1979).In southwest New Mexico, however, tin Shortly wood tin thereafter, cassiterite and located in the Mogollon-Datil volcanic field, a occurs as cassiterite in hematite-cassiterite were porphyritic found in vein depositsin rhy- mid-Tertiary volcanic field consisting of inter- veins which cut Tertiary rhyolite domes and placer (Hill, olite lavas as well as in deposits mediate to felsic volcanic rocks and volcani- flows. This type of tin deposit has been re- l92l). Sincethat time, numerousauthors have clastic sedimentary rocks that unconformably ported at only two other localities in North reported geology, geochemistry, on the and overlie older rocks of various ages.In the Tay- America, Lander County, Nevada (Fries, potential economic of the area, among them lor Creek region, the volcanics overlie Paleo- 1942), and the State of Durango, Republic of (1940a,b), (1942), Fries Fries and others zoic limestones and clastic sedimentary rocks. Mexico (Foshag and Fries, 1942; Pan, 1914: (1972), (1976), (1978), Lufkin Coney Richter Overlying and interbedded with the uppermost Huspeni and others, 1982). These unique tin (1981), (1981). Correa and Goerold Sincethe volcanic rocks is the Gila group, a thick se- depositspresently are the focus of attention by pro- discovery of the tin deposits, the reported quence of coarse clastic sedimentary rocks. various mining concerns, the U.S. Geological placer duction from the depositshas been 9.85 The Gila group was deposited in basins result- Survey, and numerous university research (Volin tons of concentrate averaging 5090 tin ing from the formation of the Rio Grande rift groups. Studies by Charles Maxwell of the and others, 1947). Lode production has been and the Basin and Range province. U.S. Ceological Survey, John Lufkin of the minimal. The Taylor Creek region is part of the Colorado School of Mines, and these authors primary The tin veins consist of hematite Mogollon Plateau, a structurally simple block are aimed at defining the origin of various as- quartz, and cassiteritewith minor amounts of bounded on the west by the Clenwood graben pects of the tin mineralization. In addition, cristobalite, potassium- chalcedony, calcite, and on the east by the Winston graben, both Dave Harvey (University of Texas at El Paso) feldspar, (Lufkin, 1972; heulandite, and topaz of which are related to the Basin and Range is evaluating the economic potential of a por- Goerold, l98l). Theseveins generallyless are province and the Rio Grande rift. The region tion of the region. than wide. in loca- one centimeter but some is a westerly dipping monocline with numer- ous small unconformities suggesting that the central part of the Mogollon Plateau under- went minor subsidencefrom at least 33 m.y. to 2l m.y. ago. The Mogollon Plateauhas inter- acted with the extensional tectonism as an essentially coherent block. The entire block was downdropped, covered with Cila group sedimentary rocks, later /\ uplifted, and is presently being exhumed. The interior of the

o lronMtn Slerr0 C0 uni y \ ALSOIN THIS ISSUE: AlamoBand Navajo Reservationcoal deposits p.5 Stephenson-Bennettmine p.9 9e"JD--Qft -'\ BluewaterLake State Park p.14 -_-.-...J , Service/News p. 16 1982mineral notes p.2O

C(lMINGSOON FloridaMountains overthrust belt Uraniumproduction in NewMexico FIGURE l-LocATloN MAPoF TAYLoRCREEK REcloN (adapted from U.S. Geological Survey map of New Mexico at scaleof l:500,000). block, at least in the Taylor Creek region, Overlying the Hells Mesa tuff is an un- Kline Mountain. The source of the Stiver Can- underwent no significant faulting during the named, poorly to moderately welded, crystal- yon is unknown at this time. downwarping and subsequentuplift. poor, ash-flow tuff as much as 20 m thick. Lit- Several units overlie the tuff of Stiver Can- tle is known of this unit as it is poorly exposed yon at various places. These units include the Volcanic stratigraphy and apparently discontinuous, possibly filling rhyolite of Dolan Peak, the tuff of Kline The following descriptions are based on shallow paleovalleyson top of the Hells Mesa Mountain. and an unnamed red latite lava. field work which is part of the Ph.D. disserta- tuff. The tuff contains approximately 790 The red latite lava is less than 35 m thick and tion of the senior author. The regional map- phenocrysts of feldspar (6%o) and biotite consists of large potassium feldspars (up to 2 ping has been releasedas Open-file Report 177 (190). cm in length) in a red, lithoidal, fine-grained of the New Mexico Bureau of Mines and Min- The basaltic andesite of Poverty Creek (28 groundmass. The base of the unit is a flow eral Resources(Eggleston, 1982b). m.y.; W. E. Elston, 1982,personal communi- breccia; where the unit pinches out east of the The oldest volcanic rocks in the region are cation) consists of interbedded andesite and Continental Divide, a breccia carapace con- approximately 440 m of interbedded, inter- basaltic andesitelavas and brecciaswith green taining vitric clasts of the lava in a very fine mediate-composition lavas, breccias, and volcaniclastic sedimentary rocks separating grained breccia matrix was found. pyroclastic material. (Fig. 2 is a schematic many of the flows. The andesites are fine The tuff of Kline Mountain (new, informal stratigraphic section graphically displaying the grained and contain phenocrysts of pyroxenes name) pinches out against the red latite lava. stratigraphy and geologic relationships in the (?) that have altered to a brown claylike min- This unit is as much as 160 m thick (estimated) Taylor Creek region.) The lavas are andesitic eral. Quartz crystals are locally seen and are along the Continental Divide and pinches out to latitic and generally thin with brecciated- believed to be phenocrysts. Coney (1976) esti- southwest of Kline Mountain. The geometry flow tops and bottoms. Latitic ash-flow tuffs mated that the unit is in excessof 200 m thick. of the unit suggestsdeposition in a basin or are a minor constituent as are volcaniclastic Near the Kline Mountain rhyolite porphyry, broad paleovalley. The unit is a sequenceof sedimentaryrocks (Woodard, 1982).All of the the andesites have undergone mild to intense interbedded ash-flow and air-fall tuffs and units are laterally discontinuous. This se- propylitic alteration. The mildest alteration volcaniclastic sedimentaryrocks. The tuffs are quence has been called the Spears Formation produced epidote along joint surfaces, the crystal-poor to crystal-rich with variable pro- (Coney, 1976)and the Rubio Peak Formation most intense alteration produced a bleached portions of sanidine and quartz with traces of (Woodard, 1982), which are laterally equiva- rock with secondary epidote, calcite, and pos- biotite. The volcaniclastic sedimentary rocks lent. Using the nomenclatureof Osburn and sibly chlorite. Near the contact with the in- are tuffaceous sandstones, siltstones, and Chapin (1983,in press),these rocks are part of trusive, the andesites contain clay minerals pumice-bearing conglomerates.The upper few the Datil Group. The age of the Datil Group that may be due to mild argillic alteration. meters of the unit contain vitric clasts similar spans 37-33 m.y. (Elston and others, 1973; The tuff of Stiver Canyon overlies the basal- to the overlying rhyolite of Dolan Peak sug- Elston, 1976;Chapin and others, 1978). tic andesiteof Poverty Creek and is as much as gesting a genetic relation between the two The Hells Mesa tuff is as much as 150m of 200 m thick (Woodard, 1982). This tuff is units. Alteration related to the Kline Moun- crystal-rich, moderate to densely welded ash- poorly to moderately welded, crystal-poor to tain intrusive has been mild to intense. Near flow tuff erupted from the Socorro cauldron moderately crystal-rich, and white to buff in the contact with the intrusive, an advanced (Woodard, 1982; Eggleston, 1982a).The top color. The unit contains 1-liv/o phenocrysts argillic assemblageof alunite-silica-clayswas of the unit is characterizedby a thinly bedded, of sanidine, quartz, and coppery biotite. Sani- produced. Away from the contact, an argillic poorly to moderately welded tuff as much as dine is the dominant phenocryst with minor assemblageof clay (kaolin?)-silica-alunite was 30 m thick. This unit may representair-fall quartz and a trace of biotite. Pumice is not produced. This is the unit that was mined for and small-volume ash-flow material late in the common, and where it is present it is only eruption of the Hells Mesa. The Hells Mesa slightly collapsed. In the head of Poverty contains up to 5090 phenocrysts consisting of Creek, the Stiver Canyon contains a thin sedi- sanidine, quartz, plagioclase, and coppery mentary rock interval consisting of conglom- biotite in proportions of approximately erates,sandstones, and mudstones. This inter- New AAexnc@ 2:l: l:0.1, respectively.Though the term Hells val is a good marker horizon near the base of Mesa tuff is used for this tuff, the Kneeling the unit, but it pinches out approximately I GEOLOGY Nun Tuff, erupted from the Emory cauldron km south of NM-59 and 2 km east of the Con- . Scionceand Service to the south, is of similar age and lithology so tinental Divide on NM-59. On the north flank Volum€ 5, No. 1, February 1983 the correlation with the Hells Mesa is not en- of Kline Mountain, the entire sectionof Stiver published quarterly by tirely clear. Canyon pinches out and reappears south of New Mexico Bureau of Mines and Mineral Resources a division of New Mexico lnstitute of Mining & Technology

BOARD OF REGENTS Ex Officio Toney Anaya, Covernor ol New Mexico Leonard DeLayo, Srperintendent of Public Instruction RoilroodConvon Tuff Appointcd William C Abbott, 196l-1985, Horbr ToylorCreek Rhyolile Judy Floyd, 1911-1987 , Las Cruces Owen Lopez, 1911-1983, Sonta Fe Toylor Creek Rhyolite Dave Rice, Secty/Treas , 1912-1983, Carlsbad Steve Torres, Pres , 1961-1985, Socorro ooo-ga,oo6" New Mexico lnstitute of Mining & Technology rhyoliteof DolonPk. Acting President Charles R Holmes New Mexico Bureau of Mines & Mineral Resources cgny;T.3 Dircctor Frank E Kotrlowski ivei Deputy Director George S Austin Subscriplions: lssued quarterly, February, May, August, Novembe.; subscription price $6 m/yr Ediloriol matter: Contributions of possible material for consideration in futu.e issues of NMG are welcome Address inquiries !o Marla D Adkins-Heljeson, edito. of rufufuNNN^J -J N/ New Menco Aeobgy, Ne\| Mexico Bureau of Mines & Dotil Group Mineral Resources,Socorro, NM 8?801 Dotil Group Published as public domoin, thereJore rcproducible illhout permiston Source credit requested Circulation: l,M FIGURE 2-Scxpuertc sTRATIGRApHtcsEcrroN sHowrNGsrRATrcRApHy AND cEot-ocrc RELATloNsHlpsrN P.irler. University of New Mexico Printing Plant TnylonCnEex nnctoN

February1983 Ne\| Mexico Geolog! its kaolin content where NM-59 crosses the hydrothermal alteration has locally destroyed basaltic andesite,basalt, and latite with minor Continental Divide. the feldspar phenocrysts and produced adu- interbedded volcaniclastic sedimentary rocks. The rhyolite of Dolan Peak overlies the red laria near the tin-bearing veins (Goerold, Near Wall Lake, the Bearwallow Mountain is latite lava, the tuff of Kline Mountain, and the l98l). divided into two units, the upper Wall Lake tuff of Stiver Canyon. It is a white-to-buff, The Taylor Creek Rhyolite formed domes in andesite and the lower Double Springs Ande- flow-banded, moderately crystal rich rhyolite excessof 300 m high and short, thick flows site. Both of these units consist of multiple lava. The rhyolite consists of phenocrysts of away from the domes. This dome and flow andesite flows locally separated by sedimen- very vis- rocks. The Wall Lake andesite is distin- iridescent sanidine, quartz, and 3 trace of pla- pattern suggeststhat the lavas were tary gioclase in a fine-grained, devitrified, and cous, probably the result of a low-volatile con- guished by the presenceof green pyroxene (W. locally spherulitic groundmass. This unit pin- tent. Deep dissection by Taylor Creek and its E. Elston, 1982, personal communication). ches out east of where NM-59 crosses the tributaries has exposedtwo domes which show Tertiary intrusive rocks Continental Divide and reappears south of a fanlike internal structure. One of these Kline Mountain, but attains a total thickness domes (shown in fig. 3) is immediately down- The only intrusive found to date in the of approximately 130m (Coney, 1976). stream from Wall Lake. whereas the other is Taylor Creek area is a large rhyolite porphyry An unnamed ash-flow tuff overlies the near the mouth of Whitewater Canyon on immediately south of Kline Mountain. This in- rhyolite of Dolan Peak and the tuff of Kline Taylor Creek. The dome near the mouth of trusive is informally referred to as the Kline porphyry Mountain along the Continental Divide. This Whitewater Canyon also shows flow folding Mountain rhyolite in this study. The phenocrysts tuff is denselywelded, crystal-poor, and white related to a lava flow flowing north or north- rock consists of 10-1590 of sani- groundmass. to gray in color. Phenocrysts of sanidine pre- east from the dome (Lufkin, 1972). dine and quartz in a fine-grained dominate with minor quartz. The unit pinches The Railroad Canyon Tuff is about 23.5 Sanidine occurs as euhedral crystals up to I cm out west of Kline Mountain. Vapor-phase al- m.y. old and overlies the Taylor Creek Rhyo- in length and predominates over the small, teration has locally been intense. Pseudo- lite (Elston and others, 1973). This tuff is euhedral quartz by about 2 to l. Near the mar- brookite and bixbyite are frequently found in generally white, poorly welded, and crystal- gin of the intrusive, vertical flowbanding is pumice fragments. Correlations with this tuff rich in the Taylor Creek area, but crystal-poor common. Woodard (1982) mapped several are unknown, but Elston and Northrop (1976, phases have been reported in other areas similar intrusives south of the area of interest editors' note, p. 35) suggestthat the unit may (Woodard, 1982;W. E. Elston, 1982,personal of this study. Intrusion of this rhyolite has correlate with the rhyolite of Diamond Creek communication). This leads to the possible caused gentle doming of the overlying volcanic of Ericksen and others (1970). correlation of a seriesof tuffs that overlie the rocks. is altered to some de- The tin-bearing Taylor Creek Rhyolite is the Taylor Creek Rhyolite near the mouth of The entire intrusive gree. intense alteration is located next younger unit in the stratigraphy. Work to Whitewater Canyon with the Railroad Canyon The most margin of the intrusive date suggeststhat it was erupted as domes and Tuff (W. E. Elston, 1982, personal com- near the northern quartz-sericite-pyrite was flows about 25 m.y. ago (Elston and others, munication). The phenocrysts in the Railroad where alteration by 1973; R. H. Weber, personal communication, Canyon consist of quartz, irridescent sanidine, found. This alteration is characterized sili- feldspar to coarse 1982).The Taylor Creek Rhyolite is a seriesof and minor biotite. The total thicknessis 20-40 cification, alteration of white, very crystal-rich, flow-banded, rhyolite m near the Continental Divide. The source of white mica, and by the addition of approxi- pyrite to lavas covering an area of approximately 450 the Railroad Canyon is unknown. mately 0.590 fine-grained, euhedral breccia bodies were mi'z. The phenocrysts are quartz and sanidine The Jordan Canyon formation, represented the rock. Locally small quartz veinlets in varying proportions with minor biotite. An by a thin volcaniclastic sedimentary rock in- found that were cemented by pyrite. pyrite is exception to the above generality is the Taylor terval near Wall Lake locally overlies the that contain rare This the only associatedwith the al- Creek Rhyolite exposed on the north rim of Taylor Creek Rhyolite and the Railroad Can- metallic mineral found pyrite diminishes, the Paramount Canyon. This lava contains only yon Tuff (Elston, 1976). West of the Taylor teration to date. As the l5-200/o phenocrysts but is mineralogically Creek region, the Jordan Canyon intertongues alteration changes to an advanced argillic as- and texturally similar to other Taylor Creek with the Bearwallow Mountain Formation semblage of silica-alunite-clay near the north exposures. Volcaniclastic sedimentary rocks which consists of a thick pile of andesite, and tuffs are frequently found between the rhyolite lava flows and in basins between domes. The pyroclastic material is believed to be cogenetic with the rhyolite lavas and indi- cates periods of explosive volcanism associ- ated with the emplacement of the rhyolite domes. Vapor-phase alteration of the Taylor Creek Rhyolite has locally been intense. The effects of this alteration are similar to argillic altera- tion in that clays have been produced in the groundmass of the rhyolite, but, in general, the feldspar phenocrysts have been unaf- fected. Lithophysae are generally lined with drusy coatings of quartz, hematite, pseudo- brookite, bixbyite, and rare topaz, red beryl, and chalcedony (Ericksen and others, 1970; Lufkin, 1972, 1976; Kimbler and Haynes, 1980; and Narsavage, l98l). Cassiterite has been reported from the lithophysae (Lufkin, 1972), but subsequent studies have failed to locate that occurrence(C. Maxwell, 1982, per- sonal communication; F. Kimbler, 1982, per- sonal communication). Later, hydrothermal argillic alteration has overprinted the vapor- phase alteration near the tin occurrences.Dis- FIGURE 3-Tlylon Cnssr RHyor-rrE wESr or Wnll LAKE; note fanlike nature of flow banding. This tinguishing the events is difficult, but the structure is common in domes of Taylor Creek Rhyolite.

New Mexico Geology February1983 W. T., 1981, Ceology and geochemistry of tin oc- The southern part of ACKNOWLEDGMENTS-This report is part Goerold, margin of the intrusive. currences in southwestern New Mexico: M'S. thesis, the intrusive and the surrounding felsic vol- of the Ph.D. dissertation of the senior author Pennsylvania State University, l3l p canic rocks show moderate to intense argillic that is supported in part by the New Mexico Hill, J. M., 1921,The Taylor Creek tin deposits, New Mex- geology-1921' F L alteration characterized by the assemblage Bureau of Mines and Mineral Resourcesand ico, in Contributions to economic E. F. Burchard, editors: U.S. Geological These altera- by grant number G5ll 4031 from the Office Ransorne and clay-minor silica-minor alunite. Bull. 725, p. 341-359 Inter- Survey, tion assemblagesare more or less "normally" of Surface Mining, Department of the Huspeni,J. R., Kesler,S. E., Ruiz, J., Tuta, Z. H., Sutter, zoned around the northern end of the intru- ior. I thank W. E. Elston of the University of J F., and Jones, C. M., 1982, Geochemistry and origin sive. New Mexico and Charles Maxwell of the U.S. of the Mexican tin belt (abs.): Geological Society of Programs, v 14, no. 1, p. 520 Geological Survey for many hours of valuable America, Abstracts with Kimbler, F. S., and Haynes, P. E., 1980, An occurrence of Timing of mineralizing events discussionson the Taylor Creek region stratig- red beryl in the Black Range, New Mexico: New Mexico Two periods of alteration and mineraliza- raphy and ore deposits. Various claim owners Geology,v.2, p. l5-16 including Bob Kerr, FRM Minerals, and Lufkin. J. L., 1972,Tin mineralization within rhyolite flow tion have been defined in the Taylor Creek re- Mexico: Ph.D. dissertation, Danny Fowler have provided accessto their domes, Black Range, New gion. The oldest period is associatedwith the Stanford University, 148 have on the P. Taylor Creek Rhyolite and consists of argillic properties and to information they Lufkin. J L., 1976, Oxide minerals in miarolitic rhyolite, Bureau The American Mineralogist, alteration and hematite-cassiterite veining. area. G. R. Osburn of the New Mexico Black Range, New Mexico: of Mines and Mineral Resources read and v . 6l , p. 425-43O The other event is associated with the Kline at Taylor Creek, Sierra greatly improved the original manuscript' Narsavage, R. S., 1981, Cassiterite Mountain rhyolite porphyry and consists of County (abs ): New MexicoGeology, v' 3, p l6 argillic, advanced argillic, and quartz-sericite- Osburn, G. R., and Chapin, C. E., 1983,Nomenclature for pyrite alteration. The hydrothermal alteration Cenozoic rocks of northeast Mogollon-Datil volcanic Mexico: New Mexico Bureau of Mines and of the Taylor Creek Rhyolite crosscuts the field, New References Mineral Resources,Stratigraphic Chart l, in press vapor phase alteration and does not affect the Pan, Y. S , 19'74,The genesisof the Mexican type tin de- Chapin, C. E., Chamberlin,R M., Osburn, G. R., White, overlying Jordan Canyon formation or the posits in acidic volcanics: Ph.D. dissertation, Columbia D. P., and Sanford, A. R., t978, Exploration framework University, 286 p Railroad Canyon Tuff dated at 22.2 m.y. and of the Socorro geothermal area, New Mexico, in Field Richter, D. H., 1978, Geologic map of the Spring Canyon 23.5 m.y. This restricts the time of alteration guide to selectedcauldrons and mining districts of the quadrangle, Catron County, New Mexico: U.S Geologi- Datil-Mogollon volcanic field, New Mexico, C. E. and mineralization of the Taylor Creek Rhyo- cal Survey, Miscellaneous Field Study Map MF-966' Chapin and W. E. Elston, editors: New Mexico Geologi- lite to 1.5 m.y. immediately following the scalel:24,000 cal Society, SpecialPub.7,p. l14-129 Taylor, R. G , 1979, Geology of tin deposits: Amsterdam, eruption of the lavas. Coney, P J-, 1976, Structure, volcanic stratigraphy, and Elsevier Scientific Publishing Company, 543 p Since the Kline Mountain rhyolite porphyry gravity across the Mogollon Plateau, New Mexico, in Volin, M. E., Russell,P. L, Price, F. L. C., and Mullen, Cenozoic volcanism in southwestern New Mexico, W. E. is not dated, it is difficult to assign a time of D. H., 194?, Catron and Sierra Counties tin deposits, Elston and S. A. Northrop, editors: New Mexico Geolog- mineralization, but the intrusive cuts across New Mexico: U.S. Bureau of Mines, RI 4068, 60 p. ical Society, Special Pub. 5,p 29-41 Woodard, T. W., 1982, Geology of the Lookout Mountain the rhyolite of Dolan peak and has altered the Correa, B. P., 1981, The Taylor Creek Rhyolite and asso- area, northern Black Range, Sierra County, New Mex- unnamed ash-flow tuff above it. The intrusive ciated tin deposits, southwestern New Mexico: M.S ico: M.S. thesis, University of New Mexico ! has also warped the Taylor Creek Rhyolite thesis,Arizona State University, 105 p. and possibly the Railroad Canyon Tuff. This Eggleston, T. L., 1982a,Ceology of the central Chupadera Mountains, Socorro County, New Mexico: M.S. thesis, indirect evidence places the alteration at post New Mexico Institute of Mining and Technology, 164 p 23.5 m.y., and it may be much younger. -, 1982b, Geologic map of the Taylor creek tin dis- trict, Black Range, New Mexico: New Mexico Bureau of Conclusions Mines and Mineral Resources,Open-file Rept. 177 Elston, W. 8., l9?6, Glossary of stratigraphic terms of the Two periods of mineralization have been Mogollon-Datil province, New Mexico, in Cenozoic vol- defined in the Taylor Creek region. The older canism in southwesternNew Mexico, W. E. Elston and S. DescriptionofGibola County A. Northrop, editors: New Mexico Geological Society' is 25-23.5 m.y. old and consists of hematite- p. SpecialPub. 5, 131-144 Following is the geographic description of Cibola cassiteriteveins deposited in the Taylor Creek Elston, W E., and Northrop, S. A., editors, 1976, Ceno- County as it was created by House Bill 373 during Rhyolite. The other period of mineralization is zoic volcanism in southwestern New Mexico: New Mex- the first session of the 35th New Mexico legislature associatedwith a rhyolite-porphyry intrusive ico Geological Society, SpecialPub. 5, l5l p. w. P. E., Coney, P J., Rhodes,R. C., in 1981. that has altered and domed older rocks. The Elston, E., Damon, Smith, E. I., and Bikerman,M.,1973, Tertiary volcanic Section 1. Cibola County created.-The county of age of theseintrusives is post 23.5 m.y., and rocks, Mogollon-Datil province, New Mexico and sur- Cibola is hereby created out of portions of Valencia they may be much younger. No economic min- rounding region-K-Ar dates, patterns of eruption, and County lying and situate within the following eralization has yet been found associatedwith periods of mineralization: Geological Society of Amer- ica, Bull., v. 84, p. 2,259-2,214 boundaries. to wit: the rhyolite porphyry intrusive. to Sec- Elston, W E , Rhodes,R. C., Coney, P. J., and Deal, E. Beginning at the southeast corner common The Taylor Creek tin district is located on G., 1976, Progress report on the Mogollon Plateau vol- tions 10,11,14,and 15 T4N, R4W NMPM and the western margin of the Mogollon Plateau, a canic field, southwestern New Mexico, No. 3-Surface running northerly along a line being parallel to mid-Tertiary volcanic plateau consisting of expression of a pluton, in Cenozoic volcanism in south- and lying two sections west of the fourth range A. Northrop, major volcanic assemblages.These as- western New Mexico, W. E. Elston and S. line west of NMPM and extending through Town- four Mexico Society, Special Pub' 5, editors: New Geological ships 5,6,7 and 8 north to the southerly township semblagesare l) a lower, intermediate compo- p 3-28 line of Township 9 north, thence easterly along an sition assemblageof volcanic and volcaniclas- Ericksen, G. E., Wedow, H., Jr., Eaton, G. P., and extension of said southerly township line to the tic rocks (Datil Group), 2) an assemblageof Leland, G. R., 1970, Mineral resources of the Black primitive Coun- present Bernalillo County line, thence northwest- lavas related to cauldron Range area, Grant, Sierra, and Catron ash-flow tuffs and ties, New Mexico: U.S. Geological Survey, Bull. l3l9-E, erly along such Bernalillo County line to the pre- activity (Hells Mesa, Stiver Canyon, Railroad 162p sent Sandoval County line, thence northwesterly Canyon, and the two unnamed ash-flow Foshag, W F., and Fries, C., 1942, Tin deposits of the along the Sandoval County line, thence westerly tuffs), 3) a bimodal assemblagethat is inter- Republic of Mexico: U.S. Geological Survey, Bull. 935- along the Sandoval County line to the present Mc- p.99-176 with secondassemblage (the basal- C, Kinley County line, thence following said McKin- bedded the Fries, C., 1940a, Tin deposits of the Black Range, Catron ley County line south and then west to the present tic andesite of Poverty Creek, red latite lava, and Sierra Counties, New Mexico: U.S. Geological Sur- south along the state line to the rhyolite of Dolan Peak, tuff of Kline Moun- vey, Bufl. 922-M, p. 355-310 state line thence -, present Catron County line, thence easterly along tain, Taylor Creek Rhyolite, Jordan Canyon 1940b, Geologic map of the Black Range tin dis- trict, New Mexico: U.S. Geological Survey, Strategic the Catron County line and the present Socorro formation. and Bearwallow Mountain Forma- Minerals Investigation, preliminary map County line and finally to the beginning at the younger tion), and 4) a bimodal assemblage Fries, C., 1942, Tin deposits of north Lander County, southeast corner common to Sections 10, 11,14 gtl-L, p. (unnamed basalts interbedded in the Cila Nevada: U.S. Geological Survey, Bull. 279- and 15 T4N, R4W NMPM. group in the Winston graben). The Kline 294 1942, Bixbyite Mountain rhyolite porphyry may be a subvol- Fries, C., Schaller, W. T., and Glass, J. J., and pseudobrookite from the tin-bearing rhyolite of the canic equivalent of the fourth assemblage,but Black Range, New Mexico: The American Mineralogist, its age and chemistry are unknown. v . 27 , p. 305-322

February1983 New Mexico Geology