led to the depositionof potassiumsalts, some Potashin NewMexico of the most soluble (and nearly the last) minerals to be depositedfrom evaporating byGeorge S. Austin,Deputy Director, New Mexico Bureau of Mines& MineralResources, Socorro, NM seawater. Carlsbadmining district New Mexico containsthe nation's largest ment began setting minimum prices and The potashminerals were concentrated in a potash known concentrationof reserves.In cutting back production. These actions re- small area on the west side of the Permian production 1978, in the state totaled 1.92 sulted in market prices high enough to con- Basin.Today, this area-known as the Carls- million metric tons of concentrate-about85 tinue mining the lower grade Carlsbad ores. bad mining district-is astride the Capitan percent (United pro- of the domestic States) Double-digit inflation of the 1970's, however, reef, a prominent geologic structure that percent duction-or 3l of the domestic wiped out much of the profit. By mid-1970's separatesthe DelawareBasin from the north- (Singleton, pro- demand 1978).Potash is the com- New Mexico's deposits were near the low westernshelf in the westernpart of the Per- (in mon term for compoundscontaining the ele- fit levels terms of constant dollars) of the mian Basin.The Capitanreef is exposedat the ment potassium.Natural potassium-bearing problems early 1960's. To compound the of surfacein the mountainssouthwest of Carls- greatest compoundsof importanceare the sol- costs and profits, the ores mined today are bad. In the vicinityof the potashmines, this (KCl) ublemineral salts, especially sylvite and lower grade and contain larger amounts of in- reef, shownin fig. 3 (the CapitanLimestone), (KrSO. langbeinite 2MgSo,), the dominant soluble clays that tend to require additional is deeplyburied beneaththe Ochoanevapor- potash ore mineralsin the United States.The chemical treatment in the mills, thereby in- ites.Ochoan rocks include the Castile, Salado, principal (about percent) use 95 of soluble creasingprocessing costs. and RustlerFormation, primarily a sequence potash mineralsis in manufacturedfertilizers. Thick sections of salt and other evaporite of marine evaporites.The McNutt potash Potassiumis essentialto plant metabolism- minerals in the Permian Basin of west Texas zone. the middle memberof the SaladoFor- no alternativeexists. Nor can potash be re- and southeastern New Mexico (fig. 2) were mation, containsll potashore zones(fig. ). cycled. The lst, 3rd, 4th, 5th, 7th, and l0th zones potassium The contentof fertilizersis com- have proved concentrationsof potash, the monly reported in percent of K'O, even greatesttonnages being produced from the lst present. thoughan oxide is not For example, andlOth. the mineral sylvitecontains about 52 percent The surfacerelief in the Carlsbaddistrict potassium by weight;however, in converting averagesa few hundred feet. The surfaceis percent, to the KzO equivalent sylviteis rated characterizedby dunefields as well ascollapse percent. at 63.17 In other words, every 1,000 featurestypical of karst or sinkholetopog- pure lbs of sylvitecontains about 630 lbs of raphy. The soilshave developed under mixed KzO (or about 524 lbs of elementalpotas- shrubsand grassescommon to the semiarid sium). Langbeinite, the other principal continental climate of the southern High domesticore mineralof potassium,is ratedat Plainsprovince. Most of the soilshave devel- percent 22.69 K,O equivalent.Although con- oped calichesand gypsum and have been tainingless potassium, the langbeinite product workedby thewind. The Carlsbad mining dis- is also low in chloride ion for which some trict has no cities or towns; other than the plants have low tolerance.In addition, both structuresrelating to potashmining, only oil- the magnesiumand sulfateions in langbeinite well sitesand a few ranchesdot the landscape. aid in conditioninghighly leached soil. The sparselyvegetated land is capableof sup- Potash from U.S. mines-chiefly in the portingonly a few headof cattleper section. Carlsbad mining district-supplied the na- tion's needsfor many yearsuntil 1962,when imports, primarily from Canada, increased Identificationof potashlands dramatically.Since then, domestic production F.i..j Area underlainby TheConservation Division of theU.S. Geo- IlE has remainedfairly constant while imports Ochoanevaporites logical Surveyreceives all drill-hole informa- have continuedto increaseand now account FICURE 2-RectoNeL TNDEXMAP tion for federaland stateland in the Carlsbad for morethan two-thirdsof the potashused in mining district. The U.S. GeologicalSurvey the United States(fig. l). Canadianimports hasdefined the Carlsbad enclave (fig. 5) as the come principally from the province of Sas- depositedin a shallowbut subsidingbasin dur- land within the district containing minable katchewan;in 1970the Saskatchewangovern- ing Ochoan(Late Permian)time about 250- quantitiesof potash. Minable quantitiesare 225 million years ago. During the Ochoan, definedas bedsat least4 ft thick containingat marine waterswithin the basin were replen- leastl0 percentK:O assylvite or at least4 per- 60 ished,and dissolvedsolids in the water were cent KzO as langbeinite.All drill-hole in- being continually concentratedby evapora- formation is confidentialand can be released tion. Continued evaporation/concentrationonly by the companiesinvolved. The informa- tza a F Y o roob o, 80 c o c. \--k-::!-_t 60o 2: Exporl s 20o '7 71 73 75 7 ^0 FIGURE l-U.S. porASHMARKET 1965 ro 1978. FICURE 3-Sct-tEuertc sourH-NoRTHcRoss sEcrroN AcRoss ClnLssno N4rNlNCDIsrRIcr New Mexico Geology February1980 tion, however, is used to prepare open-file maps showing the boundariesof the enclave, F mined-out areas, and barren zones. These z maps are updated annually with new drilling l and mining data. Although each of the I I ore zones is fairly continuous within the enclave,minable con- centrations of potash-bearing minerals are restricted to certain smaller areas. Jones and Madsen (1968) have shown the variability of the 5th ore zone in the district; apparentlythe other ore zones have equal variability in minable concentrations.Barren zones within the enclave have resulted either from non- deposition or removal of potash minerals within the Permian sea. later mobilization of the valuableminerals, or both. Thus, drilling programs are used extensivelyby companies searchingfor potash. Both chemicalanalyses of the cores and geophysicallogging of the drill holesserve to identify areasof concentra- tion of the valuablepotash minerals. (obondoried)l{ Mining and milling All minesin the Carlsbaddistrict are under- ground with vertical shafts varying in depth from 650 to 1,750ft. To the westof the district METERSBELOW RUSTLERSALAOO CONTACT UN T r50 - Voco Tr sle Sand FICURE 5-CenLsslo TNCLAvEINcLUDINC MTNES AND MILLS the soluble potash minerals have been re- on the east side of the I ih ore zone moved by solution; i,lorker bed No | 7 district the beds dip about l' to the east, are deeplyburied, and are of lower grade. Shafts are either drilled with large-diameter drilling Morker bed No I I machinesor drilled and blasted with conven- tional shaft-sinkingequipment. Ground water Morker bed No i I is scarce, therefore not commonly a problem lOlh ore zone in sinkingshafts. The ore zones are nearly flat lying; the lVorker bed No l2O 9lh ore zone potash ore is mined with slightly modified Morker bed No l2l Room z ^^^ conventional coal-mining equipment. ft Morker bed No 22 and pillar workings are commonly 5-6/z 8lh ore zone high; as much as 70 percent of the ore is o removed during the first stage of mining. | 2to Some operations also use a second stage- J union Anhyarrre pillars from a z robbing the during withdrawal j mine, allowing overlying rock to 7lh ore zone section of 6lh ore zone settle slowly. In this manner, as much as 92 5lh ore zone percent of the ore may be removed. Subsi- dence fractures have been observedin the land surface above workings that have collapsed at ) Morker bed No 123 r lSJl-'Jio.ti/SlLfiJ_oj'.1|,:.o*",,,*,," .,.u,, depths of 1,000 ft or more. With few excep- I ixB tions only a single ore zone is worked in a I Morler bed No t24 given mine. Even in multilevel mines, how- W) ,otrno. r, zonesare seldom worked if 4lh Ore zone r / /,/,/) ever, overlying ore underlying ore zoneshave been mined. 3 rd ore zone N 2nd ore zone ANHYOR]TE N\\ Other occurrences Morker bed No 125 In a well drilled in Lincoln County, 10-15 ft of tsl ore zone f___l ,o.,-. aND.HALY HALTTE mi northwest of Carrizozo, nearly 2,000 halite has been reported in the Yeso Forma- Morker bed No 126 t==t tion (Lower Permian). Although the well log srarv, sANoY HALrE l-.----l also indicates limestone, sandstone,shale, and FIGURE 4-ColulrNen sEcrroN THRoucH McNurr porASH zoNE anhydrite are present in the interval, potash- (after Jones, Bowles, and Bell, 1960). bearing salts are not mentioned. February1980 New Mexico Geology The Paradox Member of the Hermosa For- Zeller Peak named in Big Hatchet Mountains (Pennsylvanian) is recognized in the name Zeller Peak for mation In September, 1979, the U.S. Board of Geographic Names approved the northwest New Mexico. Mountains of Hidalgo subsurfaceof extreme the prominent peak 2 mi north of Big HatchJt Peak in the Big Hatchet the mineralogy of the salts, a detailed geologic Information on county, New Mexico (fig. l) in honor-of Robert A. zeller, Jr', who compiled quality, is not available, framework for the their or thickness -up of these rugged mountains and established the basic stratigraphic potash salts are produced from this Memoir l6 and Cir- although region. Zeller, whose work on the Big Hatchet area has been published in Paradox Basin of southeastern killed in March 1970 interval in the cular 146 of the New Mexico Bureau Jf Min.r and Mineral Resources,was A' Wengard later Utah. when the aircraft he was piloting crashed in southeasternArizona' sherman to br. Zeller for the 2lst field conference guidebook of the New Summary prepared a memorial tribute Mexico Geological Society (1970). The demand for fertilizers and potassium will increase in accordance with projected in- creases in world food needs.