arizona geology - summer 1989azgeology.azgs.arizona.edu/.../arizona_geology/...the arizona...
TRANSCRIPT
Investigations • Service It Information
Overview of the Geology and Mineral Resourcesof the Buckskin and Rawhide Mountains
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Lineated mylonitic rocks in metamorphic core complexes
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Figure 1. Map of Arizona showing the three physiographic provincesin the State and· the locations of lineated mylonitic rocks in metamorphic core complexes. BUC =Buckskin Mountains; CR =Santa Catalina- Rincon Mountains; RAW = Rawhide Mountains; SAC = SacramentoMountains; SM =South Mountain; WH = Whipple Mountains.
areally extensive exposures of a detachment fault and itsmylonitic footwall.
Evidence of mineralization is abundant along the Buckskin-Rawhide detachment fault, including economic deposits ofcopper and gold. Detachment-fault-related mineralization isnowhere better displayed in North America than in and aroundthe Buckskin and Rawhide Mountains. This type of mineralization was first recognized in the southwestern United Statesin the late 1970's (Reynolds, 1980; Wilkins and Heidrick, 1982).
. The existence of geologically similar deposits has been proposed(continued on page 6)
Introduction
The Arizona Geological Survey has made a major effortduring the past 5 years to understand the geology and mineralresources of the Buckskin and Rawhide Mountains. The resultsof these studies and several studies by other geologists arepresented in the Arizona Geological Survey Bulletin 198, fromwhich the following text has been excerpted. This technicalbulletin, which is now in press, represents a major addition tothe geologic literature on the State and should be of interestto anyone concerned with the geology and mineral deposits ofwest-eentral Arizona.
by Jon E. Spencer and Stephen J. ReynoldsArizona Geological Survey
Crustal extension and compression, involving large horizontal movements of the Earth's crust, are major processesthat have shaped the crustal architecture of planet Earth.Compression has long been recognized as the chief architect ofmost mountain belts and is now moderately well understood. Incontrast, the contribution of extension to the structure of thecrust is less well understood because many extensional structures were only recently recognized and because areas affectedby crustal extension are typically buried by sediments.
Cenozoic extension in western North America has left ageologic record that, for areas of extensional tectonism, is1.ffisurpassed in its visibility. Geologic features related toCenozoic extension are especially amenable to study in the aridsouthwestern United States where bedrock exposure approaches100 percent. Approximately 25 mountain ranges or groups ofr~ng:s in western North America are characterized by a distInctlVe association of geologic features that defied interpretation until the early 1980's. These ranges or groups of ranges~re commonly referred to as metamorphic core complexes. Distmguishing features. include a major low-angle normal fault(r:ferred to as a detachment fault) that separates brittlelydIstended and generally highly faulted rocks above the faultfrom crystalline rocks below the fault that commonly have a9Tntly to moderately dipping mylonitic foliation. Most geologIsts now interpret such faults and foliations as products ofarge-magnitude crustal extension. These distinctive featuresave been recently recognized in parts of Greece, China, andew Guinea, which indicates that Cordilleran metamorphic coremplexes are not idiosyncrasies of western North America
eology, but are general products of extensional tectonism. Theckskin and Rawhide Mountains, which are part of the Harcur metamorphic core complex in west-eentral Arizona (Rehrigd Reynolds, 1980), contain one of North America's most
Figure 1. Value of nonfue1 mineral production in the Southwest, 1987 and 1988. Backgroundphoto: View of the New Cornelia open-pit copper mine near Ajo, Arizona. This currentlyinactive mine is within the Ajo mineral district, which produced from 1899 to 1979, 6 billionpounds of copper, 19.7 million ounces of silver, 1.6 million ounces of gol4, 450,000 pounds ofmolybdenum, and 30,000 pounds of lead. Photo by Peter Kresan.
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internationaland consumerswas reached on arole for the forum and on inclep>endellcefrom the United Nations Conf€~rellCe onTrade and Development.
As in previous years, exploration forgold far outpaced that of other commodities both at home and abroad. Abouttwo dozen new gold mines began production in the United States during1988, and several established producersexpanded capacity. A number of domesticand international companies with goldmining interests consolidated, merged, orspun off their mining operations intoindependent corporations devoted solelyto mining gold. Domestic production ofgold and silver increased. Althoughaveraging slightly higher during most ofthe year, price levels for gold and otherprecious metals declined toward yearend.
Zinc mine production in 1988 rose forthe second consecutive year after fallingcontinuously in the prior 6-year period.The increase was partly due to a fullyear's production of coproduct zinc atprecious metal mines in the West. fA
The U.S. District Court of Appeals 0.,the District of Columbia ordered theEnvironmental Protection Agency (EPA)to relist six wastes from the smeltingand refining of aluminum, copper, ferroalloys, lead, and zinc as hazardousunder subtitle C of the Resources Conservation and Recovery Act (RCRA).The EPA was also ordered to reinterpretthe Bevill amendment to the RCRA. Thisamendment excludes wastes from the"extraction, beneficiation, and processingof ores and minerals" from regulationunder RCRA subtitle C until the needfor such regulation is studied. Althoughthe range of the amendment has beenclearly understood, its application toprocessing ores and minerals has beenless clear. Under the court order, theEPA p~oposed a list of wastes specifical-ly excluded as Bevill wastes. Those thatdo not fall under the Bevill exclusionwill be subject to regulation after therule is finalized.
The EPA was also evaluating a strict-er National Ambient Air Quality Standard that would lower the content oflead in air and impose additional costson domestic lead smelters. The world'slargest producer of secondary lead announced that it would convert its plant~to a new electrowinning process, thus~becoming the first U.S. lead firm tomove toward pollution-free technology.
Bureau of Mines,P.O. Box 18070, Pittsburgh, 15236.
The State summaries were preparedby State mineral officers from theBOM, in cooperation with the respectiveState mineral agencies. Individual summaries are also published separately asState Mineral Industry Surveys. Copiesare available from the respective Statemineral officers: Michael N. Greeley,201 E. 7th St., Tucson, AZ 85705 (Arizona, New Mexico, and Utah); Fred V.Carrillo, 1605 Evans Ave., Reno, NV89512 (California and Nevada); and JaneP. Ohl, Bldg. 20, Denver Federal Center,Denver, CO 80225 (Colorado).
u.s. Summary
The value of nonfuel mineral production in the United States increased 16percent in 1988, from $26.3 billion to$30.5 billion, due to higher demand andprices. Metals and industrial mineralsaccounted for 34 and 66 percent of thetotal value, respectively. The value ofmetal production surged 40 percent in1988, from $7.4 billion to $10.4 billion,whereas the production value of industrial minerals rose only 6 percent, from$18.9 billion to $20.0 billion.
Copper prices, driven by tight supplyand record-low stock levels, averagedmore than $1.00 per pound during 1988.
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In 1988 the value of nonfuel mineralproduction in the Southwest· reached$9.9 billion, a 30.5-percent increasefrom the 1987 value of $7.6 billion (Figure 1; Table 1). Production value inthe Southwest accounted for 32.6 percent of the total value for the Nation,estimated to be $30.5 billion in 1988.For the purposes of this article, theSouthwest includes Arizona, California,Colorado, Nevada, New Mexico, andUtah. In 1988 the Southwest boastedthe three leading producers of nonfuelminerals in the Nation: California,Arizona, and Nevada. Two other States,New Mexico and Utah, held the 10th and11th positions, respectively. Coloradoranked 27th in the Nation.
These preliminary figures were published by the U.S. Bureau of Mines(BOM), which has released State-byState estimates of nonfuel mineral production for 1988. These estimates, basedon 9 months of data, have been published for the first time in one volume:State Mineral Summaries--1989. Thisreport is designed to be a companionvolume to another BOM publication,Mineral Commodity Summaries--1989,which contains national statistics on theproduction of 82 nonfuel minerals. Excerpts from both volumes appear below.Single copies of each are free from thePublications Distribution Section, U.S.
2 Arizona Geology, vol. 19, no. 2, Summer 1989
Table 1. Value of nonfuel mineral production in the Southwest, measured by mine shipments, sales, or marketable production, including consumption by producers. All figuresare from the U.S. Bureau of Mines; totals for 1988 are preliminary estimates.
The EPA's National Effluent Guidelines for gold-placer mining becameeffective on July 7, 1988. Studies bythe U.S. Department of the Interior
_indicate that up to 75 percent of the..... small placer mines will close if these
regulations are implemented.Demand for building and construction
materials, such as construction aggregate, gypsum, and cement, remainedstrong in 1988. Demand for cementnearly equaled that of the record established in 1987. Domestic productiondeclined slightly while imports continuedto make inroads into domestic markets.Imports of 17 million tons were slightlybelow the record level of 1987. Canada,Greece, Mexico, and Spain were theprincipal suppliers of the importedcement, accounting for 75 percent of theimports. Domestic cement-productioncapacity owned by foreign firms reached62 percent in 1988 compared with 22percent in 1981. For the first time, Japanese producers became owners of U.S.capacity by purchasing cement plants inArizona and southern California.
The crushed stone industry, continuing the healthy growth trend that beganin 1984, reported record production.The gypsum industry continued its strongperformance, but because of reduction innew housing construction, output was
fA.... slightly below the record high of 1987._ The EPA continued to analyze the
impact of the proposed ban and phaseoutof asbestos and asbestos products. Inearly 1988, the EPA released its regulatory impact analysis, an assessment ofexposure to asbestos and nonasbestosfibers, and a profile of the nonasbestosfiber industry.
In September, the President signed aU.S.-Canadian free-trade agreement thatwill eliminate all tariffs and most nontariff barriers between the two countriesby 1999, thereby creating the world'slargest open market. In 1987 U.S.-Canadian bilateral trade totaled $161 billion.
Trade expansion is expected to generate5-percent higher growth for Canada andup to 1-percent higher growth for theUnited States by the end of the century.For the United States, that translatesinto 750,000 jobs and $2.4 billion inexports. Canadian parliamentary approval of the agreement is required beforethe treaty can take effect.
Arizona
Arizona's mining industry rode awave of prosperity during 1988. Itsnonfuel mineral production rose sharplyduring the year to an estimated value of$2.83 billion (Table 2). This representsan increase of more than $1 billion, orabout 58 percent, over the 1987 value.The bulk of this increase is due to thestrong price received during the year forcopper, which accounts for more thanthree-fourths of the State's nonfuel mineral value. The price of copper rosefrom an average of $0.825 per pound in1987 to an average of $1.20 per pound in1988. This price hike was attributed todiminished stocks and strong demand.
Ranking second nationally in thevalue of its nonfuel mineral production,Arizona continues to lead other Statesin the production of copper: in 1988 itproduced nearly two-thirds of the Nation's copper. Copper was recovered at12 principal operations. Copper producers, strengthened by a favorable market,continued to cut costs, expand capacity,and acquire future reserves.
In 1988 Arizona also gained the leadposition in molybdenum production. Insharp contrast to the decline registeredlast year, production was greatly increased in 1988. Arizona's production ofthis coproduct and byproduct metal accounted for almost 50 percent of theNation's domestic supply.
The State retained its place amongthe top producers of bentonite, cement,gem stones, lime, rhenium, sand and
Table 2. Value of nonfuel mineral production in Arizona, measured by mine shipments, sales, or marketable production,including consumption by producers. Allfigures are from the U.S. Bureau of Mines;totals for 1988 are preliminary estimates.
gravel, silver, and sulfuric acid. Mostlead and silver were produced as byproducts of copper or flux ores. Gold production increased 64 percent.
The nonmetallic mineral industry isvery diversified in Arizona. The 1988production value of the largest component, construction sand and gravel,placed Arizona fifth in the Nation forthis commodity. Cement and lime production contributed significantly to thetotal value of industrial minerals, whichexceeded $297 million. There was also aconsiderable increase in the productionof diatomite and salt.
Some 12,000 workers were employedin the Arizona mining industry in 1988.This figure, an increase over 1987,includes workers in the mineral fuelsindustry. About 75 percent of the totalwork force is in copper exploration andproduction.
Most exploration efforts in Arizonafocused on precious metals and leachablecopper. Claim-staking activity remainedmoderately strong during the year; Arizona ranked third among the States inthe number of active claims for all commodities.
Construction began on a tailings recycling facility in Gila County. This
Arizona Geology, vol. 19, no. 2, Summer 1989 3
solvent-extraction/electrowinning (SXEW) plant is designed to wash down apile containing 35 million short tons ofcopper-bearing mill tailings and recoverapproximately 125 million pounds of copper. The $20-million project, the firstof its kind in the United States, willlast about 8 years.
State officials and representatives ofthe mining community attempted to resolve the questions raised by the 1987decision of the State Supreme Court,which declared that Arizona's land-leasing law was unconstitutional. During1988, negotiations were underway between the State Land Commissioner andthree major lessees. These companiesoperate mines on State Trust lands andmake relatively large annual royalty payments to the State. Meanwhile all newapplications for mineral leases were heldin abeyance. Late in the year, the U.S.Supreme Court agreed to hear an appeal.
California
California led the Nation in value ofnonfuel mineral production for the fifthyear in a row. The value of the commodities produced was estimated to be$2.85 billion, a 12 percent increase from1987. California led all States in theproduction of asbestos, boron minerals,portland cement, diatomite, calcinedgypsum, rare-earth metal concentrates,construction sand and gravel, and tungsten ore and concentrates. It was secondin the production of natural calciumchloride, gold, byproduct gypsum, magnesium compounds from seawater, andsodium compounds. Gold exploration inthe State increased as rising productionencouraged further exploration. Severalgold producers continued to expand theiroperations.
No-growth regulations and oppositionto new mining permits impeded miningactivities throughout the State. Goldmining operations, sand-and-gravel quarries, and cement plants were amongthose whose operations were halted ordelayed. Initiatives to prohibit surfacemining operations were proposed in EIDorado, Mariposa, and Tuolomne Counties. Mariposa County narrowly defeatedthis proposal in the fall election. TheState of California, pursuant to AB No.747, now requires that all existing surface-mining operations with vestedrights must have an approved reclamation plan by July 1,1990.
Colorado
The estimated value of nonfuel minerals produced in Colorado in 1988 was$375 million, a O.5-percent decline from1987. Between 1985 and 1988, the reopening of several old precious-metal
4
mines increased Colorado gold output by313 percent. In 1988 gold productionrose 21 percent to an estimated 215,000troy ounces. Silver output at Coloradomines, however, was down an estimated15 percent from 1987. Byproduct leadfrom gold and silver mining decreasednearly 18 percent from that of 1987.
Once again, Denver has become agold capital. More than 50 percent ofU.S. gold production is controlled by thetwo to three dozen companies of local,national, and international standingwhose headquarters or major offices arein or moving to the Denver area.
Exploration continued around the historic mining camps of Creede, CrippleCreek, Leadville, Silverton, and Summitville. Old tailings piles are increasinglybeing considered as sources of metals.
On the Western Slope, seven uranium/vanadium mines were put back intoproduction in 1987-88. Colorado's solenuclear power plant, however, will beshut down before June 30, 1990 becauseof continuing technological problemssince its opening in 1976.
Construction materials for the proposed new Denver airport, beltway E470, and other projects have included anestimated 8 to 12 million short tons offine and coarse aggregates and portlandcement. Portland and masonry-eementproduction and value, however, declinedslightly in 1988. Output of dimensionstone rose an estimated 13 percent, andvalue 7 percent, over 1987.
Crude gypsum production fell 10 percent from that of 1987. The agriculturalcommunity and the U.S. Soil and Conservation Service have been using smallgypsum blocks buried in the soil tomeasure moisture content and reduceground-water pollution, soil erosion, andsalt buildup. Such an inexpensive methodof water conservation is claimed to becapable of raising water availability to alevel higher than that expected fromDenver's proposed Two Forks Dam andReservoir.
The U.S. Congress approved a national charter for the National Mining Hallof Fame and Museum in Leadville, whichwill become a repository of mining artifacts and serve the industry in educatingthe public about mining.
Nevada
Nevada's nonfuel mineral productionwas estimated to be valued at $1.87 billion in 1988, an increase of $420 millionfrom 1987. The increase resulted from a33-percent rise in gold production to 3.6million troy ounces and a 35-percent risein silver production to 16.5 million troyounces. Nevada was the leading State inthe Nation in the production of barite,
gold, mercury, and silver and was thesole producer of mined magnesite. In1988, Nevada ranked third in the UnitedStates in value of nonfuel mineral pro-duction. _
Precious-metal production continued.to increase with at least 10 additionalmine openings. Extensive explorationfor precious metals continued throughoutNevada, focusing on deeper deposits inthe Carlin Trend area in the northwest-ern part of the State. Drilling andexploration projects were conducted inevery county, with important discoveriesreported in Elko, Eureka, Humboldt,Mineral, Nye, and White Pine Counties.
Byproduct production from severalnorthern Nevada gold and silver mineswas a major source of mercury. Nevadafurnished almost all of the Nation'smercury output. The State's barite production continued to decline, with 1988output estimated at 293,000 short tons,Spercent lower than in 1987. Value alsodeclined to $4.2 million, or 12 percentlower than in 1987. Despite the drop inproduction, Nevada remained the leadingbarite-producing State in the Nation.
At the end of August 1988, the U.S.Bureau of Land Management reportedthat 45,948 mining claims had beenreceived in the Nevada office. Employment in the Nevada mining industryreached 11,000 by October 1988, compared to 8,700 in October 1987. By ..Ayearend, the industry had added 2,400~jobs statewide, a 28.2-percent increase.
New Mexico
The value of nonfuel mineral production in New Mexico in 1988 was estimated at a record high of $1.01 billion,a 37-percent increase over 1987. Metalsoutput accounted for more than twothirds of the total value of the State'snonfuel mineral production, with copperbeing the principal contributor.
The State's leading commodities included copper, potash, construction sandand gravel, portland cement, silver, gold,perlite, and crushed stone. Nationally,New Mexico ranked first in productionof perlite and potassium salts and secondin copper, mica, pumice, and silver. Increases were posted for portland cement,copper, gold, lead, perlite, potassiumsalts, pumice, and silver.
The chief reason for the rise in thevalue of nonfuel mineral production wasthe 48-percent increase in the value ofcopper due to higher prices. In contrast,the quantity of copper produced roseonly 2 percent. Another factor in therise in production value was the more ..than 50-percent increase in the quantity .,and value of gold output. Gold prices
(continued on page 12)
Arizona Geology, vol. 19, no. 2, Summer 1989
p
Theses and Dissertations, 1988
(continued on page 12)
fixations: M.S. professional paper, 61p. (RNR)
Elder, A.N., Neutron gauge calibrationmodel for water content of geologicdata: M.S. thesis. (HWR)
Fabryka-Martin, J.T., Production of radionuclides in the earth and their hydrogeologic significance with emphasison chlorine-36 and iodine-129: Ph.D.dissertation, 399 p. (HWR)
Feldman, P.R, Hydrogeology of a contaminated industrial site on filled land:M.S. thesis, 127 p. (HWR)
Goering, T.J., Use of gamma-ray geotomography to measure dry bulk densityand unsaturated flow through tuff:M.S. thesis. (HWR)
Haldeman, W.R, Water flow through variably saturated fractured tuff: A laboratory study: M.S. thesis. (HWR)
Hanson, RT., Aquifer-system compaction,Tucson basin and Avra Valley, Arizona: M.S. thesis. (HWR)
Hartshorne, P.M., Paleoenvironmentalanalysis of a coral-rudist bioherm;Upper Mural Limestone (Lower Cretaceous), southeast Arizona: M.S. prepublication manuscript, 58 p. (G)
Hazlehurst, W.M., An estimation of thewater resources for water planningand management in Fort Valley, Coconino County, Arizona: M.S. thesis, 138p. (HWR)
Jeon, G.J., Innovative methods for longterm mineral forecasting: Ph.D. dissertation, 299 p. (MGE)
Karnieli, Arnon, Storm runoff forecastingmodel incorporating spatial data: PhD.dissertation, 249 p. (RNR)
Kebler, D.G., Coagulation of submicronaluminum hydroxide colloids by silicaparticles: M.S. thesis, 198 p. (HWR)
Lapham, W.W., Conductive and convective heat transfer in sediments nearstreams: Ph.D. dissertation, 318 p.(HWR)
Law, KJ., Dissolution of lead smelterdust compounds by humic acid: M.S.thesis, 30 p. (G)
Lawson, P.W., Sorption of fulvic acid onaluminum oxide and desert soil: M.S.thesis. (HWR)
Leo, T.P., Computer studies of heattracer experiments in fractured rock:M.S. thesis. (HWR)
MacInnes, S.c., Lateral effects in controlled source < audiomagnetotelurics:Ph.D. dissertation, 188 p. (G)
Maus, D.A., Ore controls at the GoldenRule mine, Cochise County, Arizona:M.S. thesis, 114 p. (G)
Page, D.I., Overland flow partitioning forrill and interrill erosion modeling: M.S.
perspective ofwind regimes, and
Muehlberger, E.W., The structure andgeneral stratigraphy of the westernhalf of the Payson basin, Gila County,Arizona: M.S. thesis, 86 p.
Shirley, DH., Geochemical facies analysisof the Surprise Canyon Formation inFern Glen channelway, central GrandCanyon, Arizona: M.S. thesis, 240 p.
Waters, J.P., A geophysical and geochemical investigation of selected collapsefeatures on the Coconino Plateau innorthern Arizona: M.S. thesis, 112 p.
University of Arizona
Akman, H.H., Resistivity and induced polarization responses over two differentearth geometries: M.S. thesis, 109 p.(G)
Asmerom, Yemane, Mesozoic igneous activity in the southern Cordillera ofNorth America; implication for tectonics and magma genesis: Ph.D. dissertation, 232 p. (G)
Aubele, Jane, Crumpeler, J.S., andElston, W.E., Vesicle zonation and vertical structure of basalt flows: M.S.thesis, 59 p. (PS)
Beer, KE., A ground-water study andpredictive model for the town of Florence, Arizona: M.S. thesis, 105 p.(HWR)
Brooks, S.J., A multidisciplinary analysisof the hydrogeology of the MaricopaSuperconducting Super Collider (SSC)site, Maricopa County, Arizona: M.S.thesis, 85 p. (HWR)
Byrne, RW., Ridge-transform-ride dynamics: M.S. prepublication manuscript,23 p. (G)
Calderone, G.J., Paleomagnetism of Miocene volcanic rocks in the MojaveSonora Desert region, Arizona andCalifornia: Ph.D. dissertation, 163 p.(G)
Chen, Chuangming, Andisols of the SanFrancisco volcanic field, Arizona: M.S.thesis, 111 p. (SWS)
Chuang, Yuen, Solute transport measurement by ion-selective electrodes infractured tuff: M.S. thesis. (HWR)
Identification of an opgrc:Julld1water management strate
contaminated aquifer: M.S.
DClle~~ovl'skj, J.R., The hydrogeochemistryin the Ranegras Plain
gI'()til1ld\'lrah~rbasin: M.S. thesis. (HWR)Paleomagnetim of the
Implications forAmerican apparentM.S. prepublication
Northern Arizona Urliv1ersity
Darrach, M.E., A kinematic and l1:el:Jmletric structural analysis on anProterozoic crustal-scale shearthe evolution of the Shylockzone, central Arizona: M.S.78p.
Johns, M.E., Architectural element,_ sis and depositional history• Upper Petrified Forest Member
Chinle Formation, PetrifiedNational Park, Arizona: M.S.163 p.
Doorn, S.S., Theoretical energetics ofthe formation of iron-nickel alloyand magnetite in olivine: M.S. thesis,116 p. (Gl)
Evans, KE., Distribution of hourly rainfall intensities in the southwest UnitedStates summer monsoon: M.A. thesis,80 p. (Gg)
Schuver, H.J., Modeling volcano morphology: M.S. thesis, 120 p. (Gl)
Arizona State University
Arizona State University, Tempe, AZ85287; (602) 965-9011. (Gg-Geography;GI-Geology)
Northern Arizona University, Flagstaff,AZ 86011; (602) 523-9011.
eJniVerSity of Arizona, Tucson, AZ 85721;(602) 621-2211. (G-Geosciences; HWRHydrology and Water Resources; MGEMining and Geological Engineering;PS-Planetary Sciences; RNR-RenewableNatural Resources; SWS-Soil and WaterScience)
e The following list includes theses anddissertations on Arizona geology, geological engineering, hydrology, and relatedsubjects that were awarded in 1988 byArizona State University, Northern Arizona University, and the University ofArizona. This list, however, is not acomplete compilation of theses on suchtopics. Theses on the geology of otherStates that were awarded by these universities are not listed, nor are theseson the geology of Arizona that wereawarded by out-of-State universities.
Most theses included here are notavailable in the library of the ArizonaGeological Survey. Each thesis, however,may be examined at the main library ofthe university that awarded it. Information may also be obtained from therespective departments, which are indicated in parentheses after each citationusing the codes listed below. (Thesesfrom Northern Arizona University wereawarded by the geology department.)
Arizona Geology, vol. 19, no. 2, 5
Figure 2 (right). Simplified geologic map ofthe Buckskin and Rawhide Mountains showing the location of important mines and geographic features.· The Buckskin Mountainsinclude all areas of bedrock south of the BillWilliams River and east of the ColoradoRiver, unless otherwise labeled (modified fromSpencer, 1989).
(continued from page 1)
for other areas in western North America, Spain, and New Guinea. The recentlydiscovered Copperstone mine, Arizona'slargest gold producer with annual production at approximately 60,000 ounces,is now known to be a detachment-faultrelated deposit (Spencer and others,1988). Recent recognition of thesedeposits as a distinct deposit type andtheir association with metamorphic corecomplexes, which are themselves recentlyrecognized and incompletely understoodfeatures, have sparked much scientificinterest. Discovery of the Copperstonemine has also generated explorationinterest in these deposits. The largestdomestic deposits of manganese, a strategic and critical mineral, are present inthe Artillery Mountains, which are adjacent to the Buckskin and RawhideMountains, and may have originated byprocesses associated with detachmentfaulting. Because of these geologic andmineral-resource attributes, the Buckskinand Rawhide Mountains have attractedconsiderable attention from geologistsduring the past 15 years, beginning withthe pioneering PhD. study of the geology of the Rawhide Mountains by TerryShackelford (Shackelford, 1976, 1989a,b;Davis, G.A., 1989).
+
LOWER-PLATE UNITS
MYLONITIC CRYSTALLINE ROCKS (TERTIARY TO PROTEROZOIC)
CACTUS
11
i
114° 00'
eHarcuvar metamorphic core complex,which includes the Buckskin and Rawhide Mountains, is one of the approx-
5
5
P L A I N
l:o':o:~o;:::1 SEDIMENTARY ROCKS (MIDDLE TO LATE MIOCENE)
POSTDETACHMENT DEPOSITS
C=:J SURFICIAL DEPOSITS (QUATERNARY TO LATEST TERTIARY)
~ BASALT AND LOCAL INTERMEDIATE TO SILICIC VOLCANIC ROCKS AND SEDIMENTARY~ ROCKS, FLAT-LYING TO GENTLY TILTED (MIDDLE TO LATE MIOCENE)
I~ MYLONITIC METASEDIMENTARY ROCKS (MESOZOIC TO PALEOZOIC)
!!2° Mi. 0! I
L34°00'
km 0
.variably mylonitic f~twall rocks alonglarge-displacement, Tertiary low-anglenormal faults (detachment faults). The
The Buckskin and Rawhide Mountainsare within the Basin and Range physiographic province of southwestern NorthAmerica. This province, which includessouthern and western Arizona, is characterized by numerous mountain rangesand intervening Cenozoic basins. Thephysiography of the Basin and RangeProvince is largely the product of middleand late Cenozoic low- and high-anglenormal faulting, volcanism, and erosion.The significance and'l'elative age of eachof these processes vary greatly fromrange to range. Miocene low-angle normal faulting was the dominant processthat determined the physiography of theBuckskin and Rawhide Mountains. Younger basaltic volcanism, erosion, andminor, postdetachment high-angle faulting were also important.
Cordilleran metamorphic core complexes are typically characterized bynormal-faulted and extended hangingwall rocks that overlie well-lineated,
Geology
6 Arizona Geology, vol. 19, no. 2, Summer 1989
0'·
l~+ -r "
8 U T L E R V A L L E Y
core complexes have been intensivelystudied during the Pilst 15 years. Theseonce enigmatic associations of rocks andstructures are now generally recognized
UPPER-PLATE UNITS
SEDIMENTARY AND VOLCANIC ROCKS, GENERALLYMODERATELY TO STEEPLY DIPPING (LATEOLIGOCENE TO MIDDLE MIOCENE)
METAVOLCANIC AND METASEDIMENTARY ROCKS(MESOZOIC)
METASEDIMENTARY ROCKS (PALEOZOIC)
CRYSTALLINE ROCKS (LARGELY PROTEROZOIC,LOCALLY TERTIARY AND MESOZOIC)
\&ately 10 such complexes that are discontinuously exposed in a belt extendingdiagonally across Arizona into southeastern California (Figure 1). Metamorphic
Arizona Geology, vol. 19, no. 2, Summer 1989
..Jl.-Il- ,"
J.--l.- ...
..J-...
--'"...........
SYMBOLS
BUCKSKIN-RAWHIDE DETACHMENT FAULT
LOW-ANGLE NORMAL FAULT
HIGH-ANGLE NORMAL FAULT
HIGH-ANGLE FAULT
THRUST OR REVERSE FAULT
ALL FAULTS DASHED WHERE APPROXIMATELYLOCATED OR INFERRED, DOTTED WHERE CONCEALED.
as products of large-magnitude displacement on moderately to gently dippingnormal faults and their down-dip continuations as ductile shear zones.
7
Figure 3. Schematic structure-stratigraphy diagram for the Buckskin and, Rawhide Mountainsshowing all important pre-Pliocene rock types and some of their contact relationships.Movement on rotational normal faults (not shown) caused tilting of upper-plate rocks.
Mineralization and Alteration
Mineral deposits are widely distributed in the Buckskin and Rawhide Mountains and, with a few notable exceptions,are along or within a few tens of metersof the detachment fault (Figure 6).Most of the depositS contain massive orfracture-filling specular hematite andyounger fracture-filling chrysocolla.Early-formed copper and iron sulfideswere probably common, but are largelyobscured by later oxidation. Hydrothermal-carbonate replacements are alsopresent along the fault and are common-ly associated with copper-iron mineraldeposits. These deposits have yieldedapproximately 52 million pounds of copper and 15,500 ounces of gold, withminor amounts of lead, zinc, and silver(Keith and others, 1983). All of the'.'deposits formed at the same time tha:detachment faulting and related structural and sedimentary phenomenaoccurred. They are believed to have
from beneath a wedge of brittlelyextending upper-plate rocks, and wereoverprinted successively by chloriticalteration and brecciation, microbreccJ'iation, and fault-gouge formation along .narrow fault zone (Wernicke, 1981, 19 ;Davis, G.B., 1983; Reynolds, 1985; Davis,G.A., and others, 1986). Arching andsubareal exposure of the lower plate ledto shedding of mylonitic debris into syntectonic sedimentary basins and to thedistinctive physiography of many of thecomplexes (Rehrig and Reynolds, 1980;Howard and others, 1982; Spencer, 1984;Pain, 1985; Miller and John, 1988; Spencer and others, 1989a).
Upper-plate rocks in the Buckskinand Rawhide Mountains contain abundant evidence of compressional deformation and metamorphism of Mesozoic andPaleozoic sedimentary rocks. The stratigraphy of the pre-Tertiary rocks isrecognizable in spite of variable buttypically severe deformation and greenschist-grade metamorphism (Reynoldsand others, 1987, 1989; Reynolds andSpencer, 1989; Spencer and others,1989b). Deformation occurred in association with generally south-directed, lateMesozoic thrust faulting within the eastwest-trending Maria fold-and-thrust belt(Reynolds and others, 1986).
Detachment faulting and relateddeformation and sedimentation were fO~.1
lowed by dominantly basaltic volcanis~
with local associated felsic volcanism .(Suneson and Lucchitta, 1983). Trachyteflows and interbedded pyroclastic rocksin the western Buckskin Mountains arethe same age as, and may have evolvedfrom, magmas associated with adjacentpostdetachment basalts (Grubensky,1989).
(Davis, G.A., and others, 1986; Davis,G.A., and Lister, 1988; Marshak andVander Muelen, 1989; Spencer and Reynolds,1989b).
The detachment fault forms a corrugated surface defined by east-northeast-trending antiforms and synforms(Figure 4). Lower-plate foliation andlithologic layering broadly conform tothe form of the detachment fault, atleast in areas where exposure throughthe lower plate is good, such as theeast face of Planet Peak and the westface of Ives Peak (Figure 2). The originof these corrugations is unknown, butthey are suspected to be related todetachment faulting and mylonitizationbecause the direction of displacement onthe detachment fault and mylonitic lineation are approximately parallel to antiform and synform axes.
Except for the corrugations, all ofthe basic Tertiary structural features inthe Buckskin and Rawhide Mountains,and in metamophic core complexes ingeneral, are accounted for by the shearzone model. This model envisions thateach metamorphic core complex originated by large displacement on a masterlow-angle normal fault that extendeddown dip into a zone of mylonitization(Figure 5). According to this model,rocks originally mylonitized at perhaps8- to IS-kilometer depth rose isostatically and cooled as they were displaced
THRUST FAULT
REPLACEMENT CARBONATE
CHLORITIC BRECCIA
CARBONATE AND CALC-Sill CATESLIVER
"""f---VARIABLY MYLONITIC CRYSTALUNEROCKS
The subhorizontal Buckskin-Rawhidedetachment fault is exposed discontinuously throughout the Buckskin andRawhide Mountains (Figure 2). Hangingwall rocks, collectively referred to asthe upper plate, consist of a variety ofcomplexly normal-faulted and tiltedrocks that include syntectonic, midTertiary sedimentary and volcanic rocksand variably deformed and metamorphosed, Mesozoic and Paleozoic sedimentary and volcanic rocks (Figure 3). Thefootwall block, commonly referred to asthe lower plate (platelike form is notimplied), is composed of variably mylonitic crystalline and metasedimentaryrocks and is thought to be structurallycontinuous with similar lower-plate rocksin the nearby Harcuvar and WhippleMountains. The mid-Tertiary age ofsome of the mylonitized rocks in theWhipple, Buckskin, and Rawhide Mountains has recently been established byU-Ph (zircon) geochronologic study(Wright and others, 1986; Bryant andWooden, 1989). A northeastward direction of displacement of upper-plate rocksrelative to the lower plate is inferredbased on a number of criteria (e.g.,Davis, G.A., and others, 1980; Reynoldsand Spencer, 1985; Howard and John,1987). The sense of displacement on thedetachment fault is the same as thatindicated for mylonitization by asymmetric petrofabrics in the mylonites
Arizona Geology, vol. 19, no. 2, Summer 1989
N ]
134°00'
KM 0 5 10 15 20I I !
I 'I 'i I
MI 0 5 \0
113°30' o QUATERNARY SURFICIAL DEPOSITS
UPPER-PLATE ROCKS
LOWER-PLATE ROCKS, WITHCONTOURS SHOWING MINIMUMELEVATION OF DETACHMENTFAULT IN METERS
HIGH-ANGLE FAULT,DASHED WHERE APPROXIMATE ORINFERRED, DOTTED WHERECONCEALED
Figure 4 (above). Minimum-relief contour map of the Buckskin-Rawhide detachment fault.
9
formed from aqueous brines that leachedmetals from strata within extensionalsedimentary basins (Wilkins and Heidrick, 1982; Spencer and Welty, 1986,1989; Wilkins and others, 1986; Lehmanand Spencer, 1989). The recent discovery of the Copperstone deposit in westcentral Arizona, which is estimated tocontain more than 500,000 ounces ofgold and is related to the Moon Mountains detachment fault, has led torenewed interest in detachment-faultrelated mineral deposits (Spencer andothers, 1988).
Manganese deposits hosted in upperplate, Miocene sedimentary rocks in theBuckskin and Rawhide Mountains haveyielded approximately 24 million poundsof manganese. Similar manganese deposits in the nearby Artillery Mountains arethe largest of such deposits in theUnited States (Lasky and Webber, 1949).Some of the deposits in the ArtilleryMountains are younger than previouslysuspected and may postdate detachmentfaulting and related mid-Tertiary tectonism. These younger deposits formedfrom low-salinity fluids and thus werenot derived directly from the salineaqueous fluids that caused detachmentfault-related mineralization (Spencer andothers, 1989a).
Figure 5 (left), Cross-section evolution diagram of Miocene extension in the Buckskinand Rawhide Mountains.
10090o7060o KM
~BREAKAWAY5
15
B 10
Arizona Geology, vol. 19, no. 2,
BREAKAWAY
A : -l:1ik>-·.·.. ::J::,::~;:,~'i·:,~·;f3)~·,~i;.;::.:·;;,,~:.:..;;:··;;,,· ~~I:NC:,P:1E~NT~M~'~CO~N:1T1Z:'T:,O~~;~;~~~~~~·
-D
Conclusion
Selected References
Rawhide Mountains present an exceptional opportunity to improve basicgeologic understanding.
Although Bulletin 198 represents amajor step forward in deciphering thltcomplex geologic evolution of a majorCordilleran metamorphic core complex, itis clear that many questions remain unanswered. One can only hope that futureinvestigators find these problems interesting and tractable and that the momentum established since Terry Shackelford's pivitol dissertation will continueto advance the geologic understanding ofthis remarkable area.
Brooks, W.E., 1986, Distribution of anomalouslyhigh K20 volcanic rocks in Arizona: Metasomatism at the Picacho Peak detachmentfault: Geology, v. 14, p. 339-342.
__ 1988, Recognition and geologic implicationsof potassium metasomatism in upper-platevolcanic rocks at the detachment fault at theHarcuvar Mountains, Yavapai County, Arizona: U.S. Geological Survey Open-File Report88-17,9 p.
Bryant, Bruce, and Wooden, J.1., 1989, Lowerplate rocks of the Buckskin Mountains, Arizona: A progress report, in Spencer, J.E., andReynolds, S.J., eds., Geology and mineralresources of the Buckskin and Rawhide Mountains, west-cen tral Arizona: Arizona Geological Survey Bulletin 198, p. 47-50.
Davis, G.A., 1989, Terry Shackelford and the Raw-hide Mountains: A retrospective view, inSpencer, J.E., and Reynolds, S.J., eds., Geoi.ogy and mineral resources of the BuckskiIllllJand Rawhide Mountains, west-central Arizo-na: Arizona Geological Survey Bulletin 198,p.11-14.
Davis, G.A., Anderson, J.1., Frost, E.G., andShackelford, T.J., 1980, Mylonitization anddetachment faulting in the Whipple-BuckskinRawhide Mountains terrane, southeasternCalifornia and western Arizona, in Crittenden,M.D., Jr., and others, eds., Cordilleran metamorphic core complexes: Geological Societyof America Memoir 153, p. 79-129.
Davis, G.A., and Lister, G.S., 1988, Detachmentfaulting in continental extension; perspectivesfrom the southwestern U.S. Cordillera, inClark, S.P., Jr., and others, eds., Processes incontinental lithospheric deformation: Geological Society of America Special Paper 218, p.133-160.
Davis, G.A., Lister, G.S., and Reynolds, S.J., 1986,Structural evolution of the Whipple and SouthMountains shear zones, southwestern UnitedStates: Geology, v. 14, p. 7-10.
Davis, G.H., 1983, Shear-zone model for the originof metamorphic core complexes: Geology, v.11, p. 342-347.
Grubensky, M.J., 1989, Geology of postdetachment, Miocene volcanic rocks in the southwestern Buckskin Mountains, in Spencer, J.E.,and Reynolds, S.J., eds., Geology and mineralresources of the Buckskin and Rawhide Mountains, west-cen tral Arizona: Arizona Geological Survey Bulletin 198, p. 255-262.
Halfkenny, R.D., Jr., Kerrich, Robert, and Rehrig,W.A., 1989, Fluid regimes and geochemicalmass transport in the development of mylon-ites and chloritic breccias at Copper Penney,Buckskin Mountains, in Spencer, J.E., andReynolds, S.J., eds., Geology and mineral rl'.sources of the Buckskin and Rawhide Moun'Wtains, west-central Arizona: Arizona Geological Survey Bulletin 198, p. 190-202.
Howard, K.A., and John, B.E., 1987, Crustal extension along a rooted system of imbricate low-
BASALT
SANDSTONE AND CONGLOMERATE
VOLCANIC FLOWS AND TUFFS
LIMESTONE/MARBLE
SEDIMENTARY BRECCIA
HYDROTHERMAL CARBONATE
GRANITIC ROCKS
CHLORITIC BRECCIA
MYLONITIC CRYSTALLINE ROCKS
~.+.....I + + + ~
f777'~II;r/ 1,!I\j~
IA ",AA All LI ill
...!,:,c::,':/
Figure 6. Sites of mineralization during detachment faulting.
Better understanding of the genesisof metamorphic core complexes, theirrelationship to older tectonic features,and their associated mineral deposits andigneous rocks could elucidate the natureof general processes that occur inextensional tectonic settings, includingthose related to the genesis of economicmineral deposits. The remarkably wellexposed and well-developed compressional and extensional structures andmineral deposits in the Buckskin and
calcite and iron-manganese-oxide veinemplacement (Reynolds and Lister, 1987;Halfkenny and others, 1989).
The abundant evidence for widespread mid-Tertiary mineralization andalteration suggests that complex chemicaland physical processes operated on ascale at least as large as the metamorphic core complex itelf. Genetic relationships between copper + iron ± goldmineralization and carbonate metasomatism along detachment faults, and Kmetasomatism and manganese mineralization in the upper plate, have not beenestablished. All, however, were producedapproximately synchronously in the sametectonic environment and are remarkablywell developed in the Buckskin andRawhide Mountains.
Figure 7. Setting and types ofmineralization and alteration during extension.
In addition to manganese and detachment-fault-related mineralization,widespread potassium metasomatism ofupper-plate rocks and chloritic alterationof brecciated rocks below the detachment fault attest to the pervasiveness ofaqueous geochemical activity duringdetachment faulting (Figure 7). K metasomatism has been recognized elsewherein association with detachment faults(Brooks, 1986, 1988) and is known to beolder than detachment-fault-relatedmineralization in the eastern HarcuvarMountains (Roddy and others, 1988). Kmetasomatism in the Buckskin Mountainshas largely converted mafic volcanicflows, which may have originally beenalkalic, to K-feldspar, calcite, and ironand manganese oxides (Kerrich andothers, 1989). Plagioclase in K-metasomatized, upper-plate basalt flows in theBuckskin Mountains has been largely orentirely converted to K-feldspar; numerous K-Ar dates of feldspar concentratesfrom these rocks reveal a mid-Mioceneage of K metasomatism (Spencer andothers, 1989c). Chloritic alteration oflower-plate rocks, involving massiveaddition of iron, manganese, and magnesium and loss of silica, sodium, andpotassium, occurred in a different fluidregime than that associated with later
Arizona Geology, vol. 19, no. 2, Summer 1989
angle faults: Colorado River extensional corridor, California and Arizona, in Coward, M.P., and others, eds., Continental extensionaltectonics: GeQlogical Society of London Special Publication 28, p. 299-311.
~10ward, K.A., Stone, Paul, Pernokas, M.A., and'WI' Marvin, RF., 1982, Geologic and geochrono
logic reconnaissance of the Turtle Mountainsarea, California, west border of the WhippleMountains detachment terrane, in Frost, E.G.,and Martin, D.L., eds., Mesozoic-Cenozoic tectonic evolution of the Colorado River region,California, Arizona, and Nevada: San Diego,Cordilleran Publishers, p. 341-354.
Keith, S.B., Gest, D.E., DeWitt, Ed, Woode Toll,Netta, and Everson, B.A., 1983, Metallic mineral districts and production in Arizona:Arizona Bureau of Geology and Mineral Technology Bulletin 194,58 p.
Kerrich, Robert, Rehrig, W.A., and McLarty, Elisabeth, 1989, Volcanic rocks in the suprastructureof metamorphic core complexes, southwestArizona: Geochemical and isotopic evidencefor primary magma types and secondaryhydrothermal regimes, in Spencer, J.E., andReynolds, S.J., eds., Geology and mineralresources of the Buckskin and Rawhide Mountains, west-central Arizona: Arizona Geological Survey Bulletin 198, p. 203-214.
Lasky, S.G., and Webber, B.N., 1949, Manganeseresources of the Artillery Mountains region,Mohave County, Arizona: U.S. GeologicalSurvey Bulletin 961, 86 p.
Lehman, N.E., and Spencer, J.E., 1989, Mineralization in the central part of the Planet mineraldistrict, northwestern Buckskin Mountains, inSpencer, J.E., and Reynolds, S.J., eds., Geologyand mineral resources of the Buckskin andRawhide Mountains, west-central Arizona:Arizona Geological Survey Bulletin 198, p. 215222.
Marshak, Stephen, and Vander Meulen, Marc,1989, Geology of the Battleship Peak area,a southern Buckskin Mountains, Arizona: Struc
.. fturall ~tyle belowJ
Ethe Bduckskin detachmentau t, In Spencer, .., an Reynolds, S.J., eds.,
Geology and mineral resources of the Buckskin and Rawhide Mountains, west-centralArizona: Arizona Geological Survey Bulletin198, p. 51-66.
Miller, J.M.G., and John, RE., 1988, Detachedstrata in a Tertiary low-angle normal faultterrane, southeastern California: A sedimentary record of unroofing, breaching, arid continued slip: Geology, v. 16, p. 645-648.
Pain, e.F., 1985, Cordilleran metamorphicicor~
complexes in Arizona: A contribution fromgeomorphology: Geology, v. 13, p. 871-874.
Rehrig, W.A., and Reynolds, S.J., 1980, Geologicand geochronologic reconnaissance of a n()~th
west-trending zone of metamorphic core.c0Ilt-.plexes in southern and western Arizona,inCrittenden, M.D., Jr., and others, eds.,Co~
dilleran metamorphic core complexes: Geological Society of America Memoir 153, p.131-157.
Reynolds, S.J., 1980, A conceptual basisfortlt~
occurrence of uranium in Cordilleran meta"morphic core complexes, in Coney, P.J.,/aI\d.Reynolds, S.J., eds., Cordilleran metarllOrphiccore complexes and their uranium favor~bilit}',
with contributions by G.H. Davis and0tl\~rs:
gj~x?~~~~';\~~_~l;;~rgy open-Filei~eI"'rt__ 1985, Geology of the South Mountaills,cell"
~~~:c~z~~ca~n~~;yn~J~~:~9~: ~e;J°g}'S~i0Reynolds, S.J., and Lister, G.S., 1987,Stnlct11Tal
:~:~~o:;s:fl~~~O;;' :~~:;.t~~~~.dE!t~c0·Reynolds, S.J., and Spencer, J.E., 1985, EVi~e
for large-scale transport on the Bullar~d~t~clt"
at ~~;~ ~fis~est-centralArizona: GeOl~g}'!8"
~ 1989, Pre-Tertiary rocks and struc.t11Tes:illthe upper plate of the Buckskin detaslt.Iltl!lltfault, west-central Arizona, in Spencer~l.·and Reynolds, S.J., eds., Geology andl1un~
resources of the Buckskin and RawhideMo
Arizona Geology, vol. 19, no. 2, Summer 198~
tains, west-central Arizona: Arizona Geological Survey Bulletin 198, p. 67-102.
Reynolds, S.J., Spencer, J.E., Asmerom, Yemane,DeWitt, Ed, and Laubach, S.E., 1989, EarlyMesozoic uplift in west-central Arizona andsoutheastern California: Geology, v. 17, p.207-211.
Reynolds, S.J., Spencer, J.E., and DeWitt, Ed, 1987,Stratigraphy and U-Th-Pb geochronology ofTriassic and Jurassic rocks in west-central Arizona, in Dickinson, W.R, and Klute, M.A.,eds., Mesozoic rocks of southern Arizona andadjacent areas: Arizona Geological SocietyDigest, v. 18, p. 65-80.
Reynolds, S.J., Spencer, J.E., Richard, S.M., andLaubach, S.E., 1986, Mesozoic structures inwest-central Arizona, in Beatty, Barbara, andWilkinson, P.A.K., eds., Frontiers in geologyand ore deposits of Arizona and the Southwest: Arizona Geological Society Digest, v. 16,p.35-51.
Roddy, M.S., Reynolds, S.J., Smith, RM., andRuiz, Joaquin, 1988, K-metasomatism anddetachment-related mineralization, HarcuvarMountains, Arizona: Geological Society ofAmerica Bulletin, v. 100, p. 1627-1639.
Shackelford, T.J., 1976, Structural geology of theRawhide Mountains, Mohave County, Arizona: Los Angeles, University of Southern California, unpublished Ph.D. dissertation, 176 p.
1989a, Geologic map of the Rawhide Mountains, Mohave County, Arizona, in Spencer, J.E., and Reynolds, S.J., eds., Geology and mineral resources of the Buckskin and RawhideMountains, west-central Arizona: ArizonaGeological Survey Bulletin 198, scale 1:42,850.
1989b, Structural geology of the RawhideMountains, Mohave County, Arizona, in Spencer, J.E., and Reynolds, S.J., eds., Geology andmineral resources of the Buckskin and Rawhide Mountains, west-central Arizona: Arizona Geological Survey Bulletin 198, p. 15-46.
Spencer, J.E., 1984, Role of tectonic denudation inwarping and uplift of low-angle normal faults:Geology, v. 12, p. 95-98.
1989, Compilation geologic map of the Buck. and Rawhide Mountains, west-centralrizona, in Spencer, J.E., and Reynolds,S.].,
eds., Geology and mineral resources of theBuckskin and Rawhide Mountains, west-entral Arizona: Arizona Geological Survey
letin 198; scale 1:100,000.J.E., Duncan, J.T., and Burton, W.D.,he Copperstone mine: Arizona's new
gold producer: Arizona Bureau of Geologyand Mineral Technology Fieldnotes, v. 18, no.2, p. 1-3.
Spencer, J.E., Grubensky, M.J., Duncan, J.T.,Shenk, J.D., Yamold, J.e., and Lombard, J.P.,1989a, Geology and mineral deposits of thecentral Artillery Mountains, in Spencer, J.E.,and Reynolds, S.J., eds., Geology and mineralresources of the Buckskin and Rawhide Mountains, west-central Arizona: Arizona Geological Survey Bulletin 198, p. 168-183.
Spencer, J.E., and Reynolds, S.J., 1989a, Introduction to the geology and mineral resourcesof the Buckskin and Rawhide Mountains,in Spencer, J.E., and Reynolds, S.J., eds., Geology and mineral resources of the Buckskinand Rawhide Mountains, west-central Arizona: Arizona Geological Survey Bulletin 198, p.1-10.
__ 1989b, Tertiary structure, stratigraphy, andtectonics of the Buckskin Mountains, in Spencer, J.E., and Reynolds, S.J., eds., Geology andmineral resources of the Buckskin and Rawhide Mountains, west-central Arizona: ArizonaGeological Survey Bulletin 198, p. 103-167.
Spencer, J.E., Reynolds, S.J., and Lehman, N.E.,1989b, Geologic map of the Planet-Mineral Hillarea, northwestern Buckskin Mountains, westcentral Arizona, in Spencer, J.E., and Reynolds,S.J., eds., Geology and mineral resources of theBuckskin and Rawhide Mountains, westcentral Arizona: Arizona Geological SurveyBulletin 198, scale 1:24,000.
Spencer, J.E., Shafiqullah, M., Miller, RJ., andPickthorn, L.G., 1989c, K-Ar geochronology ofMiocene extension, volcanism, and potassiummetasomatism in the Buckskin and RawhideMountains, in Spencer, J.E., and Reynolds, S.J.,eds., Geology and mineral resources of theBuckskin and Rawhide Mountains, westcentral Arizona: Arizona Geological SurveyBulletin 198, p. 184-189.
Spencer, J.E., and Welty, J.W., 1986, Possiblecontrols of base- and precious-metal mineralization associated with Tertiary detachmentfaults in the lower Colorado River trough,Arizona and California: Geology, v. 14, p.195-198.
__ 1989, Geology of mineral deposits in theBuckskin and Rawhide Mountains, in Spencer,J.E., and Reynolds, S.J., eds., Geology andmineral resources of the Buckskin and Rawhide Mountains, west-central Arizona: Arizona Geological Survey Bulletin 198, p. 223-254.
Suneson, N.H., and Lucchitta, Ivo, 1983, Origin ofbimodal volcanism, southern Basin and RangeProvince, west-central Arizona: GeologicalSociety of America Bulletin, v. 94, p. 1005-1019.
Wernicke, Brian, 1981, Low-angle normal faults inthe Basin and Range Province: Nappe tectonics in an extending orogen: Nature, v. 291, p.645-648.
__ 1985, Uniform-sense normal simple shear ofthe continental lithosphere: Canadian Journalof Earth Sciences, v. 22, p. 108-125.
Wilkins, Joe, Jr., Beane, RE., and Heidrick, T.L.,1986, Mineralization related to detachmentfaults: A model, in Beatty, Barbara, and Wilkinson, P.A.K., eds., Frontiers in geology andore deposits of Arizona and the Southwest:Arizona Geological Society Digest, v. 16, p.108-117.
Wilkins, Joe, Jr., and Heidrick, T.L., 1982, Baseand precious metal mineralization related tolow-angle tectonic features in the WhippleMountains, California and Buckskin Mountains, Arizona, in Fiost, E.G., and Martin, D.L., eds., Mesozoic-Cenozoic tectonic evolutionof the Colorado River region, California, Arizona, and Nevada: San Diego, CordilleranPublishers, p. 182-203.
Wright, J.E., Anderson, J.L., and Davis, G.A.,1986, Timing of plutonism, mylonitization, anddecompression in a metamorphic core complex, Whipple Mountains, CA [abs.]: Geological Society of America Abstracts withPrograms, v. 18, p. 201.
11
(continued from page 4)
remained high, even though the averageprice slipped· from $448 per troy ouncein 1987 to an estimated $439 in 1988.Although silver production rose nearly30 percent in quantity, lower pricesbrought a slump in value. No molybdenum production was reported in 1988.
After several years of depressedprices in the potash industry, productionstabilized and its value rose more than46 percent. New Mexico producersclaimed that dumping by Canadian producers had forced U.S. prices down,and in 1987 two companies filed an antidumping petition with the U.S. International Trade Commission. Early in January 1988, Canadian potash producersagreed to sell their product to U.S.farmers at a fair-market value and
thereby avoid a final decision by thecommission to impose heavy duties onthe industry. As a result, New Mexico'spotash industry improved throughout theyear. Although several mines changedownership, others started up and oneannounced an expansion.
Utah
The value of nonfuel mineral production in Utah in 1988 increased 41 percent over that of 1987 and reached arecord high of $990 million. Productionexceeded the previous record achieved in1981 when copper output peaked. Metalsaccounted for about four-fifths of thevalue of nonfuel mineral production,with copper, gold, and magnesium theprincipal contributors. Leading commod-
ities included copper, gold, magnesium,portland cement, construction sand andgravel, salt, silver, crushed stone,phosphate, and potash.
The rise in the value of nonfuel mitAeral production was directly attribut~.to high prices for copper and gold andincreased output at a recently reopenedcopper mine. Although silver output increased, lower prices brought a slumpin value. Molybdenum production declined in quantity and value as pricesand demand continued to slip. Anincrease in magnesium output also contributed to the rise in metal production.The declines posted for constructionmaterials such as portland cement, gypsum, construction sand and gravel, andcrushed stone were related, in part, to adepressed construction industry and theshutdown of several operations.
,..---- Arizona Geology---~
Arizona Geological Survey
Director & State Geologist: Larry D. FellowsEditor: Evelyn M. VandenDolderEditorial Assistant: Nancy SchmidtIllustrators: Peter F. Corrao, Sherry F. Gamer
Wayne, R.F., The effect of bank protection on infiltration losses in the SantaCruz River, Arizona: M.S. thesis (HWR)
Welty, J.W., Strontium isotopic compositions of igneous rocks at the SanManuel-Kalamazoo porphyry copperdeposit, Pinal County, Arizona: M.s.prepublication manuscript, 27 p. (G)
Yiannakakis, A.E., Adsorption/desorption of phenols on the Pima clay loamsoil: M.S. thesis, 100 p. (SWS)
Young, D.P., The history of deformatio;iia.and fluid phenomenon in the top~the Wilderness Suite, Santa CatalinaMountains, Pima County, Arizona: M.S.thesis, 144 p. (G)
(continued from page 5)
thesis, 112 p. (RNR)Porcello, J.J., Pre-development hydrologic
conditions of the Salt River IndianReservation, east Salt River Valley,central Arizona, with an emphasis onthe ground-water flow regime: M.S.thesis. (HWR)
Rasmussen, T.e., Fluid flow and solutetransport through three-dimensionalnetworks of variably saturated discretefractures: Ph.D. dissertation, 327 p.(HWR)
Reed, P.E., Jr., A variable moduli probabilistic constitutive model for soils:M.S. thesis, 103 p. (MGE)
Rogoff, E.B., Characterization of waterinteraction with the Apache Leap Tuff,Superior, Arizona, using stable isotopesof oxygen and hydrogen: M.S. thesis,162 p. (HWR)
Scovill, G.L., Tailing pond seepage andsulfate equilibrium in the Pima miningdistrict, Pima County, Arizona: M.S.thesis, 78 p. (HWR)
Seidemann, R.H., Gaseous transport inthe vadose zone; computer simulationsusing the discrete state compartmentmodel: M.S. thesis, 82 p. (HWR)
Smith, B.D., The distribution of radon222 in the ground water of the northcentral Tucson basin and its relationship to the hydrogeology: M.S. thesis.(HWR)
Tidwell, V.e., Determination of theequivalent saturated hydraulic conductivity of fractured rock located in thevadose zone: M.S. thesis, 135 p. (HWR)
Usunoff, E.J., Factors affecting themovement and distribution of fluoridein aquifers: Ph.D. dissertation, 365 p.(HWR)
Vidris, M.R., U.S. smelter acid sales andrevenues: The implications of adoptingEuropean acid trade and marketingpractices: M.S. thesis, 174 p. (MGE)
Vogt, G.T., Porosity, pore-size distribution, and pore surface area of theApache Leap Tuff near Superior, Arizona, using mercury porosimetry: M.S.thesis, 130 p. (HWR)
Vol. 19, No. 2
State of Arizona:
Summer 1989
Governor Rose Mofford
Arizona Geological Survey845 N. Park Ave., #100Tucson, AZ 85719TEL: (602) 882-4795