Proterozoic Geology and Ore Deposits of North-Central Arizona
Proterozoic Geology and Ore Deposits of North-Central Arizona
Edited by Ed De Witt U.S. Geological Survey
Arizona Geological Society Field Trip Spring 1991
Arizona Geological Society p. o. Box 40952 Tucson, Arizona 85717
Proterozoic Geology and Ore Deposits of North-Central Arizona
Edited by Ed DeWitt U.S. Geological Survey
Arizona Geological Society Field Trip Spring 1991
Arizona Geological Society p. O. Box 40952 Tucson, Arizona 85717
Table of Contents
Introduction 2 Day 1 2 RoadLog and Field Trip Guide 2 Papers 14 Excerpts from "Base- and precious-metal concentrations of Early Proterozoic massive sulfide deposits in Arizona--crustal and thermochemicalcontrols of ore deposition," by Ed DeWitt 14
Excerpts from "Geology of Early Proterozoic gold mineralization. alteration assemblages, and geochemistry of theHuron-Victor-Swindler-Montezuma prospects, Yavapai County, Arizona," by P. F. O'Hara and R. C. Long 21
Excerpts from"Geology and alteration assemblages at the BluebellMine, an EarlyProterozoic massive sulfide deposit, Yavapai County, Arizona," by Ed DeWitt 25
Excerpts from "Early recumbent folding during Proterozoic orogeny in central Arizona," by K. E. Karlstrom. Reprinted with permission from Grambling, J.A., and Tewskbury, B.J., eds, 1989, Proterozoic geologyof the southern RockyMountains: Geological Society of America Special Paper 235, p. 155, 160, 162, and 163 28
Day 2 32 Road Log and Field Trip Guide 32 Papers 32 Excerpts from "Geology of the Golden Belt Mine area, Black Canyon metallic mineral district, Arizona," by D. E. Wahl, Jr., and P. F. O'Hara 43
Excerpts from "Tectonic and magmatic contrasts across a two-provinceProterozoic boundary in central Arizona," by C. M. Conway, K. E. Karlstrom, L. T. Silver, and C. T. Wrucke. Reprinted with permission from Davis, G.H., and VandenDolder, E.M., eds., Geologic diversity of Arizona and its margins; excursions to choice areas: Arizona Bureau of Geology and Mineral Technology Special Paper 5, p. 158, II 159, 160, 169, and 170 48 Excerpts from "Geology and structural relations in the southernNew River Mountains and the significance of the Moore Gulch shear zone," by Ed DeWitt S3
Excerpts from "Gravity and magnetic evidence for an EarlyProterozoic crustal boundary along the southern Shylock fault zone, central Arizona," by R. S. Leighty, D. M. Best, and K. E. Karlstrom SS
References Cited S9
Figures Figure 1. Geologic map of the Prescott area 4 Figure 2. Geologic map of the , 'ayer area 10 Figure 3. Geologic map of the New River Mountains area 38
Cover Illustration: Longitudinal section of Bluebell Mine, from Lindgren, Waldemar, 1926, Ore deposits of the Jerome and Bradshaw Mountains qUlJdrangles, A.rizona: U.S. Geological Survey Bulletin 782, Plate 16 INTRODUCTION
The fonnat and content of this pUblication are slightly different from past Arizona Geological Society (AGS) field trip guides and road logs. A road log and field trip guide, with supporting 1:100,OOO-scale geologic maps. are presented for both days of the trip. The maps are both color (with topographic base) and black-and-white (with topographic base) to aid the field trip participant in understanding the stratigraphyno and structure of the area The road log for the trip is . slightly longer than those in most previous AGS guidebooks and contains more geologic information; it was taken, in part, from the road log in DeWitt (1987). Because most of the papers referred to in this guidebook will appear, in entirety, in Arizona Geological Society Digest 19, only parts of the papers are reproduced here. Specifically, the abstract, relevant maps, figures, tables, and conclusions of those papers have been excerpted for this guidebook.
Field trip leaders include: Ed DeWitt, U.S. Geological Survey, Denver, CO 80225 Patrick F. O'Hara, Kaaterskill Exploration, Prescott, AZ 86303 Karl E. Karlstrom, Northern Arizona University, Flagstaff, AZ 86011 David E. Wahl, Jr., Consulting Geologist, Scousdale, AZ 85271 Brooke Clements, University of Arizona, Tucson, AZ 85721
DAYl
The first day of the field trip will concentrate on Early Proterozoic massive sulfide deposits in the Mayer-Humboldt area and Early Proterozoic polyphase defonnation in the Brady Butte area After an initial stop at the Iron King Mine, southeast of Prescott, where we will discuss regional stratigraphic relations. and metal ratios in massive sulfide deposits, our morning stop will be at the Huron-Vietor-Swindler massive sulfide prospects south of Humboldt. These prospects afford a look Early Proterozoic stratigraphic relations and alteration assemblages at low greenschist facies metamorphic grades. After a lunch stop in Mayer, participants can go to either the Bluebell Mine south of Mayer to look at Early Proterozoic stratigraphic relations, alteration, and massive sulfide mineralization, or to the Texas Gulch Fonnation near Brady Butte to review stratigraphy, structure, and polyphase folding.
Road Log and Field Trip Guide
by Ed DeWitt
Day 1 - Morning: Prescott, Arizona, to Iron King Mine and Huron-Vietor-Swindler massive sulfide prospects near Humboldt, Arizona
Road Log from Prescott, Arizona, Iron King Mine: Canyon Granodiorite (fig. 1) exposed in the to 17.8 miles beveled roadcuts.
Cumulative 0.8 Chaparral-covered hillside to theright underlain by mileage Government Canyon Granodiorite and Early 0.0 Prescottonian Motel, Prescott. Tum right onto Proterozoic gabbro. Large hill to the right is Gurley Street and Arizona State Highway 69 to Badger Mountain, composed entirely of this Phoenix. gabbro.
0.2 Intersection with U.S. Highway 89 north to Ash 1.6 Roadcuts on left are in Early Proterozoic metabasalt Fork. Stay to the right, on Arizona Highway 69. and meta-andesite that Krieger (1965) assigned Highway crosses the wash of Government to the Green Gulch Volcanics. Canyon. Roadcuts on the left beneath the Sheraton Hotel are Tertiary fanglomerate that 2.4 Roadcuts through mesa expose basalt flow and locally overlies the 1740,:t15 Ma Government underlying scoria and tuff. Through the roadcut
2 is a vista of the Bradshaw Mountains in the 8.5 Intersection of RobertRoad in PrescottValley. distance to the right. Mount Union. elev. 7,979, View straight ahead toward low hills at the is the highest peak in the Bradshaw Mountains. southern end of the Black Hills is of metasedimentary and metavolcanic strata of the Small dumps on the right side of the Grapevine Gulch Formation. one of the younger road are the Bullwhacker prospect, one of Early Proterozoic sequences in thePrescott several small vein depositsin the Prescott Jerome area (Anderson and Creasey, 1958). metallic mineral district, an Early Proterozoic The Grapevine Gulch is intruded by the tonalite copper-gold quartz vein district(Keith, Gest, of Cherty (DeWitt, 1989) to the south. and others, 1983; Welty and others, 1985). 9.8 Drainageon the right is Lynx Creek, which was 2.9 Turnoff on the right to Walker and Lynx Lake. extensively dredged and placered for gold in the Continue east on ArizonaHighway 69. early 1940's (Wilson. 1961). More than 29,000 Roadcuts on left at this intersection are in fme ounces of gold are known to have been grained granite and alaskite. recovered from the drainage, and a total of 80,000 ounces of gold are estimated to have 3.2 Metavolcanic rocks and metatuff intruded by been recovered (Elsing and Heineman. 1936; Prescott Granodiorite in roadcuts. View ahead Johnson. 1972), making Lynx Creek the second on the horizon. to the north of Woodchute largest placer gold district in the Bradshaw Mountain in the Black Hills, is of the Mountains. Only the Weaver district near Francisco Mountains, elev. 12,670 ft, Sannorth of Congress producedmore gold. From 1902 Flagstaff, Arizona. through 1968 thedrainage of Lynx Creek has produced the most gold of any placer district in 5.2 Glassford Hill, elev. 6,178, on the left is a Miocene? Arizona. Some of the dredge heaps can be seen cinder cone that has been buried by its own in isolated exposures to the right of the basalt flows (Krieger, 1965). highway.
6.0 Mingus Mountain, elev. 7,815 ft, and the Black Hills 11.8 Bridge over Lynx Creek. are in front of us on the skyline from 11:00 to 1:30. The mesa is underlain by basalt flows of 13.5 Turnoff on theright is the Bradshaw Mountains the Miocene and Pliocene Hickey Formation. road. Theunnamed, high peak on the right at Beneath the dark basalt cap is a thin sequence 2:30 is underlain by Early Proterozoic alaskite of Mississippian to Cambrian shelf sedimentary (Crooks Canyon Granodiorite) that forms the rocks that unconformably overlies Early reddish brown cliffs that are obvious from here. Proterozoic metavolcanic rocks that host the massive sulfide deposit at the United Verde 14.2 Silicified metarhyolite at the north end of the Bell mine near Jerome. Peaks to the right, about 4 Ranch prospect (Swan. 1987; Swan and others, miles to the south, are alaskite and aplite that 1981) is visible at 12:15 as the rounded, nearly are probably related to the Crooks Canyon white peak on the near skyline. The town of Granodiorite. Now driving through Prescott Dewey is on the left. VaHey (fig. 1). 14.7 Junction with Arizona State Highway 169 to the To the left at about 9:00 and 15 miles leftthat crosses thetonalite of Cherty to the away, are the northern and westernmost west and connects withInterstate 17 south of outcrops of Mazatzal Quartzite in the hills near Jerome, Arizona. We continue south on DelRio (Krieger, 1965). The Mazatzal Arizona State Highway 69. Quartzite (Wilson. 1922, 1939; Conway, 1976; Anderson and Wirth, 1981) is one of the 16.6 Humboldt, Arizona. Exxon station and old smelter youngest Early Proterozoic stratigraphic units in stack on the left. Turnoff to theleft in about central Arizona. one-quarter mile leads to thebusiness district of the old town of Humboldt.
3 Figure 1 (below and two following pages) . Geologic map of the Prescott area. Data from Krieger (1967), Anderson and Blacet (1972a, 1972b) , Anderson and Creasey (1967) , DeWitt (1987; unpub. mapping, 1989), Anderson (1989), O'Hara (1987, this volume), Swan and others (1981), and Swan (1987).
EXPLANATION D� Quaternary units, undivided Contact . � Tertiary volcanic and sedimentary rocks Fault I TKg I Tertiary to Cretaceous granite to granodiorite •. Route of field trip Iw!li,li!:ilil!ll� Texas Gulch Formation 0 Stop number � Prescott Granodiorite I Xgc I Government Canyon Granodiorite Crooks Canyon Granodiorite � o 1 2 3 mi Pelitic metasedimentary rocks 3 km o 2 � --=====-- I Xgb I Gabbro Scale: 1 :100,000 Metachert and iron-formation � Base from U.S. Geological Survey Metarhyolite Prescott, 1981 and . � Bradshaw Mountains, 1981 � Metatuff � Metabasalt and meta-andesite
4 � �
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To Ash Creek
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16.9 Tailings ponds of the Iron King Mine clearly mineral district (Keith, Gest, and others, 1983). visible on the right and slightly above us. Large Other, much smaller deposits such as those at roadcut in Tertiary fanglomerate directly ahead. the Hackberry, Boggs, and Long Pine mines, Theturnoff to the Iron King Mine ison the also averaged about 0.1 oz/ton Au. more than right, past this roadcut. 3.0 oz/ton Ag, and as much as 2.3% Pb (DeWitt. this volwne). Deposits in the Big Bug 17.2 Turnoff on the right to the Iron King Mine. Take districthad among thehighest gold grades and the flrst of three turnoffs to the right and stay on lowest AgJAu rations(-25) of any Early the main road. Tailings ponds of the Iron King Proterozoic syngenetic deposits in Arizona Mine are visible on the right. (DeWitt, 1983).
17.8 Pavement ends. Waste dwnps on the left; tailings After the stop at theIron King mine we ponds on the right. The old Iron King assay will return toHwnboldtand drive to the Huron office is on the right. Thiswill be our flrst stop Victor-Swindler prospects. of the day.
STOP 1. Iron King Mine. Assemble at the western Road Logfrom Humboldt Huron-Victor-Swindler to dump piles near the discovery outcrops for a prospects: 2.7 miles discussion of the regional geologic setting of Early Proterozoic massive sulflde and the Cumulative. distribution of precious metals within those mileage deposits. 0.0 Humboldt, Arizona. Proceed south on Arizona Highway 69 toward Mayer (flg. 1). Thelarge and famous massive sulflde deposit at Jerome is characteristic of only one 0.1 Deep roadcut in fanglomerate. Dump on the leftis typeof volcanogenic massive sulflde deposits in at the Lone Pinemass ive sulflde deposit Arizona. That depositis developedat the top of (Anderson and Blacet, 1972b; Webb, 1979). On a thick succession of rhyolite, has a very large theskyline in the distance at 12:00 and 1:00 are chlorite pipe beneaththe massive ore, and the Big Bug Mesa and Little Mesa, capped by ore grades laterally into chert. tuff, and basalt of the Hickey Formation. volcanogenic sediments (Anderson and Nash. 1972; DeWitt and Waegli, 1986; Lindberg, 1.1 Dumps on the right at 9:00, along the base of Spud 1986; Vance and Condie, 1987). Other Mountain, are on theSilver Belt-McCabe and deposits, such as the Iron King, Bluebell, and Kit Carson vein systems. Mines visible from DeSoto, lack the extensive chlorite pipes. Some here include the Silver Belt, Arizona National, deposits, such as the Binghampton Copper and Lookout, all in theTiconderoga district, a Queen, are developed within rhyolite flows and Late Cretaceous to early Tertiary lead- and tuffs. The signiflcance of these differences will silver-rich vein system (Lindgren, 1926; be one of the many topics of discussion at this Anderson and Creasey, 1958) a.ssQCiated with stop and at the moming stop at the Huron theLaramide stock at Poland Junction to the Victor-Swindler prospects. south(Anderson and Blacet, 1972b; Sturdevant, 1975). About 15 mines in thedistrict accounted The Iron King mine, the third largest massive sulflde for most of the 340,000 tons of high-grade silver deposit in Arizona, produced about 6,200,000 ore; some mines averaged more than 20 oz/ton tons of ore from 1903 through 1969 that Ag. TheTiconderoga district was the largest averaged 0.11 % Cu, 1.88% Ph, 4.95% Zn, 0.073 producer of all theLate Cretaceous to early oz/ton Au. and 2.69 oz/tonAg (Arizona Tertiary vein districts in theBradshaw Geological Survey, unpub. data, cited in Mountains. Other large producers include the DeWitt. this volwne). The deposit had the Walker and MountUnion districtsto the west of highest precious metal concentrations of any Ticonderoga, and theTiger district near Crown massive sulflde deposit in Arizona (DeWitt. King. Although it is not visible from the 1983) and was unusual because of its very low highway, the McCabe-Gladstone mine produced concentration of copper and high concentration about 70% of the ore from thedistrict. An of lead. attempt was made in thelate 1980's to put the mine into production, but the attempt failed. The Iron King mine is the largest massive sulflde deposit in the Big Bug metallic
7 1.6 The prospect pits at the farsouth end of the high 0.0 Huron-Victor-Swindler prospects south of Iron King voltage transmission line are the Victor Mine. Turn south on Arizona Highway 69 Swindler prospects, which will be visited as part toward Mayer. of the next stop. 0.8 Mount Elliott, elev. 6,980 ft, on the skyline at the 2.4 Approaching the high voltage transmission lines. righL Bold cliffs of Mount Elliott are composed Just past the No Passing sign on the left of the of Crooks Canyon Granodiorite, an Early highway is the turnoff to the Huron and Proterozoic pre-tectonic leucocratic pluton Montezwna prospects. Turnoff the highway to (Anderson and Blacet, 19718; DeWitt, 1989) the left, onto dirt road. Ifyou drive underneath that forms extensive outcropsin the the transmission lines, you have gone too far. southwesternpart of thePrescott area In the foreground are bouldery weathering outcrops. of 2.7 Take trail up to intersection with pipeline road. the Laramide stock at Poland Junction (ftg. 1). Park here for the ftrst of several stops at the massive sulfide prospects. 0.9 Roadcut exposesmeta-andesite and metabasalt flows of the Iron King Volcanics. STOP 2. Massive sulftde prospects. Old workings at this stop include the Victor-Swindler prospect at 1.1 Poland Junction. Road to Walker leads to the right the south end of the mineralized zone and the and follows the route of a 1900's narrow gauge Huron-Montezwna prospect at the north end railroad bed. The Poland-Walker Tunnel cut (O'Hara, this volume). Less than 1,000 tons of through the of Eugene Ridge and ore were produced from the prospects that we connected thecrest Walker district withthe smelter will visit, but the deposits are extremely at Humboldt (Lindgren, 1926). The drainage instructive for their patterns of alteration. divide along the highway is capped by Quaternaryto Tertiarygravel that locally During the early 1980's this area was conceals the metavolcanic strata. Ridges of investigated extensively by a variety of ferruginous metachert and iron-formation American and Canadian companies. Their protrude above thegravel, especially near the fmdings, including the documentation of Boggs (Hurlbut, 1986) and Iron Queen mines to aluminosilicate alteration, and quartz the left at about 10:00. Behind and to the right magnetite-epidote alteration below one of the at 5:00 are the dumpsof the Henrietta Mine. chert and rhyolite horizons, will be discussed at this series of stops. The ftrst stop will View straight ahead in the far distance concentrate on relations in the southern is of the New River Mountains. Thejagged outcrops, where the quartz- magnetite-epidote peaks are composed of -1700 Ma metarhyolite assemblages affecting andesite protoliths is well similar to the Red Rock Rhyolite and other ash displayed. After we ftnish at this stop, we will flowtuff units in the Tonto Basin area (Wilson, go to the north, near the Huron-Montezwna 1939; Gastil, 1958; Conway, 1976; Karlstrom shaft and Conway, 1986).
At the Huron-Montezwna prospect the 1.4 Big Bug Mesa on the right at 3:00is capped by effects of aluminosilicate alteration on rhyolite basalt flows of the Miocene and Pliocene and quartz porphyry bodies will be emphasized, Hickey Formation, which consists of as will the complex structural setting of the fanglomerate, siltstone, lakebed sediments, and volcanic rocks, which is well displayed in prominent mesa-capping basalt flows, and polished outcrops along the creek bottom. If ranges in age from about 15 Ma to 11 Ma time permits, we will then go up the hillside to (McKee and Anderson, 1972; McKee and the west to view some spectacular outcrops of Elston, 1980; arized in Reynolds and andalusite-quartz-sillimanite rock. others, 1985). summ
1.9 Dredge tailings are visible on the right in the Road Log fr om Huron-Victor-Swindler prospects to drainage of Big Bug Creek. The creek was Mayer: 5.5 miles placered extensively in the early 1940's (Wilson, 1961). Recordedproduction is more Cumulative than 17,000 ounces of gold; estimated total mileage production is 50,000 ounces of gold (Johnson, 1972), making the drainage of Big Bug Creek
8 the third largest placer district in Arizona. Mine, a small massive sulfide deposit that From 1902through 1968, Big Bug Creek was produced only a few hundred tons of ore. the second largest producer of placer gold in However, that ore averaged 7.6% Zn and 0.3 Arizona. Only the drainage of Lynx Creek oz/ton Au (DeWitt, this volume). produced more gold. Small-scale placer operations are currently active along the lower 4. 1 Turnoffto the right leads to the main street of reaches of the creek, both above and below Mayer. We stay on Highway 69. Mayer. 4.8 Swckpile of travertine on the rightside of the On the right at about 1:30 or 2:00,past highway. Roadcut is in travertine, which is the placer workings, are dumps of the quarried onboth sides of the highway. Hackberry and Pentland mines. The mines are the southernmost massive sulfide deposits in the 5.3 Bridge Big Bug Creek. Town of Mayer on Big Bug district. The Hackberry produced theacross right. HillsMotel and Restaurant on the slightly more than 20,000 tons of ore that. right. during its peak years of production, averaged 1.6% Cu, 2.3% Pb, 5. 1 % Zn, 3.6 oz/ton Ag, and 5.5 Intersection of Central Avenue in Mayer. Tum 0.12 oz/wn Au. Behind and to the right at about right. toward the Circle K store. We will 4:30 are the dumps of the Butternut mine, a assemble near the city park for lunch. Straight small, gold-rich massive sulfide deposit that aheadis a smelter stack, which was completed averaged about 0. 17 oz/ton Au (DeWitt, this just before one of the downturns in the silver volume). market during the early 1900's, and was never used. 2.8 Dumps on the right at 3:00are from the Upshot
Day 1 - Afternoon: Mayer, Arizona to Bluebell Mine
or
Mayer to Texas Gulch Formation at Brady Butte
Road Log fr om Mayer Texas Gulcb Formation at 1.8 Crest of small hill. Mayer Cemetery on right. to WolfCreek: 7.5 miles. Brady Butte at 12:00 on skyline isunderlain by 1750 Ma pre-tecwnic Brady Butte Granodiorite. Cumulative Towers Mountain at 11:00 on skyline is Mileage underlain by Early Proterozoic gabbro-diorite 0.0 Circle K Store in downtown Mayer. Tum right on body. Subdued topography that road crosses is Central; road swings gently to the right metabasalt and meta-andesite
0.3 Tum left on Miami, just past 2-story hotel on left 3.6 Road bends to left. Crossing contact. from dark weathering metabasalt to light weathering Texas 0.4 Stop sign. Tum right on Main Gulch Fonnation.
0.5 Tum left on Fairlan Street. just past Double D baron left. Go straight ahead on Wicks Avenue past Mayer Christian Fellowship Church on left.
0.6 Stop sign; tum lefton Jefferson
1.0 Crest of hill. Early Proterozoic metabasalt outcrops begin (fig. 2).
1.5 Fork in road; stay w right on main road.
9 Figure 2 (below and two following pages). Geologic map of the Mayer area. Data from Anderson and Blacet (1972a, 1972b), DeWitt (1976, 1979, 1987, unpub. mapping, 1989) , Blacet (1985) , Anderson (1989), Jerome (1956), and Karlstrom (1989).
EXPLANATION
Quaternary units, undivided Contact � Tertiary volcanic and sedimentary rocks; dikes Fault I TKg I Tertiary to Cretaceous granite to granodiorite --"".� Route of field trip r4\ l:mm::m::i::l � Texas Gulch Formation '\..J Stop number � Crazy Basin Quartz Monzonite Ilillllllllll!11111 [ xbml Bumblebee Granodiorite � Badger Spring Granodiorite Xbb Brady Butte Granodiorite I I o 2 3mi Pelitic metasedimentary rocks � o 2 3km Xgb Gabbro I I Scale: 1:100,000 � Metachertand iron-formation Metarhyolite II � Base from U.S. Geological Survey � Metadacite Bradshaw Mountains, 1981 � Metatuff Metabasalt and meta-andesite 1IIIIIImii �
10
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4.5 BulIroad trail #202 to left; stay on main road. In onto paved road. Cross cattle guard and take Texas Gulch Fonnation; regional foliation dips immediate left onto gravel road. east. 1.3 Crossing beneath high tension power lines. Waste 5.5 Top of ridge. Trail leads to left. Continue straight piles of the Bluebell mine are to theright of the and descend into Mule Canyon. road, below the circular house on thehillside. Ore from the mine was trammed overland a 5.7 Mule Canyon. In Texas Gulch Fonnation; regional distance of three miles to an old railroad siding foliation dips steeply west from thispoint to at the foot of the waste piles. Remains of the WolfCreek. towers for the tramway are visible in places.
6.1 Cattle guard. Beds in Texas Gulch Fonnation dip 1.9 Road (j93)to BluebellMine to the right at top of gently; foliation dips steeply west. small ridge. Driving in Tertiary Hickey Formation. 7.0 Ridge top. Descending into WolfCreek. Brady Butte on left 2.1 Cross cattle guard at of ridge crest 7.4 Trail #304 to right. Stay on main road. 2.2 Y in road; take left fork. Bluebell Mine visible in saddle at 10:00. Brady Butte at 12:00. Big Bug 7.5 Crossing Wolf Creek. Turn left on trailjust past the Mesa at 1 :00. Creek. Park here. 3.8 Top of small ridge. Y in road; take left fork STOP 3A, Texas Gulch Fonnation stratigraphy and structure to be discussed here. Features to be 3.9 Trail leads to left; stay on main road noted are the unconfonnable contact of the Texas Gulch Fonnation and the underlying 4.4 Cross CedarCreek. Outcrops of EarlyProterozoic Brady Butte Granodiorite (Blacet, 1966), the metabasalt, metarhyolite, and iron-fonnation nature of the contact of theTexas Gulch visible on both sides of road. Fonnation and older metavolcanic strata (O'Hara and others, 1978), and the polyphase 5.2 Saddle above Bluebell Mine. folding of the Texas Gulch Fonnation (Karlstrom and O'Hara, 1984; Karlstrom , 5.4 Cuts on right are part of Bluebell Mine. Sericitized 1989). and hematite-stained metarhyolite now quarried for decorative facing stone. Return to Mayer when finished, and
then to Prescott for the evening. 5.7 Y in road. Take right fork to foundations of Bluebell shaft. Park vehicles here. Road Log fr om Mayer Bluebell Mine: 5,7 miles to STOP 3B. Bluebell Mine. The Bluebell Mine was the Cumulative largest producer of massive sulfide ore in the Mileage Mayer metallic mineral district, which also 0.0 Intersection of Arizona Highway 69. Turn right contains the DeSoto mine southwest of Mayer. toward Phoenix. The Bluebell produced about 1,100,000 tons of ore that averaged 3.13% Cu, 0.048 oz/ton Au, 0.1 Roadcut east of smelter stack begins in Tertiary and 1.23 oz/ton Ag (DeWitt, this volume). fanglomerate, but quickly passes into highly Features to be discussed at this stop include foliated tuffaceous metasedimentary strata, stratigraphy of the mine area, structural quartz veins, iron-fonnation, tuffaceous rocks, features, especially isoclinal folds affecting all and meta-andesite (fig. 2). metavolcanic units, and alteration assemblages in footwall units of the ore deposiL 0.9 Black Canyon Mobile Home Sales area on right, ahead. Turn hard to the right before sales area Return to Mayer when finished, and then to Prescott for the evening
13 Excerpts from "Base- and precious-metal concentrations of Early Proterozoic massive sulfide deposits in Arizona-crustal and thermochemical controls of ore deposition," by Ed DeWitt.
Base- and precious-metal concentrations of Early Proterozoic massive sulfide deposits in Arizona--crustal and thermochemical controls of ore deposition.
Ed DeWitt M.S. 905, U.S. GeologicalSurvey, Denver, Colorado 80225
ABSTRACI' of ore deposition, not regional factors, wereimportant in Of the 70 known EarlyProterozoic massive sulfide the localization of these high-gradeprecious-metal deposits and prospects in Arizona, have productiondata deposits. Deposition of oreminerols at temperatures below 48 that are here summarized and that can be used toinfer 3000 C from a sulfur-rich brine is the most likely causeof differencesamong the originsof the various deposits. the enhanced precious-metal concentrations,not formation Thirteen massive sulfidemetallic mineral districts contain of the deposits in a setting distalfrom volcanism. mines and prospects that,from 1884 through1978, Low-Au, low-Ag ore, locallypresent in the Agua 48 produced55.3 million tons of ore that contained 3.99 and Verde districts, also contrasts markedlywith theFria billion pounds of Cu, 237 million pounds of Pb, 1.0 billion average for districts in the Prescott·Jerome area. A likely pounds of zinc, 75.2 million ounces of Ag. and 2.0 million causeof this depletion in precious metals is deposition of ounces of Au. Average oregrades were 3.6% Cu, 0.2%Pb, oreminerals in these deposits fromhydrothermal 0.9%Zn, 1.36 o7/tonAg, and 0.037 o7/ton Au. Because Pb fluids having temperatures in excess of 3000 C, a temperature and Zn were produced sporadically, grades of any deposit high for most chloride- and sulfide-complexes to transporttoo . that contained Pb and Zn are higher than the averages largeconcentrotions of gold and silver in solution. above, about 0.5% Pb and 3-100/0 Zn. AgJAu values of all Deposits of this type appear to have formed within rhyolite deposits averoged 37, but ronged from 8 to 462for deposits flows and tufTs, not at the contactof felsic and moremafic producing more than 20,000 tons of ore. Precious metal concentrotions ronged from less than 0.001 to 0.12 o7/ton rocks. for Au and from 0.009 to 3.56 o7/ton for Ag in deposits that INTRODUCTION produced more than 20,000 tons of ore. Early Proterozoic massive sulfide deposits associated Low-Au, low-Ag, high AgJAu ore of the Hualapaiand with submarinemafic to felsic metavolcanic rocks are Old Dick districts contrasts markedly with the average for presentthroughout central, west-central, and northwestern districts in the Prescott·Jerome area and these differences Arizona (Anderson and Guilbert, 1979; De Witt. 1983, were likely caused by regional differences in the crust 1987; Keith and others, 1983, 1984; Eastoe and others, underlying western Arizona. Mojave.type crust, 1987; Donnelly andConway, 1988; Lindberg,1989). 207 204 charocterized by elevated pb/ pb and Th/Uvalues Production data for copper,lead,zinc, gold, and silver compared to centrol Arizona,underlies western Arizona (Arizona Geological Survey,unpub. data) for most of the and was partially melted to form much of the metavolcanic known deposits and prospects in thirteen metallic mineral strota that host massive sulfide deposits in the Hualapai districts (Welty and others, 1985) are here summarized. and Old Dick districts. Apparently, Early Proterozoic Nine of the thirteen districts have recorded production; Mojave·type crust is impoverished in precious metals only the Gray's Gulch and BroncoCreek districts north of compared to the crust underlying central Arizona. Phoenix and the Pittsburg-Tonto and Pranty'sCabin Younger (post-1730 Ma and Phanerozoic) vein districts south of Payson (fig. 1) lack data and are not deposits in centro and westernArizona that formed discussed. These four districts produced a minimal amount largely in plutonicI that intruded Mojave-type crust of ore; omission of their totals does not materially affect are charocteristicallyrocks Au-rich and have low AgJAuvalues. the trends noted for the region as a whole. Production data This metallogenic signature is believed to be a crustal-scale for the remaining nine districts, which contain 48 mines for phenomenon related to emplacement of voluminous which metal data are available, allow trends in metal plutons from 1690 to 1740 Ma that largelyobliteroted the contents and ratios from mine to mine and district to metallogeniccharacterist ics of the EarlyProterozoic district to be noted. Many of thesefeatures were noted by Mojave-typecrust. DeWitt (1983) and Lindberg (1989),but others were not. Low-Cu, high-Pb ore of the Big Bug district contained Data used in this paper have been thoroughly checked the highest precious metal concentrations, Au averaging for accuracy and completeness; however omissionsare 0.075 o7/ton and Ag averoging 2.65 o7/ton. Small deposits probably the most likely source of error. Small mines and having metal rotios similar to the averoge for the Big Bug deposits are particularly likely to have incomplete records district are noted in the Old Dick,Verde, and Agua Fria of their production, as are many mines that operated in the districts, and indicate that local thermo-chemical controls late 1800's and earliest 1900's. Because of these drawbacks,
14 Excerpts from "Base- and precious-metal concentrations of Early Proterozoic massive sulfide deposits in Arizona-crustal and thermochemical controls of ore deposition," by Ed DeWitt.
relationships of metal contentsand ratios and trends are within the deposits, and instead possess extensive areas most reliable for large mines and thosewith complete and having sericite- and minor chlorite-rich rocks. Some, such verifiable records. Some published production data for as the Huron, Swindler, and Orizaba, have alteration pipes massivesulfide deposits in Arizonaare in disagreement characterized by aluminosilicate-rich rocks and epidote with the data summarized here (examples are the Iron King (O'Hara, 1987, this volume; DeWitt, unpub. data, 1989). mine in the Big Bug district- Gilmour and Still, 1968 and Some deposits have been studied in detail.principally some of the notes in Donnelly and Conway, 1988); data the Iron King mine in the Big Bug district (Gilmour and summarizedin this paper should supersedeearlier Still, 1968 and referencescited therein), the Bruce minein summaries. Rigorous statistical treatment of the the Old Dick district (Baker and Clayton, 1968; Larson, production data is not deemed appropriate,as ore types 1984 and references cited therein) the United Verde mine have been somewhat homogenized by the reporting of in the Verde district (Anderson and Creasey,1958; amounts of ore and metals on a yearly basis. Lindberg, 1989; DeWitt and Waegli, 1989; Gustin, 1990), and the United Verde Extension mine in the Verde district DISTRIBlITION, AGE, CHARACfERISTICSOF (White, 1986a). Others, principally the Copper Queen DEPOSITS AND mine in the Agua Fria district (Brook, 1974), the Antler Metavolcanic rocks of basaltic to rhyolitic compositionare and CopperWorld mines in the Hualapai district (Romslo, host to numerous Early ProterozoiC, syngenetic, massive 1948; More, 1980), and the Copper Chief mine in the sulfide deposits in central Arizona. Although most of the Verde district (Johnson, 1986b; Lindberg, 1986b), have depositsare in the Prescott·Jeromeregion of central been investigated in less detail. Many, however, have not Arizona, mines and prospects are noted from the northwest been mapped or sampled since Lindgren's (1926) report on part of the state (Hualapai district in the northern mines in the Prescott-Jerome region. This paper and Hualapai Mountains) to the east-central part of the state previous summaries (Anderson and Guilbert, 1979; (pranty's Cabin district in the Sierra Ancha southeastof DeWitt, 1983; Lindberg, 1989) reveal trends in metal Payson). Thedeposits are contained within 1700-1780 Ma concentrations that are caused by first-order crustal metavolcanic strata. Alldeposits in the Prescott-Jerome differences and second-orderthermo-chemical conditions area (fig. 1) are hosted by 1740-1780 Ma maficto felsic of ore deposition. Obviously, additional work on most metavolcanic strata (Anderson and others, 1971; Anderson deposits is necessary before all are fully understood. and Silver, 1976; Anderson, 1978, 1987, 1989a, 1989b; Donnelly and Hahn, 1981; Bowring and others, 1986; OVERALLDISTRICf SlTh'IMARY Karlstrom and others, 1987). Deposits in the western part The 48 massive sulfide deposits in Arizona for which
of the state (Hualapai and Old Dick districts) are production data ar _ available produced 55.3 million tons of contained in mixed metavolcanic and metasedimentary ore that contained 3.99 billion pounds of copper, 237 strata that are about 1730 Ma (Silver, 1968; Bryant and million poundsof lead, 1.02 billionpounds of zinc, 75.2 Wooden, 1986; Chamberlain and Bowring, 1990; Wooden, million ouncesof silver, and 2.06 million ounces of gold unpub. data, 1990). Those deposits near Paysonare (table 1). From all districts, ore averaged 3.6% Cu, 0.2% associated with felsic to mafic metavolcanic strata that are Pb, 0.9% Zn, 1.35 oz/ton Ag, and 0.037 oz/ton Au. 1700-1730 Ma (Gasti� 1958; Ludwig, 1973; Conway, 1976; Averaged lead and zinc grades are artificially low, as most Silver and others, 1986; Conway and Karlstrom, 1986; mines did not produce lead- and zinc-rich ore becausethey Karlstrom and others, 1990). Massive sulfidedeposits are were penalized at the smelter for zinc. Lead, when not associated with Early Proterozoic, predominantly produced,normally averaged less than 0.5% except for subaerial. felsic metavolcanic rocks (Wilson, 1939; Conway, deposits in the Big Bug district. Zinc, when produced, 1976; Conway and Silver, 1989) that are younger than 1700 averaged 3-10%. Copper, silver, and gold grades accurately Ma nor with the pelitic and psammitic Pinal Schist of reflect the metal concentrations of the deposits because southeasternArizona. these metals were always profitably extracted. Therefore, Some deposits, such as the United Verde, Bruce and the combined Cu-Pb-Zn content of most depositsaveraged Old Dick. and to a lesser extent the Stoddard and about 7%, but was lead-poor. Silver/gold ratios averaged Antler,have the classic features associated with submarine, 37 but varied from 183 for the Old Dick district to 12 for volcanogenic deposits (Hutchinson, 1973; Franklin and the Zoniadistrict. others, 1981): stratabound nature, massive sulfide ore at Of the nine massivesulfide districts for which the top of a major rhyolite body, zonal arrangement of production data are available, the Verde districtproduced metals within the deposit, and chloritic alteration pipe by far the most ore and metals (table 1). Sixty-nine percent beneath the deposit. Others, such as the Iron King, of the ore, 93% of the copper, 74% of the silver, and 73% Bluebell, Copper World, and Kay, appear to lack of the gold were produced from this district. The United recognizable chlorite alteration pipes and metal zonation Verde mine, the third largest massive sulfide deposit in
15 Excerpts from "Base- and precious-metal concentrationsof Early Proterozoic massive sulfide deposits in Arizona--crustal and thermochemical controls of ore deposition," by Ed DeWitt.
Big Bug District The Big Bug district is northwest of the Agua Fria The Hackberry mine (Lindgren, 1926), the second district (figs. 1 and 5) and is characterized by massive largest producerin the district, is alsorich in lead, silver, sulfide deposits spatially associated with one metarhvolite and gold (table 3). The deposit is localized at the contact tuff that is overlain and underlain by metabasalt (Li�dgren, of metarhyolite and metabasalt is probably at the same 1926; Creasey, 1950, 1952; Gilmour and Still, 1968; stratigraphic position as the Iron King mine to the north. Andersonand Blacet, 1972b; Bouley and Hodder, 1976; Pyrite-chalcopyrite-galena-sphalerite-tetrahedrite is the Webb, 1979; Andersonand Guilbert, 1979; DeWitt, 1983, ore assemblage. Ag/Au fo r most of the lifetime of the mine 1987; Anderson, 1986a, 1989a; O'Hara, 1986; O'Hara and is rather constant (fig. 11). Silver correlatesvery well with Armstrong, 1986). The district has the lowest coppergrade lead, but lesswell with zinc (fig. 11). and indicates that and the highest lead, silver, and gold grades (table 1). precious metals are mostly associated with galena. Lead Although production from the district is highly biasedby and zinc, when produced, averaged 237% and 5.25%, the Iron King mine (table 3), which accounted for 99% of respectively fo r the deposit. the ore, 94% of the copper,and 99% of the precious Smaller mines in the district have the fo llowing notes. metals, all the small deposits (fig.5) have Silver grades of 1- Totals for the Butternut are highly influenced by data for 4 ovton and gold grades of 0.1-0.4 oVton. Likewise,except 1903, which account for half the total ore produced and for the Butternut and Lone Pine, all coppergrades for much of the veryhigh -grade material. Data for the Lone smallmines are less than 2%. Therefore the district as a Pine include high-grade lead and silver ore for 1924, which whole is copper-poor and lead-, silver-, and gold-rich. Zinc, may not be entirely representative of most are from the when produced, was average compared to most districts. deposit. The Boggsmine (Hurlbut, 1986) is one of the Cambrian, Pb-, and Au-rich massive sulfide deposits in highest-grade deposits for precious metals in the area. The Huron and Victor-Swindler prospects (O'Hara, 1987a; this westernTasmania bear a striking resemblance to those in the Big Bug district (Large and others, 1989). volume) are characterize d by enensive alumino-silicate The Cu-poor, Pb-, Ag-, and Au-rich depositat the Iron assemblages and development of quartz-epidote in the King mine (Lindgren, 1926; Mills, 1941, 1944, 1946, 1947; footwall of the massivesulfide deposits. Hendricks, 1947; Creasey,1950, 1952; Kumke and Mills, The BellRanch prospect (Swan and others, 1981; Swan, 1950; Anderson and Creasey, 1958; Mitchell, 1964; 1987; O'Hara, 1987b), located southeast of the Lone Pine Gilmour and Still, 1968; Lawrence andDixon, 1986) is mine, has produced no are, but is similar in most regards to localized along altered metarhyolite units within a other mines in the Big Bug district. Gold- and silver metabasaltic to andesitic flow sequence. Ore minerals are bearing pyrite,chalcopyrite, and arsenopyrite are present sphalerite-galena-pyrite-tennantite-arsenopyrite in and adjacent to metarhyolite. Verylittle massive sulfide ore is known. The BellRanch prospect may be a gold-rich chalcopyrite. Production data fo r the mine reveal end-member of the precious-metal-rich depositsin the Big moderate correlation of copper with gold (fig. 6) and Bug district. copper with silver (fig. 7), but a much better correlation of In summary, fo r the Big Bug district, highest precious lead with gold (fig. 6), especially fo r gold grades less than . metal grades are in deposits having the highest lead 0.1 ovton. Data points that lie to the lower right of the concentrations. The district as a whole is very lead-rich and major positive correlation of gold and lead - those having has the highest silver and gold grades in the state. The high precious metal concentrations and low lead concentrations - come fro m pre-1940 production (fig.8) in Ag/Au of 35, which is the same as the state average, which oxidized(?), anomalously gold- and silver-rich ore indicates that both precious metalsare preferentially enriched in the district, and suggeststhat gold and silver having unusually low base-metal concentrations was mined. are spatially associatedwith galena in the deposits. Elimination of those pointsfro m figs.6 and 7 strengthens the positive co rrelationof precious metals, especially gold (fig. 8) with lead. Variations in Ag/Au are caused more by shifts in gold grade that shifts in silver grade (fig. 9), which remained quite constantfro m 1940 to 1970 (fig 10). Creasey (1952) and Gilmour and Still (1968) suggest that silver is present in tennantite, but metallurgical tests have not proven that association. Both authors state that gold appears to be associated with pyrite, galena, and sphalerite. However, the production data (fig. 6) show that much gold is spatially associated with galena. Neither precious metal correlates well withzinc, but importantly,high zinc grades do not indicate low precious metal concentrations (figs 6, 7, and 8) ..
16 Excerpts from "Base- and precious-metal concentrations of Early Proterozoic massive sulfide depositsin Arizona--crustal and thermochemical controls of ore deposition,"by Ed DeWitt.
Table 1. Massive sulfide district production data, Arizona [Data from Arizona GeologicalSurvey, unpub.data; ell, copper;Pb, lead; Zn,zinc; Ag, silver; Au, gold; 1,short tons; lb, pounds;02, troy ounces;0711, troy ouncesper short ton; no entryindicates no record of production for that element; 0.00indicates that the gradeof the element is less than 0.00999; 0.000 indicatesthat the grade of the element is lessthan 0.000999; Copper, silver, and gold amounts and grades accurately reflectmetal concentrations and ratios in the massive sulfide deposits because these metals normally were produced throughout mining of the deposit;Lead and zinc amounts and grades, in most instances,do not accurately reflect concentrations and ratios in the deposits because lead and zincseldom were producedthroughout the lifetime of the deposit - seethe text fo r ratios that are closerto actual].
DISTItlcr Cu (lb) Pb (lb) Zn(lb) A, (OE) AU (OE) Cu ('JI» Pb('JI» A, Au AI/Au 3.24 0.00 0.00 0.261 o.OOS '3 Agu. Fri. 181.301 11.738.165 3.319 16,480 47.3S3 894 . Zn('JI» (ozII) (oz/l) Ore (1) 0.11 1.84 4.116 2.659 o.07S 35 Bi, BuS 6.321,997 14.379,240 232.532.742 614.%0.375 16,808.5S3 473.885 3.51 0.603 0.004 148 Hualapai 161,990 7,246.119S 896,m 11,3711,100 97,657 659 2.24 0.28 S.79 0.26 1.0'70 0.0:58 18 Kay 2.S55 295,973 � 2.m 149 1.lS9 0.046 25 Mayer 1,401,870 83,67S,564 1.624.804 65,06<1 2.98 . 12.682 197 2.12 0.425 0.007 64 New River 29,873 1,267,428 9.06 0.387 0.002 183 Old Dick 1,683.702 106.79 1,361 3.035, 113 30:5,0:56.606 651,325 3,550 3.17 0.09 1,514.457 4.91 0.00 0.13 1.473 0.040 Verde 37,996.107 3. 733,706.691 693,= 94.994.869 55,9S2.061 37 0.20 0.00 0.001 0.000 Zenia 7,5 19,678 30, 317,238 801 4.019 340 12
026, 98,4 2.0:59, 19S 3.61 0.21 0.93 0.037 37 TOTAL 55,299,073 3,989,418.553 237, 17S,S41 1. 3 30 75,201,189 1.360
Table 3, Massive sulfide depositproduction data, Big Bug district rSee headnote of table 1 for explanation],
DEPOSIT On: Cu (Ib) Pb (Ib (OE) Pb AI Au (oz/l) AI/Au 582 17,920 2.047 233 1.54 3.517 0.400 9 80"" (1) ) Zo(lb) Aa(oz) Au Cu(") ('lII» Zn (") (ozII) Butternut 806 103,373 4.149 136 6,41 '.148 0.169 31 Hec:ltbeny 211.108 644,704 S09,839 1.117,045 71.617 2,306 1.60 t.27 2.78 3.562 o.lU 31 Huron 609 18,300 589 45 1.50 0.967 0.074 13 Iron Klns 6,298,235 13.482.716 232.022,81' 613.843.330 16,726,396 470,892 0.11 1.84 4.87 2.656 0.07' 36 Lone Pine 1.23S 99, 341 88 3.3'8 1116 4.02 0.00 2.719 o.Ul 18 Swindler 271 7.Ul 201 40 1.32 0.742 0.148 5 Upoho1 lSI s,m 196 47 1.90 1.298 0.311 4
TOTAL 6,321.997 14,379,240 232.532.742 614.960,373 16,-.,n 473.88S 0.11 1.84 4.116 2.659 o.07S 35
17 Excerpts from "Base- and precious-metal co ncentrations of Early Proterozoic massive sulfide depositsin Arizona stal and thermochemicalcontrols of ore deposition," by Ed De Witt. -cru
Figure 2. Location map of mines in the Agua Fria district. Basefrom Bradshaw Mountains 1:100,000, 1981. Figure 5. Location map of mines in the Big Bug Mine names in italics are massive sulfide depositsfor which district. Basefrom Bradshaw Mountains and Prescott production data are not available. Mines having 1:100,000, 1981. Mine names in italicsare massive sulfide questionable locations are shown with a query (7). depositsfor which production data are not available.
R.IE. R.IlJ2E. R.2E. R.IE.
i Yallar Kid?
Halfmoon '\ • ' \1,,;:, ,.. .,...... :..--J'
,< �. : . � /
R.IW. R.IE.
18 Excerpts from "Base- and precious-metal concentrations of Early Proterozoic massive sulfide depositsin Arizona--crustal and thermochemical controls of ore deposition," by Ed DeWitt.
Figure 8. Plot of year of production vs. gold, lead, zinc in the Iron King mine, 1936-1969. Symbols on the x-axis Figure 9. Plot of year of production vs. silver/gold, indicate no data fo r zinc. silver, gold-100 in the Iron King mine, 1936-1969.
IronKing Mine IronKing Mine Year Au, and grades Year AgJAu, Ag, and Au grade vs. Pb, Zn vs. 8 80
,.. .. , ,lIE •" � -.i � � 0.4 �'" \ , .. 12 0 I ," .. EJ...... III ,..x>", .. 6 70 .. , '5 lIE .. )0 10 8 ,e o �\ • .. � .,. � " �. c 0.3 'III ;� .?' .. N " '0 '5 \ .. 4 � �4O � < ,£." • « "+. �, \; ! 6 � 50 ... ,. .. .. ,� .D C0 « • , / 30 0.2 .. "" .¥"" ..... \. : �., � ...... � \J.. " ! 1 �, �� ...�. til ...... �r' ....,.,- "' < ,.,./\;, ...... � I � , �!\ � "" :i- 4 \ 0.11 ,+.,;.... �J 12 20 :;.;. Ag • ot:::,?, )J' EJ/ ...... 10 2 1935 1940 1945 1950 Year 1955 1960 1965 19700 1935 1940 1945 1950 Year 1955 1960 1965 19700
Figure 43. Plot of silvervs. gold for allmassive sulfide deposits, Arizona. Symbols and mine names as in figure 42.
Uppermost dashed, diagonal line is Ag/Au = 10; middle dashed, diagonal line is AglAu =40; lowest dashed,
diagonal line is AgiAu = 100.
1.0
+ o
--. 0.1 s:: �o o '-" :::I < 0.01
1.0 H Ag (oz/ton)
19 Excerpts fro m "Base- and precious-metal concentrations of Early Proterozoic massive sulfide deposits in Arizona--crustal and thermochemical controls of ore deposition;by Ed DeWitt.
Figure 44. Massive sulfide metallic mineral districts and metal zonation patterns ince ntral and northwestern Arizona. Location of Pittsburg-Tonto, Pranty's Cabin, Gray's Gulch, and Bronco Creek districts indicated, but
district names deleted. Number beneath district name =
Au (ozJton); second number beneath district name = Ag
(ozJton); number to right of Au and Ag grades = AgjAu; area in westernArizo na underlain by Mojave-type crust shown by stipple pattern.
Low-Cu High-Pb ----- Ver�e lSO Big Bug \ ;:040 -37 .075 35 , 1.459 ! 2.659 I Mayer I / AguaFria '.;� .046 25"-., 1.159 \1,,, .005 3 J .:, T�-t...r"'\... Zonia 5 --. \� \ .261 , " (low) • . .000 12 .. New River- - _ .001 Kay 8 \ < , .05 8 .- .Lt!�L·007 64' 1 •• 0- �'\ J .425 - I. 34° -1.07--0
20 Exce rpts from "Geologyof Early Proterozoic gold mineralization, alteration assemblages, and geochemistry of the Huron-Victor-Swindler-Montezuma prospects, Yavapai County, Arizona," by P. F. 01Iara andR. C. Long.
Geology of early Proterozoic gold mineralization, alteration assemblages, and geochemistry of the Huron-Victor-Swindler-Montezuma prospects, Yavapai County, Arizona
PATRICK F. O'HARA Kaaterskill Exploration, 691 Robinson Drive, Prescott, Arizona 86303
RONEY C. LONG PegasusGold Corporation, 230 S. Rock Blvd. Suite 30, Reno, Nevada 89502.
ABSTRACf
A series of early Proterozoic quartz porphyries of flanks of major folds duplicate the section, and because limited lateral extent are associated with hydrothermal of probable thinning and thickening of units during alteration and stratabound gold mineralization within the deformation (Anderson and B1acet, 1972c). Dig Bug Group in central Arizona. These quartz porphyries mark the end of a volcanic cycle within the Iron King Formation and are probably the most highly fractionated rocks within the cycle. These quartz porphyries were emplaced along a series of potential growth faults which may have displaced the seawater - seafloor interface downward to the north. Deeper water AZ 69 to the north inhibited the formation of silicification and brecciation within the hydrothermal system because of pressure constraintson boiling and/or the change between lithostatic to hydrostatic pressure. Iron carbonate alteration. in basal rocks of the next volcanic cycle PRESCOTT HUMBOLDT immediately above the stratabound mineralization,
suggested that the hydrothermal system continued AREA OF ...... activity long after the mineralizing event concluded. FIGURE 2
INTRODUCTION 1-17
Metavolcanic and metasedimentary rocks of the Yavapai Series (Anderson and Creasey, 1958) crop out within the area described in this study (Figure 1). These rocks were originally subdivided into the Ash Creek Group and Alder Group (Anderson and Blacet, 1972). Isotopic data led Anderson and others (1971) to replace • the name Alder Group with the Big Bug Group, which • includes all the rocks oC the Yavapai Series exposed in Phoenix the Prescott-Jerome area.
The Big Bug Group is divided into three formations. 0 From oldest to youngest they are: 1) Green Gulch 112 15' Volcanics; 2) Spud Mountain Volcanics; and 3) Iron King Volcanics (Anderson and Silver, 1976). The Green Gulch Volcanics are not present in the area oC this study and will not be discussed. The thickness of the Big Bug Figure 1. Location oC the study area. Group cannot be measured with confidence because of the probability that unrecognized small folds on the
21 Excerpts from "Geology of Early Proterozoic gold mineralization, alteration assemblages, and geochemistry of the Huron-Victor-Swindler-Montezuma prospects, Yavapai County, Arizona," by P. F. O'Hara and R. C. Long.
REGIONAL GEOLOGY
The Iron King Formation are composed of a thick Isoclinal folding obscures the original stratigraphy sequence of metamorphosed, pillowed and amygdaloidal (Anderson and Blacet, 1972; DeWitt, 1976, 1979; andesitic and basaltic flows. Locally the Iron King Anderson, 1978; O'Hara and others, 1978); therefore, the Formation contain thin interbeds of metamorphosed only way to develop a stratigraphy is to fit the lithologic rhyolitic tuff and flow units. The youngest members of units into a fold model. Lack of marker horizons of the Iron King Formation are metatuffs of mixed andesitic adequate lateral extend hinders structural and to rhyolitic composition that crop out in the trough of an stratigraphic analysis in the region. overturned syncline. Near the prospects, there is an extremely varied The Iron King Formation was informally subdivided package of volcanic and sedimentary rocks (Figure 2). into members (O'Hara, 1990) to facilitate mapping for Metavolcanic units · are complexly interlayered and industry. . The area encompassing the Montezuma, indicate that rapid facies changes were characteristic of Swindler, and Huron prospects is underlain by two the protoliths, that potential growth structures existed to members informally called the Boggs and Railroad obscure the stratigraphic relations, and/or that structural members. Both of these members have been further repetition has taken place. subdivided for inclusion on a 1' = 500' map generated for a belt of rocks between Mayer and Iron King mine (O'Hara, 1990).
Figure 2 (below and facing page). Geologic map of the Huron-Montezuma area. Data from O'Hara (1990) and Anderson and Blacet (1972b, 1972c). All Early Proterozoic rock units are within the Iron King Volcanics. Irregular stipple pattern shows area of epidote-sericite + magnetite alteration. Even stipple pattern shows area of aluminosilicatc alteration. Diagonal line pattern shows area of silicification. Small bodies of metachert and Iron-formation shown by thick, solid line (O'Hara, 1987). List of map units:
QTs Quaternary to Tertiary units, undivided Th Tertiary Hickey Formation fanglomerate TKgd Tertiary to Cretaceous granodiorite Xg Early Proterozoic gossan derived from pyrite-rich metavolcanic rocks Xc Early Proterozoic metachert and iron-formation Xvs Early Proterozoic metavolcanic and metasedimentary rocks; includes metamorphosed calcareous sediments, graywacke, andesitic volcanics, and dacite tuff Xes Early Proterozoic metamorphosed iron-rich sediments; not chlorite-rich Xgw Early Proterozoic metagraywacke; contains felsic to intermediate metatuff and minor metachert Xt Early Proterozoic metamorphosed tuffaceous rhyolite and felsic tuff Xf Early Proterozoic metamorphosed felsic volcanics Xq Early Proterozoic metamorphosed quartz porphyry Xfc Early Proterozoic metamorphosed felsic volcanics; containchlorite and pyrite Xff Early Proterozoic metamorphosed fragmental felsic volcanics Xfq Early Proterozoic metamorphosed felsic volcanics and quartzporphyry. Xd Early Proterozoic metadacite porphyry Xap Early Proterozoic meta-andesite porphyry Xa Early Proterozoic metamorphosed andesitic volcanics andvolcaniclastic sediments Xb Early Proterozoic metamorphosed polymictic breccia
EXPlANATION
'?MILE 0 -----··· Seale 1:12,000 Route of field trip Contact: daohed where lnfnntl. clotted when concealed
22 Excerpts from "Geology of Early Proterozoic gold mineralization, alteration assemblages, and geochemistry of the Huron-Victor-Swindler-Montezuma prospects, Yavapai County, Arizona," by P. F. O'Hara and R. C. Long.
Humboldt. Prescott
~
.··-. '.
.. . ! xa :
23 E� cerpts from "Geology of Early Proterozoic gold mineralization, alteration assemblages, and geochemistry of the Huron-Victor-Swindler-Montezuma prospects, Yavapai County, Arizona," by P. F. O'Hara and R. C. Long.
HURON - VICTOR - SWINDLER - MONTEZUMA ALTERATION
PROSPECTS Gold mineralization and ;!!;sociatcd alteratioll A series of quartz porphyry intrusions crop out at the assemblages are characteristically a!;Suciatcd with !;mall top of a steeply dipping sequence of intermediate to felsic felsic volcanic centers in the EJrly Protef07.Uic metavolcanic rocks and interlayered immature metavolcanic belt of central Arizona (O'Hara, 1986). The metasedimentary rocks. Rapid facies changes with felsic metavolcanic rocks are variably altered to sediment dominated rocks on the north side of each assemblages rich in quartz and muscovite. In the vicinity quartz porphyry,suggest that the quartz porphyries were of many mines and deposits, a general increase of emplaced along growth fa ults which facilitated aluminosiJicate minerals takes place downward in the hydrothermal flow and the formation of chemical lower portion of the altered sequence. The sediments in the north flanking basins. This entire rock aluminosilicate minerals are replaced upward package is overlain by a complex mixture of quartz+l-sericite assemblages or quartz dominantby metamorphosed calcareous sediments, graywacke, assemblages (Figure 3). In places, "exhalative" chert andesitic volcanic rocks and dacitic tuff (O'Hara. 1987). flanks the inferred volcanic-hydrothermal vent. In each of seven known or inferred hydrothermal systems near The mineralized quartz porphyries contain very fine the Huron-Montezuma prospect, brecciation (either grained «O.lmm in diameter) quartz phenocrysts as caused by hydrofracturing at depth or explosions onto the opposed to the coarse grained (>O.5mm in diameter) seafloor). pyrite enrichment. and concentration of gold phenocrysts in unmineralized quartz porphyries lower in can be documented. The location of highest gold grades the section. The tops of the mineralized quartz varies laterally and vertically from system to system. porphyries are mound shaped in cross-section (map view Variations in the spatial distribution of gold are probably because of the steep dip of the lithologies). Alteration related to physio-chemical controls such as depth of the and mineralization are associated with the fine grained seawater-sediment interface. and temperature and quartz porphyries forming a series of complex composition of the hydrothermal fluids. hydrothermal-intrusive vent complexes at the seawater seafloor interface (Figure 3). r------, YO UNGER ROCKS
A YOUNGER ROCKS
CHE"'C.l ""ECIPITAT E
OLDER ROCKS 8
3b. Incomplete alteration sequence with silica Figure 3a. Complete alteration sequence. replacement and silica breccia ra cies missing.
24 Excerpts from "Geology and alteration assemblages at the Bluebell Mine, an Early Proterozoic massive sulfide de posit, Yavapai County, Arizona," by Ed De Witt.
Geology and alteration assemblages at the Bluebell Mine, an Early Proterozoic massive sulfide deposit, Yavapai County, Arizona
Ed De Win M.S. 905, U.S. Geological Survey, Denver, CO 80225
OBSERVATIONS In many rc:spects, the Early Proterozoic massive lanthanum, cerium, orynrium to their otherwise standou'd sulfide deposit at the Bluebell Mine near Mayer, list of elements. Likewise, if tourmaline is sufficiently Arizona, is typical of many small ( <5 million-ton) concentrated in the biotite-rich layers, geochemical orebodies hosted by 1.74-1.75-Ga metavolcanic rocks. sampling programs emphasizing boron may prove The orebody is localized at the lower('?)contact of a effective in the search for concealed massive sulfide hydrothermally altered rhyolite and underlying basalt deposits in north-central Arizona. and tuffaceous sedimentary rocks (Lindgren., 1926;; Anderson and Blacet. 1972b). The ore ranges from 20 to Mayer District 80% pyrite and contains much lesser amounts of Located southwest of the Agua Fria district, the Mayer chalcopyrite and arsenopyrite, and minor amounts of district (figs. 1, 17), contains massive sulfide deposits in and sphalerite, galena, and tennantite(?) (Lindgren, 1926; at the contacts of metarhyolite flows with metabasalt and DeWin, 1976) The major gangue is a mixture of quam, meta-andesite (Lindgren, 1926; Tenney,1935; Blacet, 1968, muscovite, and chlorite derived principally from 1985; Anderson and 13lacet, 1972a, 1972b; DeWitt, 1976, hydrothermally altered rhyolite. No feeder pipe cutting 1978, 1979, 1987; Anderson and Guilbert, 1979; O'Hara, through the footwall rocks has been recognized at the 1980; Vrba, 1980; Argenbright and Karlstrom, 1986; Bluebell (De Win, 1979); rather, the altered rocks appear Anderson, 1989a). The district has average to very slightly to be spatially associated with the elongate metarhyolite. low copper and silver grades and an average to slightly high This alteration geometry and lack of a clear-cut pipe gold grade (table 1). Two mines, the Bluebell and DeSoto beneath or peripheral to the orebody is typical of other, (table 6), produced all the ore from the district and have small massive sulfide orebodies near Mayer, such as the very similar metal concentrations. Neither produced lead DeSoto and Hackberry deposits or zinc, and both contain only minor galena or sphalerite In detail, however, the alteration assemblage in (Lindgren, 1926). ore-grade material collected from outcrops, old stapes, The Bluebell mine was the fifth largest massive sulfide and waste piles, is more varied. Particularly noteworthy deposit in the state in terms of tons of ore. The deposit is is the abundance of biotite-rich material containing localized in and at the contact of underlying metabasalt and abundant calcite, disseminated allanite and thin layers overlying metarhyolite (Lindgren, 1926; DeWitt, 1976, rich in tourmaline. Gangue in normal pyrite-rich to pyrite-poor ore may be either: 1979). Both pyrite-rich and pyrite-poor ore is present. Ore I) quartz-muscovite-chlorite-opaque material minerals are pyrite-chalcopyrite-minor arsenopyrite 2) quartz-calcite-opaque material sphalerite-minor galena. Gold correlates well with silver 3) biotite-plagioclase-calcite-muscovite-opaque (fig. 18), resulting in a constant Ag/Au of about 25 over material much of the life of the mine. High gold and silver grades 4) biotite-calcite-tourmaline-allanite after 1920 are a result of mining small quantities of 5) biotite-plagioclase-hornblende-allanite enriched ore (fig. 19). The prominent peak for 1905 data is opaque material a result of estimating pre-1905 production. Silver (and 6) hornblende-biotite-calcite-plagioclase hence, gold) correlates well with copper (fig. 19). opaque material The DeSoto mine (Lindgren, 1926; Blacet, 1968; The presence of biotite-rich gangue that locally DeWitt, 1976, 1979; Vrba, 1980) produced only one-fourth grades into biotitite is perceived as particularly as much ore as the Bluebell, but shared most of its important, as zones rich in tounnaline and allanite are characteristics. Massive sulfide and stringer ore are at the much more common in the biotite-rich layers and contact of underlying metabasalt and overlying biotitite that in any other layers. The biotite-, allanite-, meta rhyolite. Ore minerals are the same as at the Bluebell and tourmaline-rich layers are interpreted to be either mine. Gold and silver are highly correlated (fig. 20). tuffaceous sedimentary horizons of unusual, possibly Ag/Au is constant over the lifetime of the mine. Silver (and alkalic character, or layers formed from extreme hence, gold) is moderately well correlated with copper (fig. hydrothermal alteration of diverse protoliths. 21). A 1904 estimate accounts for half the ore produced at Because allanite characteristically is enriched in the DeSoto, but that estimate is in agreement with metal light rare-earth-elements, geochemical sampling ratios for succeeding years. programs may be able to determine stratigraphic intervals favorable for mineralized material by adding
25 Excerpts from "Geology and alteration assemblages at the Bluebell Mine, an Early Proterozoic
massive sulfide deposit,Yavapai Co unty, Arizona," by Ed DeWitt.
Table 6: Massive sulfide deposit production data, Mayer district [See headnote of table 1 for explanation].
DEPOSIT Ore (') Cu (lb) Pb (lb) Zn(lb) AI (az) Au (az) Cu (%) Zn (%) AI Au (oz/t) A&lAu Bluebell 1.144,603 69.779.084 1.373,.538 54,145 10S (oz/t)1.200 0.047 23 Desoto 237.267 13,896,480 231.266 10.919 2.70 0.977 0.042 2J
TOTAL 1.401.870 83,675,56ol 1,624,804 65.064 2.98 L159 0.046
Figure 18. Plot of year of production vs. silver, gold in Figure 19. Plot of year of production vs. ore, copper, the Bluebell mine, 1903-1930. silverin the Bluebell mine, 1903-1930.
Bluebell Mine Bluebell Mine Year versus Silver. Gold Year Ore, Cu, and Ag grades 3 ---....,...... ------...,.-,---,-,. -- =====vs. ----- ,- 0.15 150r r= =;- T.. TT,. 73 1 \ 25ye arsproduction, 63 � 2S years production, 12° t-��=Jt_� -�====���iH t---It---L=::':':::.J---i'"'c---i 53 I 9OJ.1930 1 0.1 C0 � � � " c: C " 'C I o 0 c: c: 43 90 !.. ! 13+----r--+--�----_,�----�� � " ; ; ! !.10 .. " 33 0( \i :< � E C§J/ 0( 0.05 0 60 t" • � ' ' .. u ", ....i- 1 ./ l'" � 03+------��--��·�'------� �+---�-+--��'/ �------�-+-7��...� I"'� U �------�------+o 03 1900 1910 1920 1930 1900 1910 1920 19�
Ye:1r Year
26 Excerpts from "Geology and alteration assemblages at the BluebellMine, an Early Proterozoic massive sulfidedeposit, Yavapai County, Arizona," by Ed DeWitt.
...� t) � CQ i ....t) CI g J :E i 1 f ... = j i § 1 iu "j .§ 11 i - i." Q, = ] � "§ "� i 1 1i .... :=B 13 li ;... z > .c0 oSt) i Q '5 � 't-i ] = 3 'S B -i -=u � s 0 � � CIoo 0 � � ic 0 � 1 j :a g Q.,CQ a � e III: 11.� "6hu - 0 � 0� [!J[!] � � 0 = Co:)t) :.: . : . ".: . :; ;:�':� �: : Q . ::��:;:;::::' : " : /��i�� f : I •" : : • • • I •
27 Excerpts from "Early recumbent folding during Proterozoic orogeny in central Arizona," by K. E. Karlstrom. Reprinted with permission from Grambling, JA, and Tewskbury, B.J., eds, 1989, Proterozoic geology of the southern Rocky Mountains: Geological Societyof America Sp ecial Paper 235, p. 155, 160, 162, and 163
Early recumbent fo lding during Proterozoic orogeny in centralAr izona
Karl E. Karlstrom Deparrmenr of Geology, No nhem Arizona Un iversity, Flagstaff, Arizona 86011
ABSTRACT
Two generations of folds affected the folded unconformity between the l,750-Ma Brady Butte Granodiorite and overlying Proterozoic Texas Gulch Fonnation meta graywackes and slates in the Brady Butte area of central Arizona. F fo lds are isoclinal and were predominantly northwest-verging recumbent folds prior to1 F2 folding. They occur at scales, with macroscopic fo ld amplitudes exceeding 500 m. F folds were temporallyall associated with transposition of bedding and mesoscopic thrusting1 in meta sedimentary rocks, .and development of mylonitic foliation in both metasedimentary rocks and granodiorite. Both style of structures and asymmetry of fabrics suggest F fo lding accompanied northwest-directed thrusting. F2 fo lds are open to tight and have1 northeast-striking, steeply dipping, axial plane fo liation. Fz fo lds are gently northeast plunging in the Brady Butte area, coaxial with F folds, and the enveloping surface of F 2 folds is subhorizontal. 1 New structural data may have important regional implications. A subhorizontal enveloping surface for F2 folds implies that stratigraphic units and the basal Texas Gulch Fonnation unconformity are repeated across strike in F! fold hinges. Thus, the metased imentary rocks of the Crazy Basin area may correlate with the Texas Gulch Fonnation, and parts of the Spud Mountain Volcanics may correlate with parts of the Iron King Volcanics. However, transposition during F! and rotation of fold hinge lines toward the subvertical F! fm ite stretching axis in areas of high shortening complicate struc tural geometry such that rootless intrafolial fo lds are common.strain Furthennore, Fz fo lds
affected an already transposed SI tectonic layering fo nned by recumbent fo lds and thrusts. The complex overprinting of Fl and Fz on a regional scale make stratigraphic interpretations tenuous more detailed structural, geochronologic, and geochemical data are available. until
INTRODUCTION orogenic cross section can be divided into two major provincesThis (Fig. 1): an older (1,800 to 1,700 Ma) province to the Early Proterozoic (1,800to 1,600 Ma) rocks in Arizona are northwest, underlain by oceanic volcanogenic rocks of the Yava exposed in a northwest-trending band in the Transition Zone, pai Supergroupl. and a younger (1,740 to 1,600 Ma) province to between the Colorado Plateau and Basin and Range Provinces the southeast, underlain predominantly by continentally derived (Fig. 1). band provides semi�ontinuous exposure for more rocks of the Tonto Basin Supergroup and Diamond Rim Intru than 500This km perpendicular to strike of the Proterozoic orogenic sive Suite (Conway and others, 1987; Karlstrom and others, belt. The Transition Zone been affected by Tertiary high 1987). Although the exact geometry and tectOnic history of the angle fa ults of moderatelyhas large displacement, but no post
Precambrian ductile deformation or large Teniary extensional 'This sequence of rocks was the Yavapai by Anderson and strains have been documented, so it is possible to study a cross others The chrooostratigraphicnamed term is replacedSeries in paper by the lithostratigraphic(1971). term '"Supergroup" io acc'"Series�ordance with recommendationsthis of section of Proterozoic crust that been largely undisrurbed the of Stratigraphic Nomenclature (Henderson and has since ca. 1.400 Ma. amendments [0 U.s. Code others, 1980).
28 Excerpts from "Early recumbent folding during Proterozoic orogeny in central Arizona," by K. E. Karlstrom. Reprinted with permission from Grambling, J.A., and Tewskbury, B.J., eds, 1989, Proterozoic geology of the southern Rocky Mountains: Geological Society of America Special Paper 235, p. 155, 160, 162, and 163
cent volcanic rocks because of its position toward the center of a much more complicated deformational geometry than envi the inferred regional anticline cored by the Brady Butte Grano sioned by either worker, as discussed later. diorite (Fig. 4), and based on correlation of the Texas Gulch O'Hara and others ( 1978) and O'Hara ( 1980) were the first Formation with slates exposed in the core of a major ovenumed workers to recognize that deformation in the rocks of the Texas anticline in the Green Gulch Volcanics (Krieger, 1965: Anderson, Gulch Formation, and by inference older rocks, involved multi 1968). Blacet ( 1966) had documented that basal granodiorite ple fold generations and that distribution of stratigraphic units boulder conglomerate of the Texas Gulch Formation uncon was more complex than could be explained by a pattern of formably overlies a nonhern phase of the Brady Butte macroscopic anticlines and synclines. They noted that Blacet's Granodiorite (bb in Fig. 3), which he considered at that time to (1966) map pattern in the Brady Butte area (Fig. 3) suggested be basement to the Yavapai Supergroup. He also showed that a fold overprinting relationships (Blacet had interpreted this map southern granodiorite intrudes the Spud Mountain Volcanics, and pattern to be a topographic effect), and that two generations of he considered this to be a younger pluton. However, when U-Pb mesoscopic folds could be seen in Mule Canyon, at the nonh end zircon dates showed that the two granodiorites were about the of the Brady Butte Granodiorite. This chapter documents the same age (1,750 = 10 Ma), Anderson and others (1971) con macroscopic and mesoscopic geometry of multiple fold genera cluded that they were probably two phases of a single batholith tions in the Brady Butte area (see Fig. 3 for location), and re and that the Texas Gulch Formation must be younger than the evaluates structural and stratigraphic interpretations of the Spud Mountain Volcanics. Anderson and others (1971) no Yavapai Supergroup of the Big Bug block in light of new struc longer considered the Texas Gulch Formation to be part of their tural data. Yavapai Series (Fig. 4). The unconfonnity was apparently be lieved to represent considerable hiatus such that the Texas Gulch GEOLOGY OF A FOLDED UNCONFORMITY Formation did not belong within the 1,800 to 1,750 Ma interval specified for the Yavapai Series. The Brady Butte area (Fig. 5) is very important for under The structural interpretation of Anderson and his co standing the structure of the Yavapai Supergroup. Most of the workers was that the regional folds are entirely upward-facing 3 Yavapai Supergroup of the Bradshaw Mountains consists of len and have subhorizontal plunges on a regional scale. They be ticular and gradational volcanic units, many lacking primary lay lieved that the distribution of stratigraphic units in the Big Bug ering. In contrast, the Brady Butte area contains a mappable Group was controlled by a single generation of upright folds . The unconformity, and metasediments of the Texas Gulch Formation discovery, from isotopic data, that a unit toward the center of an preserve primary structures and fold overprinting relationships. anticline (Texas Gulch Formation) was younger than a unit The preservation of early structures may be due to the location of farther out (Spud Mountain Volcanics) created problems recon this area near the hinge of a macroscopic antiform cored by the ciling structural and stratigraphic interpretations. They proposed massive Brady Butte Granodiorite (Fig. 3). where regional short that major ductile faults and shear zones entirely bound the Texas ening strains were apparently lower than in adjacent areas. Gulch Formation (Fig. 4) and caused this younger unit to be The unconformity, seen at several locations (shown with downthrown along "piercement structures" in the core of the dots in Fig. 5), is marked by basal conglomerate with boulders of regional anticline (Anderson, 1967: Anderson and Blacet, granophyre, granodiorite, mafic volcanics. chen. and quartz in an 1972c). Gilmour and Still (1968) questioned the presence of arkosic matrix. This conglomerate is widespread but is not pres these faults bounding the Texas Gulch Formation. as have other ent everywhere at the contact (Fig. 5), suggesting that the con subsequent workers (DeWitt, 1976; O'Hara. 1980; and this glomerates initially were lenticular debris flows or alluvial chapter). channels and/or that the contact has been tectonized. These basal DeWitt ( 1976, 1979, 1980), working in the area of the Iron boulder conglomerates reach a maximum thickness of about 10 King Volcanics of Anderson and others ( 1971; Fig. 4), recognized m, with lenses of pebble conglomerate also occurring higher in problems with the structural interpretation of Anderson and oth the section. In areas where basal boulder conglomerate is absenL ers (1971 ). DeWitt reponed a preponderance of steeply plunging the unconformity is marked by pebble conglomerates or meta minor folds and mineral and pebble lineations, and he reinter sandstones. Below the contact is highly altered granodiorite in preted the stratigraphy in terms of steeply plunging macroscopic which feldspars have been converted, either panially or com folds. This prompted a discussion from Creasey (1980), who pletely, to fine-grained muscovite and quartz. In places these pointed out that areas outside DeWitt's study area, such as the altered rocks form a gradational zone between less altered grano Brady Butte area. had predominantly shallow-plunging folds and diorite and basal conglomerate or arkose. These intensely altered that it was these folds that controlled regional stratigraphy. This granodiorites may represent regolithic material, as is suggested by controversy can be reconciled with new structural data that show their association with the unconformity. Alteration of feldspars may also have accompanied mylonitic deformation of the grano 'Shackleton ( 1958) defined fold "facing" as the younging direction seen m diorite (Knipe and Wintsch, 1985). fold hinge areas. Combmed 1.1.1th the concept of envelopmg surface (Hobbs and other;. 1976). facmg is useful for reconsuuctmg mat1graphy in isoclinally folded The importance of the unconformity from a structural view and trans~d sequen=. Folds can face up or down or in any compass direcuon. point is that it is a marker horizon, across which younging is
29 � � ...
�en �S:��t:;> a.. 0 � tT1 0 c: Ii) S , ° ' ...... �rt1 0 . 112 2 " ° ���c: ... � .. . . An 22' 30" . J . 34 .'.1111 .... "...... < ...... ,,' < �:J � �� G) OJo... (!) l. S � o � c:: O(!) ::nS,
<9,O �� {g g- !!:!. -4 :J � / :::: ::::::"" :U. . . ":. 80�...... ,, � .. . • ,.. · .. .. v ..." . . .. :0.... ':::::: t::::: Figure Geologic map or the Urady Ilullc area showing the trace or the basal Texas Gulch Formation unconrormity.5. See Figure location. 3 ror � FIGURE 5 EXPlANAliON � contocl : �nown, approKimale, inferre d Ter tiary (?l felsic dike �I/) [Z] from air photos �---.-. ��;j)i�t:r UZ Q ° (Ii.:ElTlo � gray slate s S� � fault : known , o p proKim a t e cn��c: � , Cl.... ,.-- -- -- bedding olld transposed bedding ° � . � � alaskitic gron:>dior lle bO oen ::ns � ...- <9.o ·� � g- �s 51 foliation a :::J t:3 Brody Butte Granodiorole f2!illl] ,J.- \ ....., cleavage C/>(Oib8'-... :::J ...... : 11 52 O �QS: u. minor fold ans showing plan view �. . � s· rhyoli tic luff �'O en "tI _. (JQ _:> o <10 ''Y) sketch of folded surface � a s o. u.Q: � \'. . ='_\ 'O� .0) '< ";���:i'�::;:;;;c�;�;;� 1\) 0" .. . . Tr Tr T minor fold axes So and SI (dots) and foliation (SI and S2 ) S2 cleavage F2 � - fold axes ( x) in Te xas In granodiorite Gulch Formation Figure Lower-hemisphere equal-area projections of fa hriL: clements in the Brady BUlle area. 6. DAY 2 The second day of the field trip will be somewhat more diversethan the first. initial stop will be near the old town of Cordes, where we will have an overview of stratigraphy and structure inthe southernOur part of the Bradshaw Mountains. During the moming, participants can choose between an ore deposits-related stop at the Golden Belt Mine, a middle Tertiary low-angle gold-rich vein deposit near Townsend Butte, or a structural stop west of Cleator in pelitic metasedimentary rocks adjacent to the 1.70 GaCrazy Basin Quartz Monzonite. The ore deposit stop at the Golden Belt Mine will discuss the origin of middle Tertiary low-angle silver-rich vein systems. The stop west of Cleator will discuss the structural relationships of emplacement of the Crazy Basin Quartz Monzonite andthe formation of regional fabrics in the surrounding country rocks. Road Log and Field Trip Guide By Ed DeWitt Day 2 - Morning: Mayer, Arizona, to Cordes, Arizona Road Log from Mayer, Arizona, to Cordes, Arizona: 2.8 Crossing Big Bug Creek again. Small gold placer 15.7 miles. operation on the rigbt side of the higbway. Cwnulative 3.0 Roadcuts in hematite-stained and altered Mileage metarhyolite tuff. These altered rocks are the 0.0 Circle K Store, Mayer, Arizona. Proceed south on southern extension of extremely altered Arizona State Highway 69 toward Phoenix. metavolcanic rocks in the Copper Mountain area to the north. Tertiary Hickey Formation 0.7 Black Canyon Mobile Home Sales area on the right. covers the metavolcanic rocks on the right side Turnoff to the Bluebell Mine is on the right. of the highway (fig. 2). 1.5 Outcrops on the left at 10:00 are ribs of fe rruginous 3.6 Most ofthe roadcuts from here to thejunction with metachert that protrude above tuffaceous Interstate Highway 17 are in Hickey Formation. metavolcanic rocks. Some of the metachert and iron-formation defme large, north-closing fo ld 4.2 Forested, flat-topped peaks on the horizon at 11:30 structures to the east of Mayer (fig. 2). to 12:00 are in thePine Mountain area (Canney Outcrops on the right that we are driving past and others, 1967). The high plateau near Pine are tuffaceous metarbyolite and pelitic Mountain was one of the first areas in the metasedimentary rocks. Jerome-Prescott region to be designated a Primitive Area. Small beltsof mafic 1.9 Crossing Big Bug Creek. metavolcanic rocks arepreserved within a large granite to granodiorite complex whose 2.1 Outcrops on both sides of the highway are description is similar to the tonalite of Cherry tuffaceous metavolcanic and metasedimentary (DeWitt, 1989). Paleozoic strata overlie rocks. Prominent lens of ferruginous metachert Proterozoic rocks, and all are covered by noted in this roadcut. Near end of roadcut extensive basalt flows of the Hickey Formation. metarhyolite tuff and quartz porpbyry predominate. 5.0 Panoramic view to the right shows Towers Mountain on the far right., high peaks in the basin near 2.3 Crossing Big Bug Creek. Outcrops on the rigbt are Crown King to the left, and peaks in the tuffaceous metarbyolite exhibiting sericitic Horsethief Basin area to the left of Crown King, alteration and minor chloritization. Minor iron at about 2:00to 2:30. Much of the southern formation is interbedded with the metarbyolite. Bradshaw Mountains in the Horsethief Basin Hills to the left are predominantly metarhyolite area is made up of the 1700 Ma Crazy Basin containing minor amounts of meta-andesite. Quartz Monzonite (Karlstrom and Conway, 1986; DeWitt, 1989), the rock that forms the 32 bouldery weathering topography noted even Towers Mountain at 9:00. Crown King in basin from thisfar away. skyline at 8:30. Horsethief Basinon skyline aton 8:00. A Laramide stock at Crown King (Jaggar and Palache, 1905; DeWitt, 1976) and a 14.0 Crossing small creek. Metavolcanic strata northeast-striking system of granodiorite to concealed by basalt flows and sedimentary rhyolite dikes and Laramide veins are host to rocks of the Hickey Formation (fig. 2). the Tiger metallic mineral district, which is centered on Crown King. The district isone of 14.5 Stop sign. Old town of Cordes. Turn left on#259 the larger Laramide base- and precious-metal toward Cleator. districts inthe Bradshaw Mountains. Approximately 14 major mines and numerous 15.0 Cattle guard smaller mines have produced more than 270,000 tons of zinc- and gold-rich ore . The 15.7 Top of ridge. Take trail to left. New River stock has an evolved phase that contains breccia Mountains at 10:00. Towers Mountain at 1:00. pipes and disseminated molybdenum. In all aspects, the district strongly resemblesthe STOP 4. Park vehicles carefully possible; try to Copper Basin district west of Prescott. make sure all areas off the road,as this turn is sharp and hard to see around. Atas this stop we 7.7 Cordes Junction and intersection with Interstate will discuss various interpretations of the Highway 17 to Flagstaff and Phoenix. geology of the southern Bradshaw Mountains, Turn right onto the entrance ramp for southbound including to what degree the Shylock fa ult zone J- 17 toPhoenix. At 12:00 in the fo reground are does or does not continue to the south from this brown, granitic-weathering hills composed of point., and what role do high strainzones, such Bwnblebee Granodiorite. the Shylock, play in the evolution of the asEarly Proterozoic deformation in the state . 8.6 Bridge over Big Bug Creek. First roadcuts are in a mixed variety of rocks including foliated After this stop, return to the main road, granodiorite, metarhyolite, and some meta turn left, and continue toward Cleator and andesite. Outcrops to the right on the ridge are Crown King. predominantly metarhyolite. In the foreground is a plutonic rock describedby Anderson (1972) Road Log fr om Cordes, Arizona, Golden Belt to as quartz diorite porphyry. Chemically and Mine: 4.3 miles mineralogically the rock strongly resembles the Brady Butte Granodiorite, and is informally Cwnulative called the granodiorite of Big Bug Creek Mileage (DeWitt, 1989). 0.0 Crest of ridge, 0.7 miles southwest of Cordes. Tum left onto main road toward Crown King. 10.3 Crest of small divide. Panorama ahead shows gently dipping basalt flows on Black Mesa and 0.2 Descending grade toward Townsend Butte and Perry Mesa. In the distance are the New River Golden BeltMine. Contact of Badger Spring Mountains. Outcrops on both sides of the Granodiorite, a leucocratic, coarsely porphyritic highway are Bwnblebee Granodiorite. Oarge phenocrysts of quartz), massive to strongly foliated intrusive that extends south 11.3 Exit 259 to Crown King and Horsethief Basin in toward the Black Canyon area the Bradshaw Mountains on the west and the . Bloody Basin area in the New River Mountains 0.9 Cattle guard on the east. Take exit ramp. At stop sign, turn right toward Crown King. 1.6 Y in road; stay to right on #259 toward Crown King. 12. 1 Cross pipeline. Driving through border phase of 2.5 Stop sign. Stay to right on #259. Bwnblebee Granodiorite. 3.0 Trail to left leads to Silver Cord Mine, a small, low 12.5 Cross contact of Bwnblebee Granodiorite on east angle, high-grade silver vein famous for its and metavolcanic rocks on west. specimens of wire silver. 12.8 Trails lead to the right and left. Stay on main road. 33 3.4 Trail to right; stay on main road, which bends to the Mayer. Road now leads to Bluebell Mine left. through pelitic metase&mentary rocks. 3.8 Cattle guard and Prescott National Forest boundary. 1.9 Cleator, Arizona. Continue on main road, which Golden Belt and Golden Turkey mines straight follows bed of narrow gauge railroad that ahead. Dwnps of an unnamed massive sulfide terminated at Crown King and serviced many of pro.spect in the Kay district. on the left at 9:00. the laramide vein deposits in the Crown King area. Continue through pelitic metase&mentary 4.1 Crossing Turkey Creek rocks to stop 5B. Road to the left, just past most buildings, is to the French Lily Mine. 4.3 Tum left on road to Golden Belt Mine. Park cars on waste dump. 2.9 Turnoff to the right leads to the DeSoto Mine, the southernmost massive sulfide deposit in the STOP SA. Golden Belt and Golden Turkey Mines. Mayer metallic mineral district (DeWitt, this These middle Teniary, low-angle, precious volume). The DeSoto mine produced 300,000 metal-rich deposits are in the Black Canyon tons of ore that averaged 3.6% Cu, 0.056 oz/ton metallic mineral district. which produced about Au, and 1.24 oz/ton Ag (DeWitt, 1976; this 265,000 tons of ore from low-angle fractures volume). and from veins adjacent to basalt dikes. Most of the production has come from the Golden Spectacular, softball-size andalusite Turkey and Golden Belt mines. Aspects of the and golfball-size staurolite crystals are exposed geology to be discussed at this stop include the in pelitic metase&mentary rocks along the road origin of the low-angle veins and their near the crest of the hill at 2:30 (De Witt, 1976; relationship to the overlying, flat, and Argenbright, 1986). undeformed cover of basalt flows and sedimentary rocks of the Hickey Formation. 4.5 Bridge over Middleton Creek. Ore from the DeSoto Mine was trammed 1400 feet vertically to this When finished at the stop, return to point on the narrow gauge railroad. Some Cordes and the Horesthief Basin interchange on towers of the tram are visible from this point. 1-17. Once across the bridge, tum to the left and park cars on the flat area off the roadway. Approximate Road Log from Golden Belt Mine to stop SB west ofCieator, Arizona: 4.5 miles STOP 58. Early Proterozoic pelitic metasedimentary rocks and 1.70 Ga Crazy Basin Quartz Cumulative Monzonite. Stop will discuss relationships of Mileage intrusion of the Crazy Basin body and regional 0.0 Golden Belt Mine. Tum left onto road #259 toward fabrics in the pelitic metase&mentary rocks. Cleator. Driving through massive quartz porphyry metarhyolite. When finished, return to Cordes and to the HorsethiefBasin interchange on 1-17. 0.4 Trail to left is old mining road that leads to south of Golden Belt Mine. Road Log from Horsetbief Basin Interchange on 1-17 to Sunset Point Rest Area on 1-17: 6.8 miles 0.5 Ferruginous metachert crosses road. Cumulative 0.7 St. Johns Mine on right. Driving through mixed Mileage meta-andesitic tuff and pelitic metasedimentary 0.0 HoresthiefBasin Interchange (exit259) on 1-17. rocks. Crossing Cleator shear zone of Darrach Tum right toward Phoenix. (1988). 0.4 Panoramic view of the central and southern 0.9 Contact of pelitic metasedimentary rocks that Bradshaw Mountains on the right. Most of the continue from here to Cleator, and to stop 5B high country visible from here at 3:00 is west of Cleator. underlain by two phases of the Crazy Basin Quartz Monzonite (Anderson and Blacet. 1.8 Road to right follows bed of narrow gauge railroad 1972c). The early, syntectonic phase is a fme that originally went to Bluebell siding and to medium-grained, equigranular, highly flow 34 foliated to tectonically foliated two-mica granite regional foliation and isoclinal folding in the (DeWitt, unpub. data, 1990). The late phase is Prescott region therefore took place between late- to post-tectonic (in the interpretation of 1720 and 1700Ma (Anderson. 1987; Karlstrom DeWitt, 1987) and is the coarse-grained. locally and Conway, 1986). pegmatite-bearing two-mica granite that is locally flow foliated and boudinaged near Crazy 4.7 To the right at about 9:00are iron-formation and Basin. Conway and others, (1989) interpret the ferruginous metachert lenses protruding above late phase to be syntectonic. The late phase is altered meta-andesite and metarhyolite in the responsible for much of the amphibolite facies Black Canyon schist belt. The Crazy Basin metamorphism in the southern Bradshaw Quartz Monzonite forms the main mass of the Mountains. No economic pegmatite deposits Bradshaw Mountains west of the schist belt. are iatedassoc with the granite, but tungsten veins in the Tussock metallic mineral district on 5.6 View backto the right at 4:00 isof many of the the southwest side of the granite may be related distinctive Early Proterozoic rock units in the to late quartz veins associated with the granite. Bradshaw Mountains. Highly fo liated metarhyolite forms the light rocks in the Black Much of the high country southwest of Canyon schistbelt, and is especiallyobvious on Horse.thief Basin is underlain by the Townsend Butte, the conical peak on the north granodiorite of Lane Mountain (De Witt, 1989), side of the road to Cleator and Crown King. a pre-tectonic highly foliated leucocratic body that resembles the Brady Butte Granodiorite. Meta-andesite and the quartz diorite of Bland are the dark rocks in the schist belt. 1.5 Roadcuts in hematite-stained Badger Spring Light rocks in the middle distanceare pelitic Granodiorite. metasedimentary rocksnear Cleator. Mafic metavolcanic rocks are the dark band beyond 2.1 View down and to the right through canyons cut into the pelitic unit. The Brady Butte Granodiorite Tertiary fanglomerate is of Bland Hill, which is forms an impressive ridge extending south from underlain by the 1.72 Ga quartz diorite of Bland Brady Butte, the conical peak directly over the (Jerome, 1956; Bowring and others, 1986)}, a top of Townsend Butte. On the horizon are the granodiorite similar in composition to the forested slopes of the high Bradshaw Bumblebee Granodiorite. The quartz diorite of Mountains, underlain by metabasalt and gabbro Bland extends south along the Black Canyon that is well exposed on the slopes of Mount schist belt and forms a major pluton in the Union. the high peak just to the right of Brady western New River Mountains. Butte. 3.4 Exit 256 for the road to Badger Spring. This road View to the right at 3:00 is of Bland provides access to the Richin mine on the Hill and the quartz diorite of Bland in the east side of the Interstate, aI; �:lr2a ly Proterozoic? foreground and the DeSoto ivemass sulfide quartz vein at the eastern edge ofr Black Mesa. deposit on the ridge leading to Crown King in The mine is on the edge of an 800-ft-deep the background. canyon formed by the Agua Fria River. Other mines in the Richinbar district are farther south 6.8 Turnoff to the Sunset Point Rest Area. Exit here for along the highway near Black Canyon City. lunch. Roadcutsare in basalt flows of the Hickey Formation for the next 8 miles. We are on the western edge of Black Mesa, which iscapped by basalt flowsthat are 4.2 At 2:00in the valley bottom is the old town of probably correlative with the Hickey Formation Bumble Bee . Bland Hill and the low country to farther to the north. The youngest flows in the the south of Bumble Bee is underlain by the Hickey near Cordes Junction are about 11 Ma quartz diorite of Bland. All of the pluton is (McKee and Anderson. 1972). The top flow on extensively fo liated, even those parts in the Black Mesa is probably of this general age, and New River Mountains. The western margin is may have been derived from Joes Hills, a locally mylonitic (Jerome, 1956; Winn. 1982). prominent shield volcano to the east across the Deformation of thequartz diorite took place at canyon of the Agua Fria River. Middle Tertiary the same time as regional metamorphism and basalt sources are mostly northwest-trending deformation of the metavolcanic and feeder dikes (DeWitt, unpub. mapping, 1990). metasedimentary sequences. Much of the After lunch, return tosouthbound 1-17 35 toward Phoenix. Day 2 - Afternoon: Sunset Point Rest Area on 1-17 to southern New River Mountains Road Logfr om Sunset Point Rest Area on 1-17 diorite of Bland. Onthe right are the striking to southern New River Mountains: 18.3 miles outcrops of felsic metavolcanic rocks and iron formation along the Black Canyon. Cumulative Mileage 2.8 Exit 248 toBumble Bee provides to the 0.0 SunsetPoint Rest Area on 1- 17. Returnto Interstate Black Canyon and the steepaccess eastern side of the 17 and continue south toward Phoenix. Crazy Basin QuartzMonzonite. All outcrops along the highway are foliated plutonic rocks. 0.2 On the left at 10:00are high peaksof the New River Tertiarytuff aceous sedimentaryrocks and Mountains. Except for the Tertiary basalt lacustrineunits are locally apparent beneaththe source on Squaw Mountain (fig. 3), all high basalt flows. peaks are underlain by -1.7 Ga rhyolite, ash flow tuff, columnar-jointed rhyolite, and 3.7 Deep roadcut in meta-andesite. Slump block of subvolcanic granophyre related to the rhyolite Tertiary basalt and sedimentary rocks to the left (Maynard. 1986; DeWitt. 1987, unpub. of the Interstate. mapping, 1990. This rhyolite sequence is very similar to 1700 Ma rhyolitic ash flows in the 4.9 Town of Black Canyon City ahead. Dumps of the Tonto Basin area (Conway, 1976; Conway and Kay mine, the largest massive sulfide deposit in others, 1983), and to the Red RockRhyolite in the Kay district, are at 12:30, aboutfour miles the Mazatzal Mountains (Wilson, 1939; away. No large mines are located in the Kay Ludwig, 1973). Large rhyolite columns and district; only 2,500tons of ore have been miarolitic cavities in the rhyolite indicate that produced from the district. Most of theore these rocks in the central part of the New River came from the Kay mine, which averaged 5.8% Mountains have not been strongly deformed or Cu, 0.3% Ph,0.06 oz/ton Au, and 1.0 0z/ton metamorphosed. Ag. Small mines and prospects in the Kay district extend north from the Kay mine to the The same columnar rhyolite and ash Great Republic mine near Townsend Butte east flow tuff, and older Early Proterozoic rocks, of Cleator. have been regionally deformed and metamorphosed along the eastern face of the 5.5 Roadcuts on the left expose Tertiary lacustrine New River Mountains, in and adjacent to the deposits (fig. 3) that are cut by northwest Moore Gulch shear zone (DeWitt, unpub. trending normal faultswith minor offset These mapping, 1979; Maynard, 1986; Karlstrom and faultsare the northernmost indicators of Conway, 1986). This shear zone is one of many Miocene extension so commonfa rther south. zones of high strain in the Proterozoic terrane of One-quarter mile ahead. roadcutis in foliated central Arizona. quartz diorite of Bland. 1.2 Roadcuts are in basaltflows. Interstate Highway 17 6.9 Exit 244to Black Canyon City. Black Canyon cuts down through the western side of Black Greyhound Park on the right. Bold outcrops on Mesa and descendsinto the Black Canyon. the skyline to theright are theCrazy Basin Quartz Monzonite. 1.6 At 12:00 are highly foliated outcrops of the quartz diorite of Bland. From a distance the deformed 7.4 Prominent finger of rock at 9:00is remnant of pluton appears to be a metavolcanic or Tertiary basalt resting on lacustrine units. metasedimentary rock. Metavolcanic rocks Depending on thesun angle, Tertiary basalt at crop out about one mile west of the Interstate. 9:00on the horizon can be seen extending three-fourths of the way up the crest of theNew 2.0 Strongly fractured outcrops on the left are the quartz River Mountains. Inferred. northwest-trending 36 feeder dike is beneath Squaw Mountain. undefonned rhyolite and ash-flow tuffin central New River Mountains (Maynard, 1986; 8.3 Bridge over the Agua Fria River, which has cut a Anderson, 1989). deep canyon through the basalt on Black Mesa, to the left. Dump of the Kay mine on the right 17.5. Cross New River. Drive through foliated at about 2:30. metarhyolite for 0.7 miles. next 9.4 Exit 242 to RockSprings and Black Canyon City. 18.3 Largequarry on right in hematitic wacke and One-quarter mile farther south areroadcuts in siltstone (fIg. 3). Park in and around the quarry. Tertiary lake deposits. To the north, the Tertiary basalt and lake deposits have not been STOP 6. SouthernNew River Mountains. Stop here extensively faulted. In roadcuts to the south. will review stratigraphy of the New River however, are the fIrst large nonnal faults to cut Mountainsand discuss the extent and regional these rocks. importance - or lack thereof - of the Moore Gulch shear zone. Undefonned and defonned 11.2 Roadcut in the northbound lane of 1- 17 is in equivalents of the rhyolite and ash flow tuffof slightly fo liated quartz diorite of Bland. Small the central New River Mountains will be roadcuts in this lane are also in quartz diorite or visited, will the older metasedimentary and a combination of quartz diorite and metarhyolite metavolcanicas strata to the eastof the shear zone. (fig. 3). 12.3 Crossing bridge over Little Squaw Creek. The crest of the New River Mountains ison the left. Early Proterozoic metabasaltand gabbro that are older than the ridge-capping 1.7-Ga rhyolite are exposed to the west of the Moore Gulch shear zone (fig. 3). The Orizaba mine, developed in meta-andesite and metatuff, contains the southernmost massive sulfide deposit in the Prescott-Jerome area. The mine produced about 30,000 tons of ore that, during copper- producing years, averaged 4.1 % Cu, 0.42 oz/ton Ag, and 0.013 oz/ton Au. (DeWitt. this volume) 13.2 Bridge over Moore Gulch. Table Mesa two miles ahead. Roadcuts ahead are in lacustrine deposits and mudstone. 15.3 Nonnal fa ults exposed in roadcuts. Most lake deposits dip at low angles to the south. but some dip degrees to the north and have been rotated40 by nonnal fa ults. 15.8 Exit 236, Table Mesa Road. Take exit and cross over the Interstate to the east. Follow gravel road into the southern part of the New River Mountains. Driving through Miocene lake bed deposits and terrace gravels. 16.7. Y in road. Stay to left. Right fork goes to Tee Ranch and is a private road. Just ahead is a fence and gate. Please be surethat the gate is shut after the last car goes through. 17.4 Outcrops are foliated, sericitized, and mineralized metarhyolite tuff that is equivalent to 1.7 Ga 37 Figure 3 (below and two following pages) . Geologic map of the New River Mountains area. Data from DeWitt (1987, un pub. mapping, 1990) , Anderson (1989) , Jerome (1 956), Maynard (1986) , Jagiello (1987) , and Reynold (unpub. mapping, 1990) . EXPLANATION D� Quaternary units, undivided Contact D I QTU I Quaternary and Tertiary units, undivided Fault . � Tertiaryvolcanic and sedimentary rocks Route of field trip YX IIIIIIIIIIIIII!!III I g I Granite of Magazine Gulch Stop number .� Metasedimentary and metavolcanic rocks I Xps I Phyllite and slate I xrhyl Rhyolite, metarhyolite, and ash-flow tuff � Granite to granodiorite Quartz Diorite of Bland � o 2 3 mi Pelitic metasedimentary rocks � o 2 3km Xgb Gabbro I I Scale: 1:100,000 Metachert and iron-formation � xgW Metagraywacke and meta-andesite I I Base from U.S. Geological Survey Metavolcanic and metasedimentary rocks Bradshaw Mountains, 1981 , and . � Phoenix North, 1988 Metarhyolite . � Metadacite and meta-andesite � Metabasalt and meta-andesite � 38 To Phoenix R. 2 E. 39 Fi 3 E. -...�. -/-:. :: . ,.��;� .�§ � -./- > .' - 1;>;g �' , 'N-AII " � l 0 N-, .. ::,,,-�- -:..:: , '':'��, ;��,� . (' ___ J .� _ -, -, ,.-- � -... - ' --" . �-... -�. -'-. �---:.''''��:--� < . - >,'-, ..... ;:.>. XrlIy '-' -" - '- ,T�0���§ .- :' --�..p (I :i I �'.=---;. 1.0t-= . s-; / R. 3E. 40 At the end of thisstop, the field trip is 4.3 Exit 232 to the village of New River. On the left is over. Return via the dirt road to the Table Mesa Gavilan Peak. All the low country to the left is Exit on 1- 17. The road log continues south to underlain by Early Proterozoic tuffaceous New River. metavolcanic rocks. End of road log. Road Log from Table Mesa Exit on 1-17 New to River: 4.3 miles Cumulative Mileage 0.0 Table Mesa Exit on 1- 17. Cross over 1- 17 and take southbound ramp toward Phoenix. 0.6 Roadcut in river gravel deposits. To the right, about 4 miles west, is Wild Burro Mesa, capped by middle Tertiary basalt and cut, to the south, by northwest-trending nonnal faults. 1.6 Outcrops on the right are Tertiary rhyolite tuff. Deep roadcut ahead is in fe lsic tuff and rhyolite cut by nonnal faults that dip to the north. Roadcut contains at least two nonnal faults that dip to the north at about 45 degrees. 2.2 Conical butte at 10:00is Gavilan Peak, elev. 2,980 ft, which is a dacite dome (Jagiello, 1987), about 26 Ma (fig. 3) 2.3 Roadcuts in Early Proterozoic metarhyolite tuffthat may be equivalent to rhyolite and ash flow tuff of the central New River Mountains (Anderson, 1989). Metarhyolite is overlain by Tertiary to Quaternary river gravels. Metarhyolite tuff is very sericitic and iron-stained. New River Mesa visible slightly behind and to the left at 8:00. The mesais capped by 14 Ma basalt, but lower flows that are inter ed with lacustrine units d and tuffaceous bedsrc as old as 22 Ma (Gomez, 1979). 3.0 Outcrops to the left beneath the veneer of river gravel are of sericitir.ed metarhyolite and metamorphosed volcaniclastic rocks. 3.3 Outcrops and flat area to the right of the highway are composed of gray and purple slate and iron stained sericitic metarhyolite tuff similar to that in the southern New River Mountains visited at stop 6. The gray and purple slate is very distinctive of 1.72-1.70-Ga metavolcanic rocks in the Cave Creek area north of Phoenix (Anderson, 1987; 1989) and the Slate Creek Divide area in the Mazatzal Mountains (Ludwig, 1973). Roadcuts are in gray slate that is interbedded with fm e-grained metatuffand volcaniclastic metasedimentary rocks. 41 NOTES 42 E:�cerpts from "Geologyof the Golden Belt Mine area, Black Canyon metallic mineral district, Arizona," by D. E. Wahl, Jr., and P. F. 01Iara. Geology of the Golden Belt Mine Area , Black Canyon Metallic Mineral District, Arizona David E. Wahl , Jr . Consulting Geologist, P.O. Box 10758 Scottsdale, Arizona 85271 Patrick F. O'Hara Kaaterskill Exploration, 691 Robinson Dr . Prescott, Arizona 86303 ABSTRACT The Golden Belt mine and adj acent Go lden Turkey mine lie at the northern limits of known mineralization assoc iated with low- angle vein systems of the Black Canyon metallic mineral district . Both mines are developed on an east-northeast-trending vein system which dips approximately 15 to 22 degrees to the south- southeast . Black Canyon metallic mineral district veins typically are narrow, banded, brecciated , low-angle , quartz-rich systems which contain galena , chalcopyrite, pyrite and sphalarite as principal sulfide minerals . The less than I-foot to 4-foot- thick veins cross cut foliated Early Proterozoic metamorphosed volcanic , volcaniclastic and sedimentary rocks . Wallrock alteration locally intens ifies with depth , and includes argillization, iron staining, and minor development of quartz stockworks veining . Underground sampling and analysis of production records indicate that Golden Belt and Golden Turkey mines ore average grade was approximately 0.12 oz/ton gold and 3.00 oz/ton silver . Approximately 250,000 tons were mined from the interconnected Golden Belt and Golden Turkey mines . Much of this ore was mined from very shallow underground workings . Two distinct types of mill tailings were also investigated 43 Excerpts from "Geologyof the Golden Belt Mine area, Black Canyon metallic mineral district, Arizona,"by D. E. Wahl, Jr., and P. F. O'Hara. at the Golden Belt mine . The most extens ive tailings pile contains approximately 45, 000 tons of material believed to have been mined from the Golden Belt mine . A second , distinctly different tailings accumulation contains approximately 15 , 000 tons of material which is rumored to have originated at the Gladiator mine north of Crown King . Although both tailings piles are gold anomalous , they currently appear to be subeconomic due to difficulties in further recovery of metals from the piles . INTRODUCTION Wilson and others (1967) report that ore was located at the Go lden Belt mine in 1873, and a 50 tpd mill was active in the early 1930 's. Ma jor reported developments in the Golden Belt mine include an 800 feet incl ine shaft and hundreds of feet of stopes and drifts (Wilson , et al ., 1967) . Underground workings of the Golden Belt mine connect with stopes and drifts of the Golden Turkey mine to the south . Recorded production for the two inter-connecting mines is approximately 129,500 lbs . of copper , 791,000 oz . of silver , 28, 900 oz . of gold and 3,347,000 lbs . of lead from 243, 300 tons of ore (Az . Geol . Survey , unpub . data 1990, calculated by Ed DeWitt ). Much less ore was also produced from the Silver Cord and Gold Crown mines near the south end of the Black Canyon metallic mineral district. Historic mining efforts at the Go lden Belt and Golden Turkey mines were concentrated on a sulfide-bearing quartz vein system with an aggregate quartz vein thickness of less than 1 foot to local maxima of approximately 4 feet . Sheared, argillized, iron- 44 Excerpts from "Geology of the Golden Belt Mine area, Black Canyon metallic mineral district, Arizona,"by D. E. Wahl, Jr., and P. F. O'Hara. SURFACE INVESTIGATIONS Minimal surface studies conducted on the 4 lode claims of the Golden Belt property indicate that narrow, low-angle, south- southeast-dipping qu artz veins containing precious metals exist at several locations (Wahl , 198 9) . The best of 10 surface samples indicate that a 2-foot-thick, low-angle , quartz-iron oxide vein locally contains 0.342 oz/ton gold and 4.81 oz/ton silver . Surface vein development and alteration of felsic to intermediate schistose me tavolcanic wa llrocks are not as intense as that observed in Golden Belt stopes . Subvertical quartz segregations that parallel regional foliation are not mineralized . UNDERGROUND EVALUATION Underground workings of the Golden Belt mine were examined to determine the feasibility of a small open pit between the Golden Belt dec line portal and Turkey Creek. The mineralized fracture-vein system exposed in Golden Belt workings lies at shallow depth and dips subparallel with the land surface toward Turkey Creek . Thus , the potentially mineralized fracture-vein system could be excavated with a relatively low stripping ratio . Twenty- four samples were collected from Golden Belt underground workings to test the gold and silver grade of quartz veins and sheared, altered schist adj acent to the veins . Seven samples , averaged for their sample length , of select quartz sulfide veins indicate 0.465 oz/ton gold and 3.11 oz/ton silver . 45 Excerpts from "Geology of the Golden Belt Mine area, Black Canyon metallic mineral district, Arizona," by D. E. Wahl, Jr., and P. F. O'Hara. Vein thicknesses for those samples range from 0.5 to 4 feet . The highest grade assay (0.868 oz/ton gold and iO .31 oz/ton silver ) came from a 3.5-foot-thick vein preserved in a small pillar within the main Golden Belt stope area . Not all Golden Belt workings could be reached due to caving and flooding . Seventeen samples tested sheared , altered schist adjacent to the quartz-sulfide veins over widths of 2 to 6 feet . Averaged assay grade is 0.055 oz/ton gold and 0.36 oz/ton silver . Best values in the schist appear related to areas of highest iron staining and development of hairline quartz-lined fractures . Averaged values for all Golden Belt underground samples is 0.120 oz/ton gold and 0.80 oz/ton silver . Averaged production ore grade of the Golden Belt and Golden Turkey mines is 0.12 oz/ton gold and 3.25 oz/ton silver . Samples collected by Wahl (1989) were all taken above water level . Flooded portions of the mine apparently are more silver rich, perhaps as a result of secondary enrichment at and below the water table . Material of approximately 0.12 oz/ton gold and >1.00 oz/ton silver appears to have been contained within a fairly continuous tabular slab 6 to 8 feet thick prior to undergound mining operations . Such a thickness of ore may well be economic under low stripping-ratio , open-pit mining conditions . Unfortunately, the Golden Belt vein and mineralized country rock have mostly been mined out . Old stope maps underestimate the extensive stopes within workings of the Golden Belt mine . 46 Excerptsfrom "Geologyof the Golden Belt Mine area, Black Canyon metallic mineral district, Arizona," by D. E. Wahl, Jr., and P. F. O'Hara. Figure 2. Location map of principal mines of Black Canyon metallic mineral district . ' I ,�··,Turkey Creek '-\ \ \ / "-....To wnsend Butte � Cleator / USFS 259 x GOLDEN BELT GOLDEN TURKEY .! MINE MINE X ( " .�:' . 1000- ' I X SILVER CORD MINE 47 Excerpts from "Tectonic and magmatic contrasts across a two-province Proterozoic boundaryin central Arizona," by C. M. Conway, K. E. Karlstrom, L T. Silver, and C. T. Wrucke. Reprinted with permission from Davis, G.H., and Van denDolder, EM., eds., Geologic diversity of Ariz ona and its margins; excursions to choice areas: Arizona Bureau of Geology and Mineral Technology Sp ecial Paper 5, p. 158, 159, 160, 169, and 170 Te ctonic and MagmaticContrasts Across a Tw o ..Province Proterozoic Boundary in CentralArizona Clay 1'1. (;onway Karl Karlscrom Leon T. Silver u.�. (;eological Survey Norcnern Ar�zonaE. Un�v ers�cy l:alirorma ln scuuce of Technology Flag s"arr . Ar�zona Flag sCa!! . Ari zona Pasadena . l:aliiorn�a �bUUl �bOll �ll�� Ches"er T. Wruc l INTRODUCTION tion. and "southern" province rocks are fundamentally continental to possibly passive continental margin One of the firs t major di scoveri es of the infant rocks . including rhyoli te caldera suites and mature discipline of zircon geochronology was that the Early sandstones . The correspondence is not so good between Proterozoic of Arizona comprised two" age provinces structure and lithology. nor between structure and with a boundary in the central part of the state geochronology . "Northern" province rocks commonly (Silve r. Rocks in the central to have a ductile fabric and show evidence in several northwester19n65 part. 1967 of. the196 9).state are about to 1.78 places of polyphase de formation , whereas "southern" Ga . whereas those in the central to southeastern1.70 part province rocks generally are br ittlely deformed in one of the scate are about to Ga. Since these stage at high crustal levels . These ge neralizations . results were first repo 1.rte61d . the1. 71exact po sition and however. do not hold up everywhe re . nature of the two-province boundary have been the The Early Proterozoic terrane contains a number subject of much debate and still elude geologists. It of major north- and northeast-trending faults or shear has become obvious that several iterations of field zones . along which the movement directions are not y' : and geochronologic studies . each giving di rection and lully oec�pnered; m�n�mum ai splacements �n some case " raising quest ions for the next. are required for a are on "ne oroer of "ens of kilomet ers . Tne s�gni r- understanding of the bounda ry and the Early Proterozoic history of Arizona in any detail. Because the two-province boundary in Arizona extend north eastward into the mid-continent and perhapsmay farther and because the Trans ition Zone in Arizona offers superb out crops across this boundary . Arizona may hold answers to ques tions regarding the Early Proterozoic crustal growth of the southern part of the North Ame rican craton. One of the major goals of this field trip is to examine the nature of the proposed boundary through stops and discussions of rocks in both provinces. The controversy surrounding the nature of the boundary and the two provinces extends to the authors of this field guide . We cannot find agreement on definitions. It appears that the concept of a two province boundary. at le as t on a local scale . is in question. Recent ly. the boundary has been Viewed not as a simple line (e.g. a suture or shear zone). but as an area distributed over a distance of about km NW-SE in the trans ition zone (Conway and Karls150trom. Karlstrom and Conway . In other words . the1986 nort ; hern of the boundary1986). zone contains scattered examplespan of southern province rocks and the southe rn part of the boundary zone contains scattered areas of older rocks of the northern province. As ide from isotopic age. two sets of criteria may be used to assign rocks to one province or the other -- broad li thologic charact erization and deformational style. A fairly good correspondence exists between lithology and geochronology: "northern" province rocks are fundamentally submarine volcanic and volcani clastic rocks and penecontemporaneous batholi ths . most Figure Index and highway map of region of field likely of oceanic or continental-margin arc deriva- trip. 1.Sites to be visi ted are ci rcled numberS. (1-10) 48 Excerptsfro m "Tectonic and magmatic contrasts across a two-province Proterozoic boundary incentral Arizo na," by C. M. Conway, K. E. Karlstrom, 1..T. Silver, and C. T. Wrucke. Reprinted with permission from Davis, G.H., andVan denDolder, E.M., eds., Geologic diversity of Arizona and its margins; excursions to choice areas: Arizona Bureau of Geologyand Min eral Technology Special Paper 5, p. 158, 159, 160, 169, and 170 crustal origin and tectonic evolution. Other authors 9:00 - Site 6 A number of geologic units are found (Silver, Conway ) hold a view that the "southern" Gisela in a small area at Gisela: diorite of province rocks are basically a coherent continental (lunch) the Gibson Creek batholith, pendants suite that has for its substrate cratonized "northern" within the diori te , Payson Granite , province rocks , and that the faults separate blocks of Green Valley Hi lls Granophyre , rhyo similar crustal history. It may be that the ultimate lite of the Red Rock Group, and a res o lution of the problems lies in middle ground . hybridized mafite porphyry . The This paper concentrates on the Early Proterozoic mafite porphyry intrudes rhyo lite of of �entral Arizona. We realize that accumulating da ta the Red Rock Group and is intruded by to the northwest and southeast add complexities to our the Payson Granite. These are key interpretations , but they are beyond the scope of this relations that led to the hypothesis discussion. We agree that one boundary in central that a numbe r of felsic volcanic and Arizona is important ye t not fully unde rstood -- the hypabyssal units in the region are Mo ore Gulch fault . In any further discussion of a cogenetic pa rts of caldera boundary , unless speci fical ly stated otherwise, we are complexes . Pendants of stratified referring only to the Moore Gulch faul t. rock are the olde st known rocks in the Tonto Basin-Mazatzal Mountains TIMETABLE AND SITE DESCRIPTIONS region. The Agate Mountain thrust fault , probably of the same The route of the field trip and locations of generation as the thrust faults in si.es to be visited are shown in Figure 1. Sites are the Maza tzal Mountains , is also shown in other figures . In reading the site exposed at Gisela . a1..')des cri ptions , one should refer to Figures 2 and and 12:15 - Site 7 Layering (igneous lamina tion) in subsequent text for geologic context of the units3 Snows torm Mtn. gabbro-diorite of the Gibson Creek discussed. (optional stop) ba tholith. Characterized by plagioclase- and amp hibole-rich SITE DESCRIPTIONS AND OBJECTIVES laye rs, these layered rocks contras t TL'IE Wi th the layered gabbro of Round Friday, Oc t. 1987 Valley in having randomly oriented , 7:00 a.m. 23, Leave Phoenix. highly acicular amphibole . 9:00 - Site 1 Superb exposures of rhyolite ash-flow 1:00 - Site 8 Graywacke of the Eas t Verde River �ount Peeley tuff of the Red Rock Group lie on the North Peak Formation and a plug of granophyre southeas t face of Mount Peeley. At are overlain in this area by the this site, hike several hundred Deadman Quartzite of the Mazatzal meters up the slope through one or Group . Recent ma pping sugges ts that more probable cooling units. Rhyo a fold in the gr aywacke and several l ite in this exposure is typical of units in the Eas t Verde River Forma ash flows that are abundant in the tion are ove rlain in angular uncon upper pa rt of the ca. 1700 Ma Tonto formity by the Deadman Quartzite. Basin Supergroup . The granophyre that intrudes the - Site Examine li thic sandstone and shale of graywacke bears both granophyric and Slate11:30 Creek 2 the Alder Group and highly deformed spherulitic textures and is thus ( lunch) rocks of the Slate Creek shear zone . similar to a sill of the Green Valley (optional geologic stop) Hills Granophyre at King Ridge in 1:00 - Site Mazatzal Group stratigraphy and Tonto Basin. Barnhardt 3 deformational style . Descend through This area is important and Canyon the Mazatzal Group sect ion - Mazatzal controversial . One question is Peak Quartzite, Maverick Shale, and whether the graywacke and granophyre De adman Quartzite - towards the core are perhaps similar in age and we re of an ant icline . The Mave rick con deformed together prior to eros ion tains abundant me soscopic evidence and deposition of the Deadman for northwes t-verging thrusts and QuartZite, or whether the graywacke , folds. if it is older than the Gibson Creek 5:00 - Site 4 Examine layered gabbro in the Gibson batholith, was folded and then Round Valley Creek batholith. Several square intruded by high-level granophyre (optional stop) kilometers in this locali ty are that is es sentially the same age as underlain by two-pyroxene gabbro with the Deadman Quartzite. cumulate texture and compositional 4:30 Drive to Cottonwood. layering. gradation southeastward 6:00 Dinner, Camp Verde or Co ttonwood . appears to Aexi st from this ortho 7:30 Slides, maps, discussion - Best pyroxene-rich gabbro into hornblende- Weatern Cottonwood Inn, Cottonwood. rich gabbro and then into diorite. Sunday, Oct. 25 t:30 Dinner at Payson. 8:00 Leave Cottonwood. :30 Slides, maps, discussion - Swiss 9:00 - Site 9 Northern terminus of the Crazy Basin i Village Lodge , Payson. Crazy Basin Quartz Monzonite. Examine stratified rocks of the Yavapai Series and intrusive rocks of the Crazy Bas in Qua rtz Monzonite, and cons ider the timing of various phases of defor mation relative to metamorphism and plutonism. A new U-Pb zircon age of 1699 5 Ma for the Crazy Basin ± 49 Excerptsfrom "Tectonic and magmatic contrasts across a two-province Proterozoic boundary in central Arizona,� by C. M. Conway, K. E. Karlstrom,L T. Silver, and C. T. Wrucke. Reprinted with permission from Davis, G.H., andVan denDo/der, EM., eds., Geologic diversity of Arizona andits margins; excursions to choice areas: Ariz ona Bureau of Geology and Mineral Technology Sp ecial Paper 5, p. 158, 159, 160, 169, and 170 Quartz Monzonite indicates that this or continental-margin calc-alkaline arc affinity batho li th was crys tallizing at about (Anderson, 1978, 1986; Condie, 1986; Vance , 1986). the same time that rhyolites and These volcanic rocks and associated penecontem quartz arenites were being deposited poraneous batholiths are broadly similar to those of in the terrane south of the Moore late Phanerozoic circum-Pacific magmatic arcs. Gulch fault. Quartzite in northern Chino Valley (W ilson, 1939'· Si te 9A Margin of the Crazy Basin Quartz Krieger , Trevena , !�79 ) is an anomalous lithol- Monzonite. Examine cross-cutting ogy in tne!�b5 terrane; northwest of the Moore fault relationships of numerous dikes of and probably belongs to the Mazatzal Group,GulCh a major granite, aplite, pegmatite, and unit in the generally 1700 Ma terrane southeast of the tourmaline-bearing quartz veins in Moore Gulch fault. The Texas Gulch Formation, which pelitic rocks of the Yavapai res ts unconformably on strata of the Yavapai Series Series. The va riation in relative and on the Brady Butte Granodiorite, has lithologic age and degree of deformation similarity to the Alder Group of the southeastern suggests that these various materials terrane, but may older. were injected during deformation. Plutons northwestbe of the Moore Gulch fault that Site 9B Middleton Creek. Examine metamorphic are 1700 Ma are of special interest because they were rocks at the margin of the batho apparently emplaced at the same time that rhyolite lith. Staurolite-andalusite-garnet volcanism and quartz-areni te sedimentation were biotite assemblages in pelitic rocks occurring south of the Moore Gulch fault. These are record PiT condi tions of 3.7 kb and the Crazy Basin Quartz Monzonite (Site 9) in the 0 500 C. southern Bradshaw Mountains (about 1680 Ma, Blacet and Si te 9C Aplite dike north of the Crazy Basin others , 1971; 1699 5 Ma , Ka rlstrom and others, 1987) , and a grani te mass in the Arrastra Mountains contact . An aplite dike (1700 Ma ) ± intrudes Yavapai Series rocks just southwest of Bagdad, previously included in the Si�nal north of the Crazy Basin contact Granite (Lucchitta and Suneson , 1982 ; Bryant and along the Desoto Road . This dike Wooden, 1986). This class of granites is di stinct crosscuts an isoclinal fold in the from the older calcic to calc-alkaline batholiths tha: Yavapai Series and is itself bou are probably genetical ly related to volcanic belts of dinaged and foliated, further similar or slightly older age. ev�dence for syntecton�c (spec�I Southeas t of the Moore Gulch fault in Arizona, most U-Pb zircon ages range from 1610 to 1710 Ma �ca.l.ly syn-l';l ) �ntrusion of tne Datnolitn . (Conway and Silve r, 1987). In the Tonto Basin Site 9D Cleator shear zone . The east side of Mazatzal Mountains region, numerous ages on rhyolite the Crazy Basin Quartz Monzoni te is to rhyodaci te flows in the Tonto Bas in Supergroup are bordered by the Shylock fault zone , a 1700 to 1710 Ma (Silver , 1967; Silver and others, zone 1 to 3 km wide of vertical 1986) . Flows of this age are also found in the foliation and ve rtical stretching Redmond Formation of the Hess Canyon Group along the lineation. The vertical foliation Salt River (Livingston, 1969a , 1969b ; L. T. Silver, and folds in the Shylock are ove r unpublished data) and in the Pinal Schist in south printed in a wide zone by the Cleator eas tern Arizona (Silver, 1978). Widespread felsic shear zone and related asymmetrical hypabyssal units of the Diamond Rim Intrusive Suite in folds, which exhibit evidence for the Tonto Bas in are 1692 to 1703 Ma (Silver and sinistral strike-slip displacement . others , 1986), and felsic intrusive bodies in the 12:00 - Site 10 Hoore Gulch fault. Ductilely loutheas tem of the state are of similar age Moore Gulch deformed rocks of the Yavapai Series (Silver, 1978).part There is an apparent gap between crop out northwest of the fault, about 1692 and 1640 Ma . Granitic bodies ranging in whereas rocks to the southeast age from 1610 to 1640 Ma occur at the town of Young in �nclude br�ttle.ly Deformed equiv the northern Sierra Anchas (Conway , 1976), at alents ot tne Tonto Bas�n Super Sunflower in the central Mazatzal Mountains (Silver, group . The fault in this locality 1965), and at scattered lo calities in loutheastern has Tertiary movement , but the Arizona (Silver, 1978, unpublished data) . juxtaposition of diverse rock The Gibson Creek batholith and pendants of packages across the fault suggests stratified rockl at Giaela appear to be lithologica::y major Precsmbrian movement. anomaloul geologic un its in the southeastern terrane and are aome 40 million yesrs older tban most other OVERVIEW OF EARLY PROTEROZOIC GEOLOGY dated rocks southeast of the Moore Gulch fault . This batholith contraata petrologically with the spatially GEOCHRONOLOGY OF ARIZONA AND aaaociated 1700 rocka and is similar to the batho The major stratigraphic and plutonic groups and liths of the northeasternKa terrane . The dominant sub structural features of the Early Proterozoic of aqueous mafic volcanic rocks and turbidite graywa cke of the East Verde River Formation are lithologically central Arizona are shown in Figure 2. From the Moore more like the strata of the Yavapai Series than the Gulch fault to northwestern Arizona, U-Pb zircon ages Tonto Basin Supergroup , and these units may also range from about 1700 to 1775 Ma . The Yavapai Series predate the Gibson Creek batholi th. of Anderson and others (1971) and most plutonic rocks in the Bradshaw Mountains and Black Hills are about The large fellic complexes of the Tonto Basin in- 1720 to 1775 Ma (Anderson and others , 1971; L. T. Mazatzal Mountains-New River Mountains region, Silver' unpublished da ta; S. A. Bowring , 1987 , oral l comm. ) . Volumetrically less significant plutonic masses are about 1700 Ma , and a belt of volcanic rocks in the Bagdad area has volcanic rocks as young as 1709 Ma (Bryant and Wooden, 1986). 50 Excerpts from "Tectonic and magmatic contrasts across a two-province Proterozoic boundaryin central Arizona,�by C. M. Conway, 1(. E. Karlstrom, L T. Silver, and C. T. Wrucke. Reprinted with permission from Davis, G.H., and Van denDolder, E.M., eds., Geologic diversity of Arizona and its margins; excursions to choice areas: Arizona Bureau of Geology and Mineral Technology Sp ecial Paper 5, p. 158, 159, 160, 169, and 170 area but become tighter to the southeast, where F2 folds are highly attenuated and exhibit curved hinge lines believed to be related to hinge line rotation affected al l of the Tonto Basin-Mazatzal Mountains during progressive shortening. The northeas t-trending area (Conway , 1976) , but it is still unclear whetner vertical foliation that has an axial-plane orientation it �y have also undergone earlier (pre-Tonto Basin to the tight folds fo rms the dominant fabric of the Suprgroup ) penetrative de formation, as did the Yavapai Series ; it is interpreted to be a composite Ya'. ,1'ai Series and associated batholi ths to the fabric cons is ting of transposed bedding , S com no::�west. Similar questions regarding deformational l pOSitional layering, and S 2 cleavage . It can be ana metamorphic history ap ply to the East Verde River Formation. The relationships at the northern end of traced eastward to the area of the Crazy Basin Quartz Monzonite (1699 Ma ) and to the Shylock fault zone. the Mazatzal Mountains (Site 8) are thus of key importance because in this area folded graywackes of DEFORMATION the East Verde River Formation are unconformably OF EMPLACEMENTBASIN AND QUARTZ MONZONITE overlain by flat-lying Mazatzal Group rocks (Wrucke THE CRAZY aDd Conway , in prep.) In the Crazy Basin area (Figure 11), the Sl/s2 YAVAPAI SERIES ASSOCIATED BATHOL ITHS foliation is bent around the north terminus of the AND Crazy Basin Quartz Mo nzonite. This warping of Rocks northwest of the Moore Gulch fault include foliation was interpreted by DeW itt (1979), O'Hara tr.� Yavapai Series of Anderson and ot hers (1971) and (1980) , and Blacet (1985) to be related to post vc�:-"'Ii nous batholithic rocks . Strata of the Yavapai tectonic intrusion of the batholith, but recent work Series are crosscut by batholiths that are pre by Argenbright and Ka rlstrom (1986) suggests that the dominantly granodioritic and are probably temporally pluton was syntecton ic, in agreement with the early interpretations of Jagger and Palache (1905). A and gene tical ly rela ted to the vo lcanic rocks . Figures 10 and 11 show lithologic subdivisions macroscopic anticline cored by volcanic rocks jus t north of the Crazy Basin Quartz Monzonite (Figure 11) , rather than the stratigraphic subdivisions of Anderson believed to be an F fold because of overprinting of and others (1971) because structural complexi ty makes 2 stratigraphic subdivisions highly cont rovers ia l. earlier generation folds on its limbs , is crosscut by Rocks in this region are geographically divided into a dike of ap lite that is the same age (1700 Ma) and of three major areas by fault zones , the north-trending similar lithology (muscovite-bearing) as the batho Shylock fault and the northeast-trending Chaparral lith. By this evidence , folding (F and F2) was in 1 fault . Ande rson and coworkers proposed a statigraphy part pre-1700 Ma . The ap lite, however, is folded and roughly corresponded to this geographic contains a cleavage that has an axial-plane orienta s�"dth'-tiv ision. Their Ash Creek Group (oldes t) is tion to the large fold (Site 9C) , indicating that the reJcricted to the area east of the Shylock faul t, the fold was tightened af ter inject ion of the ap lite at Big Bug Group lies �inly between the Shylock and 1700 Ma. Independent evidence that the Crazy Basin Chaparral faults, and the Green Gulch Volcanics of the Quartz Monzonite crys tallized during F2 shortening Big Bug Group lies northwes t of the Chaparral fault . comes from the eastern margin of the batholith. Here, The Texas Gulch Formation in the central block res ts stretching lineations in highly evo lved phases of the with unconformity on the 1750 Ma Brady Butte Grano granite are defined by aligned and boudinaged tourma diorite and on Big Bug Group volcanic rocks . This line needles. These lineations are steeply plunging , unit was cons idered by Anderson and others to be subparallel to the vertical L2 stretching lineation in youn ger and not part of the Yavapai Series , although the Shylock fault zone . new structural interpretations suggest these slates F folds and S2 layering are refolded by F3 folds 2 and graywackes may correlate with graywackes and in a wIde zone close to the Shylock fault zone . F3 pelitic schists in the Big Bug Group around the Crazy folds have a consistent (sinistral ) asymme try. These a�sin Quartz Monzoni te. If so, the unconfOrmi ty at folds and their northeas t-trending aXial-plane t:� base of the Texas Gulch Formation [and possibly at cleavage are believed to be the product of sinistral the base of pe li tic rocks in the Crazy Basin area strike-slip displacement over a wide zone , but concen (Site 9)] may represent a regional change from trated near the Cleator shear zone . The Cleator shear 2 volcanism and plutOnism in the arc to es tabli shment of zone (Figure 1 ; Darrach and others , 1986) is a forearc or backarc sedimentary basins in the Yavapai seve ral-hundred-meter-wide mylonite zone with subhori Series . zontal stretching lineation and abundant sinistral Early deformation apparently predated 1740 Ma, in kinematic indicators . It ove rprints F2 folds (Figure 2 the Ash Creek Group , and perhaps the in Big Bug 1 ) but apparently moved while the Crazy Basin Quartz Group. It was this deformation that may have been Monzonite waa still partially liquid , as shown by contemporaneous with collision of island-arc terranes sinistral vein arrays filled with granite in the eas t and incipient development of continental crust. This margin of the batho li th. Sinistral kinematic indica early deformation, however, was followed by later tora are alao present in the west and north margins of deformation in the Big Bug Group, and it is this later the batholi th, indicating that the entire batholith •• deformation that is 1IIOSt pertinent to the discu.sion w involved 1n a wide zone of distributed sinistral as a cf the significance of the Moore Gulch fault shear. Shal lowly plunging stretching lineations de tectonic boundary between diverse provinces. fined by tourmaline on che north and we st of the The earlies t deformation in the Big Bug Group is batholith apparently reflect the strike-slip movement , aeen in the Brady Butte area. ' recumbent iaoclinal just as similar lineations on the east margin reflect 1 folda in this area fo ld the pretectonic Brady Butte the dominance of vertical stretching during Granodiorite (1750 Ma) and the unconformably overlying shortening. e us Gulch Fo rmation. The unconformity between these The data suggest that F2 shortening and F3 two units is marked by boulders of granodiorite in sinistral strike slip were both contemporaneous wi th basal conglomera te and is a mappable form surface that crystallization of the batho li th at about 1700 Ma. defines the recumbent folds (Karlstrom and Conway, These data are compatible wi th an overall trans- 51 Excerpts from 7e ctonic and magmaticcontrasts across a two-province Proterozoic boundaryin centralArizona," by C. M. Conway, K. E. Karlstrom, L T. Silver, and C. T. Wrucke . Reprinted with permission from Davis, G.H., andVan denDolder, E.M., eds., Geologic diversity of Arizona andits margins,' excursions to choice areas: Arizona Bureau of Geology andMin eral Te chnologySp ecial Paper 5, p. 158, 159, 160, 169, and 170 EXPLANATION / APl.ITE / / (1700 1010) o CRAZY BASIN QUARTZ MONZONITE (1699�5Mo) EJ BADGER SPRING GRANODIORITE (1743.101010) YAVAPAI SERIES o GRAYWACKE AND PELITIC SCHIST EZJ MAFIC METAVOLCANIC ROCKS . CHERT . FE-FM. FELSIC' MAFIC METAVOLCANIC ROCKS FOLIATION " STRETCHING LINEATION ./ MOVEMENT ZONE Figure 11. General ized geologic map of the Crazy Basin Quartz Monzonite, showing locations of stops in Site 9 and area of detailed map of Cleator shear zone (Figure 12) . o pres s10nal shortening across the Shylock fault zone , the margin was at about SOO C and 3.7 kb, as shown by with shortening and strike slip being partitioned into garnet-biotite geothermometry and garnet zoning pro Separate component s, as is common during transpression file (M. Williams , 1987, oral comm. ). Porphyroblasts (Sanderson and Marchini , 1984). overgrow 5 /5 foliation and are themselves folded , 1 2 Well-developed foliation in the Crazy Basin boudinaged, and rotated, indicating syntectonic growth Quartz Monzonite (Figure 11) also rules out the during 5 /5 , Thus , plutonism, deformation, and 2 3 interpretation that the batho lith i8 pos ttectonic , metamorpnism are all believed to have been broadly especially because the internal foliation crosscuts synchronous (1699 Ma) and to have taken place at the margins of the grani te and can be shown to be depths of to 15 This is compatible with the continuous with the regional foliation. Foliation in strongly peraluminous12 km. che mistry of the Crazy Basin the granite is domainally developed, as in many Qua rtz Monzonite, which suggests crystallization deformed grani tes (Page and Bell, 1986) and is defined dep ths of greater than 2.5 kb (Miller, 1985). shape-preferred orientation of feldspar , quartz , by phyllos ilicate grains . The foliation is northeast andtren ding and is closer in orientation to 5 than 5 3 . , (Figure 11). 52 Excerpts from "Geology and structural relations in the southernNew River Mountains and the significance of the Moore Gulch shear zone," by Ed DeWitt Geology and structural relations in the southern New River Mountains and the significance of the Moore Gulch shear zone Ed DeWitt M.S. 905, U. S. Geological Survey, Denver, CO 80225 OBSERVATIONS lithologically identical to hematitic sedimentary rocks in In the central and northern New River the south-central partof the New River Mountains (unit Mountains (fig. 3 of volwne and geologic map on Xps, map on following page). In agreement with fo llowing page), the thisMoore Gulch shear zone (Maynard, Anderson (1989), I interpret the Moore Gulch shear zone 1986) juxuposes relatively unmetamorphosed and to die out to thesouth into regionally fo liated Early undefonned 1.7.oa rhyolite on the east (unit Xrby) with Proterozoic rocks. 1.7O-Ga rhyolite of the central New fo liated, older (pre-1.72 Ga) metavolcanic rocks (units RiverMountains appears to have been deposited on top Xvs, Xch) on the west. the central and eastern of the suite of mixed metavolcanic and metasedimenury New Xb,River Mountains, the 1.7-GaIn rhyolite displays rocks (units Xvs and Xsv) that are intruded by the quartz spectacular welded tuff textures, and intruded on the diorite of Bland. east by its subvolcanic-equivalent granophyreis (DeWitt, Near Brooklyn Peak, in the northern New River 1987; unpub. mapping, 1990). Throughout the central Mountains, the granophyre thatintrudes its cogenetic, and eastern New River Mountains the rhyolite and 1.7-Ga rhyolite in the central part of the range cuts granophyre lack the distinctive northeast-striking across the trace of the Moore Gulch shear zone (DeWitt, regional fabricof most Early Proterozoic rocks in central unpub. mapping, 1990) and intrudes metabasalt and Arizona. Pre-l.72-Ga metavolcanic strata westof the mixed metavolcaniclastic strata that similar in central part of the Moore Gulch shear zone fo liated composition to thoseexposed west ofare the shear zone in metabasalt, of metarhyolite, metachert,are iron the central part of the range. I interpret these relations to fo nnation. andthin marble, beds and mixed metavolcaniclastic indicate that displacement on the shear zone, in the rocks (Maynard, 1986; DeWitt, unpub. mapping, 1990). northern partof theNew River Mountains, had largely The metabasalt intruded by the pre-tectonic quartz ceased by thetime that the granophyre intruded the 1.7- diorite of Bland is(Jerome, 1956), which strongly rhyolite ash-flow deformed not only in proximity to the shearis zone, but Ga I interpret thetuff Moore Gulch shear zone to be west, all the way to Black Canyon City (Wino, 1982; one of a family of zones of variable high strain in the DeWitt, unpub. mapping, 1989). Bowring andothers Early Proterozoic terrane of ce:;tral Arizonato (Shylock (1986) determined a U-Pb zircon age of 1.72 Ga for the and Mountain Spring zones others) that quartz diorite, which indicates that the metavolcanic accommodated crustal shortearening during regional rocks on the west side of the shear zone pre- l.72 Ga. deformation at 1.7 Because the Moore Gulch she:lI' the southern New River Mountainsare (geologic zone dies out to theGa. south and intrudedby 1.7 -Ga(?) map on foInllowing pate), the Moore Gulch shear zone granophyre to the north, the feisature not appe:lI' to be anastomoses and dies out into regionally fo liated rocks. a crustal in scale as suggested by Karlstromdoes and Bowring Imporuntly, the 1.7 -Ga rhyolite of thecentral New River (1988) and Karlstrom and others (1990), Mountains becomes more and more fo liated to the west and south. Along the drainage of New River, the rhyolite passes from undeformed welded and fra gmental flows to rhyolite that a regionaltuff cleavage, to fo liated mewhyolite, and into hasstrongly fo liated quartz porphyty over a distance ofless one-halfmile. Mixed metasedimentary and metavolcanicthan strata (unit Xsv) interbedded with the 1.70-0a rhyolite along the drainageare ofNew River (geologic map on fo llowing page), indicating that the base(7) of the rhyolite gradational downward into rock types commonis west of the shear zone. South of the shown on the mapon the fo llowing page, but withinarea the of figure 3 of volwne, strongly foliated metarhyareaolite exposedthis in roadcuts along 1- 17 to the north of the is town of New River. There, the metarhyolite interfolded with distinctive hematitic siltstone andis wacke that is 53 Excerpts from "Geology and structural relations in the southernNew River Mountains and the significance of the Moore Gulch shear zone," by Ed DeWitt Geologicmap of theNew RiverMts. area EXPLANATION . � .. : .: .. :::.. � Tertiary -: ". " .." � .�\:::: :::: � volcaniclastic rocb : . ...:-. :.:. ' .. . . � .«. , : :: � .� Phyllite ad date Pmlt I;;f/rl I Rhyollie md ISh-flow tuff I Xdly --001.� trip .� Route of field . � 1mi ...... : . � ." .. ::. .. . o 1km : :-. . : .. .' . . Xb 54 Excerpts from "Gravity and magnetic evidence fo r an Early Proterozoic crustal boundary along the southern Shylock fa ult zone, ce ntral Arizona," by R. S. Leighty, D. M. Best, and K. E. Karlstrom. Gravity and magnetic evidence for an Early Proterozoic crustal boundary along the southern Shylock fault zone, central Arizona Robert S. Leighty David Best Depanment of Geology, Nonhem Arizolla Un iversity, Flagstaff, Arizona Karl E.M. Karlstrom 8601 1·6030 ABSTRACT Ash Creek blocks. The southern SFZ appears separate different crustal (or upper crustal) columns,to East-west trending complete Bouguer and whereas the northern SFZ does not. residual Bouguer gravityprofiles across the southern Sbylock fa ult zone (SFZ) show a prominent 20-30 INTRODUcnON mGal long-wavelength gradient. with lower gravity to the west. These data suggest that the crust to the The Early Proterozoic orogenic belt in Arizonais west is either thicker or less dense than the crust to segmented by north- and northeast-trending the east, or both. The residual Bouguer gravity deformation zones, which have an enigmatic tectonic gradient of the southern SFZ also parallel to a significance. These zones are tens of kilometers long, 400-500 gamma east-to-west increaseis in the residual several kilometers and appear to be crustal aeromagnetic field. The SFZ located near the discontinuities. Thesewide, deformation zones may be is middle of the gravity'and magnetic gradients, and we initial accretionary boundaries (i.e. sutures) interpret it as a maj or regional crustal boundary. (Karlstrom and Bowring, 1988), intraplate high strain Two-dimensional crustal models that use lateral zones during orogenic shortening (Bergh and density contrasts provide the best approximations of Karlstrom, pers. comm.), and/or zones that the observed long-wavelength gravity anomaly. accommodated differential uplift long after orogenic Reasonable agreement the calculated and activity (Bowring and Karlstrom, 1990). observed anomalies is producbetweened by using a slight The purpose of this paper is to examine the (0.02-0.03 Mg/m·J) east-to-west decrease in average gravity signature of one of these zones in central density integrated over the entire crust. or by Arizona, the Shylock fault zone (Anderson and incorporating lower density (e.g., granitic) material, Creasey, 1958). This 6O-km-Iong, 2-km-wide zone is with a density contrast of Mgfm-3, into the characterized by sub-verticalfoli ation, steeply-plunging upper 10-15 of the western-0_06 block. A plausible but lineation, andtranspositio n of rock units. The Shylock less likely modelkm uses a smaIl « 4 km) step to fault zone (SFZ) is overlapped at its north end by thicken the crust in the western block, with no lateral undeformed Cambrian Tapeats sandstone, indicating cbanges in density. The magnitude and wavelength a Precambrian movement history. of the gradient are not readily modelled in terms of New gravity data were collected along and across individual granitoids exposed at the surface, such as the zone and were added to existing data. This study the Crazy Basin Quartz Monzonite. will attempt to: (1) describe the complete and The distinct gravity and magnetic signatures of residual Bouguer anomaly maps, as well as tbe the southern SFZ contrastwith those of the northern residual aeromagnetic anomaly map of the Bradshaw SFZ. None of the crustal models sausfactorily Mountain region, an area of twelve 7.5 minute matches the relatively flat residual Bouguer gravity quadrangles centered around Mayer (Fig. 1); (2) across the northern SFZ. A crustal model using delineaterelationships between short-wavelength( < 50 little, if any, density and thickness contrasts fits this km) anomalies and the surface distribution of profile more adequately. The north-south trending Proterozoic andPhanerozoic rocks; and(3) model the residual magnetic anomaly also disappears across longer-wavelength (>50 km) residual Bouguer the northern SFZ. The relatively subdued residual anomalies aaoss the SFZ in terms of different aeromagnetic field across the DOrthUU SFZ densities and/or thicknesses of austal blocks across indicates that the magnetic character of rocksarea on the fault zone. either side of the northern SFZis verysimilar. The boundary along the southern SFZ between Regional Geophysical Framework the western Big Bug block and the eastern Ash Creek block is of a different nature than that along the Regionalgravity maps of Arizona (Lysonski and northern SFZ, which separates the Green Gulch and others, 1980; Aiken and others, 1981) display a 55 Exce rpts from "Gravity and magnetic evidence fo r an Early Proterozoic crustal boundary along the southernShylock fault zone, ce ntral Arizona," by R. S. Leighty, D. M. Best, and K. E. Karistrom. � ii z r,:) :z N C> e ,.,. ;..... CO> ..., ....b II ...... E ;!; � Z � c::> � b c::> oS� = c - N CI C U �CQ >-. "0 .s;I) 1/ oS ... 0 1:10 � It) e ::.:: E 1 0= � 1/ 0 rc1:1 0 D:l = -;"0 � = ..,. � bN t ..,.... N � 56 Excerpts from "Gravity and magnetic evidence fo r an Early Proterozoic crustal boundaryalong the southernShylock fault zone, central Arizona," by R. S. Leighty, D. M. Best, and K. E. Karlstrom. of 2.67 Mg/m-3. In this survey, inner terrain corrections were calculated manually for all new stations due to the generally ruggednature of the field area, while outer terrain corrections (2.6 to 167 km) were computed using the digital elevation data base for Arizona. Corrections accounting for earth curvature were also applied. Using a digital topographic data base, the computer program RESID calculates the regional value of a gravity station and subtracts the variable thickness Bouguer slab effect fr om the free·air anomaly, resulting in residual Bouguer gravity values (Aiken and others, 1981). Both the short- and long-wavelength residual Bouguer anomalies were interpreted using a standard two-dimensional modeling program based on Talwani and others (1959). Geologic maps from several sources (Anderson and Creasey, 1958; Anderson and Blacet, 1972a, 1972b, 1972c; Blacet,1985) control the shallow crustal models. Modeling of the deeper crust is weakly contrained by the crustal velocity structure of several seismic studies (Warren, 1969; Hauser and others, 1987; Hauser and Lundy, 1989). Selection of specific densities for lithologic units used in two- dimensional computer modeling poses a problem due to variations in rock types, so averaged bulk density values were used (Table 1). Average densities for the crustal models may range from 2.70-2.76 Mg/m-3 for the upper and middle crust, to 2.90 Mg/m-3 and 3.30 Mg/m-3 the lower crust and upper mantle, respectively.for Because gravity modeling uses density contrasts, these average values can vary within reasonable limits. The aim in this survey is to describe possible lateral changes in the Al general density structure across the fault zone. W 700 DESCRIPTION OF THE GRA AND MAGNETIC FIELDS VITI •••••• A, .A,' 600 -0- B-B' ---- c-c' Complete Bouguer Anomaly Map -,- 0-0' �oo --E-E' '" c: The complete Bouguer anomaly map of the study � 400 � area (FIg. 4A) represents a combination of effects c: '" produced by both shallow and deep sources. Gravity values range from - 173 mGals to mGals. -126 . Although a large gradient (-20mGa ls over 15 km) 200 .!.-._.- dominates the southern portion of the area, tbe 100 8) gravity field to the north is more convoluted. A 112022' :30."" 112·00'00· ..., detailed description individual features on this map is not critical as of the residual Bouguer map, but descripastion of the torproflles across this map are useful. Note that the major gradient in the southwest part of the map trends northeast and does not obviously Figure 8. (A). Residual aeromagnetic correspond to the SFZ. anomaly map and profiles oC the study area Figure 4A shows the location of profUes AI-AI', (Crom Sauck and Sumner, 1970); contour B-B', C-C', and E-E'. Each profUe is km 0·0', 30 interval = gammas. (B) Profiles correspond long and is oriented east-west. The northernmost to those in2S Figures 4A and 4B. profUe, AI-A!', crosses the quartz diorite of Cherry 57 Excerpts fro m "Gravity and magnetic evidence fo r an Early Proterozoic crustal boundary along the southern Shylock faultzone, central Arizona; by R. S. Leighty, D. M. Best, and K. E. Karlstrom. ,.. , b md .. a: . 0 0 A) w a:- � w .!!! ::I I!) 0 �� ''' . -;;; ::I 0 ::I I!) I!) I!) ·20 E -20 ::I E --- CD -CMIA 0 - 4 CD >- 0 0->- ..l -40 � r- �- : ..Ir- �- --CM IB ::I> ::I> e � O� a: -60 -a: lil -60 w I!) �I!) """- C M IC a: a: .810 BUQ blotll ASh Crull block Malonol block 8iq Bu; bloc" AS" Crnll blOCIl MOIOllol block -80 0 '-CM IO -80Q D(H5IT1 CO HT'U$oTS DENSITl' COHHtUTS � '''. /M- )I ] , ..,/.oJ, J: e J: CN I A-O=O 0- Il. .. 3 = 0.01 Il. l' 0 ... 11 OR '.ml 1O OR ,Iun) 0 _0 ...... U eM .& 14 eM) , • - 'W'I " . eM,e I 'MID . to EfN'IO� 0' Db , .. d [t'lvt'loOt' 0' Obur"ed Gtavlt, PrQ,il.. Grov.,y Profiln __ .. .--r ___ __--r- a: 0 a: 0 w B) w D) ::I I!)- L? ::I 0 0.. ::1 -;;; -::::::;' ::I L? I!) -20 - 20 � o E C M 2 A E A CD -- CD -Chl 2B 0 ..1>- ..l >- -C1oI48 exr- -40 � !: -40 ::1- -Chl 2C ::I > 0> 0 ex -ex a: --Chi 20 VI w I!) -60 -80 8'0 BUQ bloca A", Ctu bloca "'0101101 bloca SiC) BuO bloc. Ash Crtfll bloca MoroUal blocll -800 0[N5IT1' CON'''AST5 ... Cw •• I 0.06-10,. l 10 ] 'M,I_- , ! C ·OO' ·I� •• IS J: :r '"Z'' ' 002 UUC . 0 04 0- .... Il. Il. C"ZI -OOl ,"lO 'O os W ... sa 0 Q ... .. OR =O OR =O 58 REFERENCES CITED Anderson, C. A., 1972, Precambrian rocks in the Bowring, Sam, Karlstrom, K.E., and Chamberlain, K., Cordes area, Yavapai County, Arizona: U.S. 1986, U-Ph zircon constraints on Proterozoic Geological Survey Bulletin 1345, 36 p. tectonic evolution in central Arizona [abs.]: Anderson, C.A., and Blacet, P.M., 1972a, Geologic Geological Society of America Abstracts with map of the Mount Union quadrangle, Yavapai Programs, v. 18, no. 5, p. 343. County, Arizona: U.S. Geological Survey Canney, F.C., Lehmbeck, W.L., and Williams, F.E., Geologic Quadrangle Map GQ-997, scale 1967, Mineral resources of the Pine Mountain 1:62,500. Primitive Area, Arizona: U.S. Geological Anderson, C.A., and Blacet, P.M., 1972b, Precambrian Survey Bulletin 1230- J, p. Jl-J45. geology of the northern Bradshaw Mountains, Conway, C.M., 1976, Petrology, structure, and Yavapai County, Arizona: U.S. Geological evolution of a Precambrian volcanic and Survey Bulletin 1336, 82 p. plutonic complex, Tonto Basin, Gila County, Anderson, C.A., and Blacet, P.M., 1972c, Geologic Arizona: Pasadena, California Institute of map of the Mayer quadrangle, Yavapai County, Technology, Ph.D. dissertation, 460 p. Arizona: U.S. Geological Survey Geologic Conway, C.M., Kar1strom, K.E., Silver, L.T., and Quadrangle Map GQ-996, scale 1:62,500. Wrucke, C.T., 1989, Tectonic and magmatic Anderson, C.A., and Creasey, S.C., 1958, Geology and contrasts across a two-province Proterozoic ore deposits of the Jerome area, Yavapai boundary in central Arizona, in Davis, G.H., County, Arizona: U.S. Geological Survey and VandenDolder, E.M., eds., Geologic Professional Paper 308, 185 p. diversity of Arizona and its margins; excursions Anderson, C. A., and Creasey, S.C., 1967, Geologic to choice areas: Arizona Bureau of Geology map of the Mingus Mountain quadrangle, and Mineral Technology Special Paper 5, p. Yavapai County, Arizona: U.S. Geological 158-175. Survey Map GQ-715, scale 1:62,500. Darrach, M.E., 1988, A kinematic and geometric Anderson, C.A., and Nash, J.T., 1972, Geology of the structural analysis of an Early Proterozoic massive sulfide deposits at Jerome, Arizona--A crustal-scale shear zone; the evolution of the reinterpretation: Economic Geology, v. 67, p. Shylock fault zone, central Arizona: Flagstaff, 845-863. Northern Arizona University M.S. thesis, 81 p. Anderson, Phillip, 1987, The Proterozoic tectonic DeWitt, Ed, 1976, Precambrian geology and ore evolution of Arizona: Tucson, University of deposits of the Mayer-Crown King area, Arizona, Ph.D. dissertation, 416 p. Yavapai County, Arizona: Tucson, University Anderson, Phillip, 1989, Stratigraphic framework, of Arizona, M.S. thesis, 150 p. volcanic-plutonic evolution, and vertical DeWitt, Ed, 1979, New data concerning Proterozoic deformation of the Proterozoic volcanic belts of volcanic stratigraphy and structure in central central Arizona, in Jenney, J.P., and Reynolds, Arizona and its importance in massive sulfide S.J., eds, Geologic evolution of Arizona: exploration: Economic Geology, v. 74, p. 1371- Arizona Geological Society Digest 17, p. 57- 1382. 148. De Witt, Ed, 1983, Precious metal content of Anderson, Phillip, and Wirth, K.R., 1981, Uraniwn Proterozoic massive sulfide deposits in Arizona potential in Precambrian conglomerates of the [abs.]: Geological Society of America, central Arizona arch: U.S. Department of Abstracts with Programs, v. 15, p. 298. Energy Open-File ReportGJBX-33(81), 122 p. De Witt, Ed, ed., 1987, Proterozoic ore deposits of the Argenbright, D.N., 1986, Geology and structure of southwestern U.S.: Society of Economic Proterozoic rocks of the Yavapai Supergroup in Geologists Guidebook Series, v. 1, 189 p. Crazy Basin, central Arizona: Raleigh, North DeWitt, Ed, 1989, Geochemistry and tectonic polarity Carolina State University M.S. thesis, 81 p. of Early Proterozoic (1700-1750 Ma) plutonic Blacet, P.M., 1966, Unconformity between gneissic rocks, north-central Arizona, in Jenney, J.P., granodiorite and overlying Yavapai Series and Reynolds, SJ., eds, Geologic evolution of (older Precambrian), central Arizona: U.S. Arizona: Arizona Geological Society Digest Geological Survey Professional Paper 550-B, p. 17, p. 149-164. 1-5. De Witt, Ed, and Waegli, Jerome, 1986, Gold in the Blacet, P.M., 1985, Proterozoic geology of the Brady United Verde massive sulfide deposit, Jerome, Butte area, Yavapai County, Arizona: U.S. Arizona: U.S. Geological Survey Open-File Geological Survey Bulletin 1548, 55 p. Report 86-0585, 41 p. 59 Elsing, M.J., and Heineman, R.E.S., 1936, Arizona Survey Professional Paper 467, 127 p. Metal Production: Arizona Bureau of Mines Lindberg, P.A., 1986, An overview of Precambrian ore Bulletin 140, 112 p. deposits of southwestern United States, in Gastil, R.G., 1958, Older Precambrian rocks of the Beatty, Barbara, and Wilkinson, P.A.K., eds., Diamond Butte quadrangle, Gila County, Frontiers in geology and ore deposits of Arizona Arizona: Geological Society of America and the Southwest: Arizona Geological Society Bulletin, v. 69, p. 1495-1514. Digest 16, p. 343-349. Gomez, Ernest, 1979, Geology of the south-central part Lindgren, Waldemar, 1926, Ore deposits of the Jerome of the New River Mesa quadrangle, Maricopa and Bndsbaw Mountains quadrangles, Arizona: County, Arizona: Aagstaff, Northern Arizona U.S. Geological Survey Bulletin 782, 192 p. University, M.S. thesis, 80 p. Ludwig, K.R., 1973, Precambrian geology of the Hurlbut, D.F., 1986, The geology and mineralization at central Mazatzal Mountains, Arizona (part I) the Boggs mine, Yavapai County, Arizona, in and lead isotope heterogeneity of Precambrian Beatty, Barbara, and Wilkinson, P.A.K., eds., igneous feldspars (part IT): Pasadena, California Frontiers in geology and ore deposits of Arizona Institute of Technology, Ph.D. dissertation, 363 and the Southwest: Arizona Geological Society p. Digest 16, p. 374-376. Maynard, Steve, 1986, Precambrian geology and Jaggar, T.A., and Palache, Charles, 1905, Description mineralization of the southwestern part of the of Bradshaw Mountains quadrangle, Arizona: New River Mountains, Maricopa and Yavapai U.S. Geological Survey Atlas Folio 126, 11 p. Counties, Arizona: Albuquerque, University of Jagiello, K.J., 1987, Structural evolution ofthe New Mexico, M.S. thesis, 155 p. Phoenix Basin, Arizona: Tempe, Arizona State McKee, E.H., and Anderson, C.A., 1972, Age and University, M.S. thesis, 156 p. chemistry of Tertiary volcanic rocks in north Jerome, S.E., 1956, Reconnaiss.ance geologic study of central Arizona and relationships of the rocks to the Black Canyon schist belt, Bradshaw the Colorado Plateau: Geological Society of Mountains, Yavapai and Maricopa Counties, America Bulletin, v. 82, p. 2767-2782. Arizona: Salt Lake City, University of Utah, McKee, E.H., and Elston, D.P., 1980, Reversal Ph.D. dissertation, 115 p. chronology from a 7.9 to 11.5 M.Y.-old Johnson, M.G., 1972, Placer gold deposits of Arizona: volcanic sequence in Arizona; comparison with U.S. Geological Survey Bulletin 1355, 103 p. ocean floor polarity record: Journal of Karlstrom, K.E., 1989, Early recwnbent folding during Geophysical Research, v. 85, p. 327-337. Proterozoic orogeny in central Arizona, in O'Hara, P.F., 1987, Early Proterozoic gold Grambling, J.A., and Tewskbury, B.J., eds, mineralization, alteration assemblages, and 1989, Proterozoic geology of the southern geochemistry of the Huron-Montezuma Rocky Mountains: Geological Society of prospect, Yavapai County, Arizona, in DeWitt, America Special Paper 235, p. 155-171. Ed. ed., Proterozoic ore deposits of the Karlstrom, K.E., and Conway, C.M., 1986, southwestern U.S.: Society of Economic Deformational styles and contrasting Geologists Guidebook Series, v. 1, p. 161-166. lithostratigraphic sequences within an Early O'Hara, P.F., Yoder, M.P., Stamm, C.A., Niver, Proterozoic orogenic belt, central Arizona, iD. Randall, and Maliga, Jody, 1978, The Nations, J.D., Conway, C.M., and Swann, G.A., Precambrian Texas Gulch Formation boundary eds., Geology of central and northern Arizona: fault system, Yavapai County, Arizona--A Geological Society of America, Rocky folded unconformity'? [abs.]: Geological Society Mountain Section, Field Trip Guidebook, p. 1- of America Abstracts with Programs, v. 10, no. 26. 3, p. 140. Karlstrom, K.E., and O'Hara, P.F., 1984, Polyphase Reynolds, SJ., Aorence, F.P., Currier, B.A., Anderson, folding in Proterozoic rocks of central Arizona A.V., Trapp, R.A., and Keith. S.B., 1985, [abs.]: Geological Society of America Compilation of K -Ar age determinations in Abstracts with Programs, v. 16, no. 4, p. 226. Arizona: Arizona Bureau of Geology and Keith, S.B., Gest, Donald, DeWitt, Ed. Woode-Toll, Mineral Technology Open-File Report 85-8, Netta, and Everson, B.A., 1984, Metallic 320p. mineral districts and production in Arizona: Sturdevant, J.A., 1975, Relationship between Arizona Bureau of Geology and Mineral fracturing, hydrothermal alteration, and Technology Bulletin 194,58 p., 1 sheet, scale distribution of copper, Big Bug area, Yavapai 1:1,000,000. County, Arizona: University Park, The Krieger, M.H., 1965, Geology of the Prescott and Pennsylvania State University, Ph.D. Paulden quadrangles, Arizona: U.S. Geological dissertation, 280 p. 60 Swan. M.M., 1987, Geology and gold mineralization at the Early Proterozoic Bell Ranch prospect, Yavapai County, Arizona, in DeWitt, Ed, ed., Proterozoic ore deposits of the southwestern U.S.: Society of Economic Geologists Guidebook Series, v. 1, p. 169-173. Swan. M.M., Hausen, D.M., and Newell, R.A., 1981, Lithological, structural, chemical and mineralogical patterns in a Precambrian stratifonn gold occurrence Yavapai County, Arizona, in Hausen, D.M., and Park, W.C., eds., ProcessMineralogy [Extractive Metallurgy, Mineral Exploration, Energy Resources]: American Institute of Mining and Metallurgical Engineers, BOth Annual Meeting, p. 143-157. Vance, R.K., and Condie, K.C., 1987, Geochemistry of footwall alteration associated with the early Proterozoic United Verde massive sulfide deposit, Jerome, Arizona: Economic Geology, v. 82, p. 571-586. Webb, W.p., 1979, Pr brian geology and ore deposits near Polandecam Junction, Yavapai County, Arizona: Tucson, University of Arizona, M.S. thesis, 112 p. Welty, J.W., Reynolds, S.J., Keith, S.B., Gest, D.E., Trapp, R.A., and DeWitt, Ed, 1985, Mine index for metallic mineral districts of Arizona: Arizona Bureau of Geology and Mineral Technology Bulletin 196, 92 p. Wilson, E.D., 1922, Proterozoic Mazatzal quartzite of central Arizona: Pan American Geologist, v. 38, p. 299-312. Wilson, E.D., 1939, Pr brian Mazatzal revolution ecam in central Arizona: Geological Society of America Bulletin, v. 50, p. 1131-1163. Wilson, E.D., 1961, Gold placers and placering in Arizona [6thed.], revised: Arizona Bureau of Mines Bulletin 168, 124 p. Winn, P.S., 1982, Structure and petrology of Precambrian rocksin the Black Canyon area, Yavapai County, Arizona: Salt Lake City, University of Utah, M.S. thesis, 101 p. 61