CAMBRIAN AND LATEST PRECAMBRIAN PALEOGEOGRAPHY AND TECTONICS IN THE WESTERN UNITED STATES

John H. Stewart

U.S. Geological Survey, Menlo Park, California 94025

Christopher A. Suczek Geology Department, Stanford University, Stanford, California 94305

ABSTRACT

' The upper Precambrian and Cambrian rocks of the ' crn United States are mostly shallow water Thsits that formed on a broad shelf along the jjsrn margin of the North American craton. iltively deep water deposits, some perhaps tec- j lly emplaced from distant depositional sites, =9 out in a few areas near the western margin of ffshelf. The shelf upper Precambrian and Cambrian ‘F its are divided into three main lithogenetic }~nces. These are, in ascending order: (1) a _EF-tinuous sequence, locally as much as 3,000 m :?k, of diamictite, mudstone, sandstone, conglom- _ER, and mafic volcanic rocks of Precambrian age; :a*westward-thickeningwedge, locally more than 33 m thick, of upper Precambrian and Lower '79 detrital rocks of shallow- :n terrigenous :-, in part tidal, origin; and (3) a Middle and "‘ Cambrian sequence of predominantly shallow carbonate rocks generally about 2,000 m

The rate of accumulation of strata in the _ fé eran geosyncline was apparently greatest in is Cambrian and presumably also in late 7km-rian time and decreased progressively through ‘Q cian and perhaps younger early Paleozoic time. _gate of accumulation and inferred subsidence '; s to decline exponentially with a time constant 3} t 50 m.y. Accumulation and subsidence rates jée thermal contraction in the Cretaceous to ‘}=ue Atlantic and Gulf shelves of the United ?r are also exponential with a similar time '3 nt, as are subsidence rates for oceanic crust :_ -g away from a mid-oceanic ridge. In these _f, thermal contraction followed an uplift related "E ting at a spreading center. The exponential OUTCROP OF BELT SUPERGROUP 'fi;:e in the rate of subsidence in the Cordilleran AND TEMPORALLY EQUIVALENT ROCKS “flécline suggests a similar history of thermal .s--I--‘-"'-L ‘5‘ tion after some initial heating event, perhaps *1» to fragmentation and reshaping of the western APPROXIMATE WESTWARD EXTENT OF OUTCROPS "'6 of the United States by rifting in the late OF PRECAMBRIAN CRYSTALLINE BASEMENT ROCKS _§:~rian. The diamictite and volcanic sequence A "7-e been deposited in a rift valley formed ISOLATED OUTCROP OF PRECAMBRIAN ;h an early stage of the rifting; the terrige- CRYSTALLJNE BASEMENT ROCKS Jfiatrital be related to erosion of sequence may ‘RR T7w:1ly expanded area near the rift, and the 7h:te to shallow-water shelf SAN ANDREAS FAULT sequence widespread 'f;utation after destruction of the thermally ARROWS INDICATE RELATIVE MOVEMENT §_ed area by cooling and thermal contraction and ‘R-sion. Figure 1. Distribution of crystalline basement INTRODUCTION rocks (2,400-1,450 m.y.) and Belt—age (1,450-900? m.y.) unmetamorphosed sedimentary and volcanic rocks $4: upper Precambrian and Cambrian rocks of the in the western United States. Based in part on King Tfif- United States consist of as much as 10,000 m (1976) and Armstrong(l975). 2 STETM4Rfl'.4AM7 SUKEHHK

.,, DEATH VALLEY SCHELL CREEK HUNTSVILLE POCATELLO METALINE :1: CALIFORNIA RANGE UTAH IDAHO DISTRICT :3 NEVADA wAsHINSToN U1 2 0RDOV|ClAN O a 7 O 1 °- 2 E -I 5 LIMESTONE

I % ._._,__._:, 3.3.3.3-‘.3 DOLOMITE 1 ';"_"___'.'_': 712" - E32522 '._' vn7.£S7Al

_ '. SANDY DOLOMITE

-"‘5_“'_“' SHALE on ARGILLITE _ '.°-"5.f3'.*’3.“ "33 ‘ )4 no a '.:|

0 00 O CONGLOMERATE

j___?__fi ? 3 ‘AAAAGAAA,¢,A J DIAMICTITE lvvvw/_VVVV MIDDLE AND 5. UPPER CAMBRIAN v0LcAN|C ROCK CARBONATE SEQUENCE

' 4. TERRIGENEOUS DETRITAL 1": SE°”E”°E DIABASE SILL °" 3. DIAMICTITE AND voLcANIc _____ ;,__\—‘__,‘, SEQUENCE 3w‘-‘-' GNEISS AND SCHIST 2. BELT SUPERGROUP AND TEMPORALLY EQUIVALENT ROCKS

I. PRECAMBRIAN CRYSTALLINE BASEMENT

Figure 2. Generalized diagram showing lithologic types and correlation of late Precambrian and Cambrian strat at selected localities in the western United States. Sources of data: Death Valley, Hazzard (1937), Stewart (1970), Wright, Troxel, Williams, Roberts, and Diehl (1974); Shell Creek Range, Young (1960), Hose and Blake (1976); Huntsville, Crittenden and Wallace (1973), Sorensen and Crittenden (1976); Pocatello, Trimble (1976); Metaline district, Park and Cannon (1943), Dings and Whitebread (1965), and Yates (1976). of generally shallow water sediments deposited on a States, and of relatively unmetamorphosed sedimen-1 broad shelf. This paper describes the paleogeo- tary and volcanic rocks of the Belt and of the United Supergroup graphy western States during late temporally equivalent rocks (Fig. 1). The Belt Precambrian and Cambrian time, as well as the Supergroup and temporally equivalent rocks occur tectonic events that led to the deposition of this deep epicratonic troughs, some containing as much thick sequence of rocks. This report focuses on three major sequences of Precambrian and Cambrian rocks: an upper Precambrian diamictite and volcanic sequence (900? to 800? m.y.), an uppermost Precambrian and Lower Figure 3. Distribution and maximum thickness Cambrian terrigenous detrital sequence (650? to 540 of Precambrian (900?-800? m.y.) diamictite and m.y.), and a Middle and Upper Cambrian carbonate volcanic sequence in the western United States. sequence (540-S00 m.y.). Rocks older than these Based on many sources, including Cohenour (1959), sequences consist of Precambrian crystalline meta- Wright and Troxel (1967), Crittenden, Scheaffer, morphic and intrusive rocks (about 2,400 to 1,450 Trimble, and Woodward (1971), Miller and Clark m.y.), the oldest rocks in the western United (1975), and Yates (1976). CAMBRIAN AND LATEST PRECAMBRIAN PALEOGEOGRAPHY 3

-v I3l° 121°

DCCURRENCE or DIAMICTITE ' AND VOLCANIC szomzncz 59 u Major outcrop

X Isolated outcrop

GI Drill hole ‘S

V .5. mnc VOLCANIC ROCK /A p

4 .STEMU4R7' AND SUCZEK

and consist of flows, breccias, 20,000 m of sediment (Harrison and others, 1974), or primarily greenstone and minor amounts of tuff (Crittenden and others, are widespread, relatively thin shelf deposits. Miller and Pillow More detailed information on the crystalline base- 1971; Clark, 1975; Yates, 1976)., ment rocks and the Belt Supergroup and temporally greenstones are reported locally (Aalto, 1971; equivalent rocks is given elsewhere (Harrison and Stewart, 1972; Crittenden and Wallace, 1973). others, 1974; King, 1976). Although the greenstone is highly altered, much of it seems to have been a basalt that was perhaps in DIAMICTITE AND VOLCANIC SEQUENCE (900? T0 800? M.Y.) part tholeiitic (Stewart, 1972; Miller and Clark, 1975; Yates, 1976). The diamictite and volcanic sequence consists The age of the diamictite and volcanic se- is known. The direct is of as much as 3,000 m of diamictite, mudstone, quence poorly only dating argillite, sandstone, and conglomerate, and locally of greenstone in northeastern Washington; where thick units of volcanic rocks. The highly distinc- potassium-argon ages on whole rocks and mineral tive diamictite (a rock composed of large clasts set separates are between 827 and 918 m.y. (Miller and in a finer grained matrix) is considered to be of others, 1973). The of striated glacial origin. The sequence was grouped by Stewart presence dropstones, clasts, (1972) with the overlying terrigenous detrital and massive diamictite suggests a glacial origin for of the rocks in the diamictite and sequence but is here described separately because of many sedimentary its possible tectonic importance. volcanic sequence (Aalto, 1971; Crittenden and Aalto indicates a In some areas, the diamictite and volcanic Wallace, 1973). (1971) glacial marine environment with unstratified sequence rests unconformably on crystalline basement along a coast, till inland and flow rocks, whereas in other areas it rests unconform- subglacial turbidity deposits oceanward. ably, for the most part, on the Belt Supergroup and temporally equivalent rocks. Near the United In the Death Valley region of eastern States-Canada border, the Belt Supergroup and California, the diamictite and volcanic sequence accumulated in a fault-bounded or equivalent Purcell Supergroup of Canada were apparently trough uplifted and mildly folded during the East Kootenay rift valley basin. Here the diamictite-bearing Peak Formation in thickness from 0 orogeny (White, 1959) before deposition of the Kingston ranges to over m.within a few kilometers. An area diamictite and volcanic sequence. 1,800 formation In the western United States, the diamictite close to the presumed margin of the con- tains blocks slide as and volcanic sequence is recognized in the north- gigantic (presumably blocks) and These eastern Washington and northern Idaho area, as well much as 300 m long (Wright others, 1974). relations seem best if the Peak as in southern Idaho, north-central and westernmost explained Kingston Utah, and eastern California (Figs. 2 and 3). In was deposited in a fault-bounded basin. Such an has been and others each of these areas, it is the only unit in the origin proposed by Wright Precambrian and Paleozoic sequence that contains (1974), although they call this feature an aulacogen diamictite, and in most of these same areas it is and suggest that it first developed during deposi- the only unit that contains abundant volcanic tion of the Belt—age Crystal Spring and Beck Spring rocks. These characteristics suggest that its Formations underlying the Kingston Peak Formation. correlation from region to region in the western They indicate, however, that the main stage of United States is reasonable (Crittenden and others, subsidence in the aulacogen occurred during the 1972; Stewart, 1972). In addition, the diamictite deposition of the Kingston Peak Formation. Several in the and Beck and volcanic sequence occurs at approximately the units Crystal Spring Spring Formations are uniform in the Death same stratigraphic position in each area; that is, remarkably area and were above the Belt Supergroup or rocks correlated with Valley perhaps originally widespread shelf In the Peak it on the basis of radiometric dating or the types deposits. addition, Kingston of algal structures, and below terrigenous detrital Formation contains debris derived from the Crystal rocks that contain Lower Cambrian fossils in the Spring and Beck Spring, indicating that these two formations were at one time more than upper part. The correlation is also reasonable if widespread the diamictites represent glacial deposits formed their present outcrop area. We feel that the evidence for a to the of the during a relatively short glacial epoch. Nonethe- trough prior deposition less, correlation of the diamictite and volcanic Kingston Peak is equivocal and that the Crystal and Beck are in the Death unit is not conclusively established; the unit is Spring Spring preserved discontinuous and radiometric dating has been Valley area only because they were downfaulted completed only in Washington (Miller and others, 1973). The diamictite and volcanic sequence is a laterally intertonguing complex of massive diamic- tite, boulder mudstone, laminated argillite, and Figure 4. Distribution, generalized thickness, of and Lower Cambrian minor sandstone and conglomerate, all associated and facies upper Precambrian with mafic volcanic rocks (Aalto, 1971; Crittenden (650?-540 m.y.) terrigenous detrital sequence in the and Wallace, 1973; Wright and others, 1974). The western United States. East of the 300-m isopach for the entire basal diamictites commonly contain large clasts, many of line, the thicknesses shown are Cambrian detrital unit, even in which are a meter or more across, of locally derived terrigenous though includes Middle Cambrian rocks. Crittenden and Wallace (1973) report drop- places this unit probably rocks and be or entirely stones, as large as 2 m in size, showing penetrative locally may predominantly deformation of enclosing laminae. Striated clasts Middle Cambrian in age. Based on many sources Beutner and Scholten occur but are not abundant. In thick basinal including (1967), Ruppel, Ross, and Schleicher (1975), Hobbs, and Ross (1968), sequences, the diamictites form well-graded turbi- Hays, dites. Miller (1970), Stewart (1970, 1974), Crittenden, and Woodward Lochman- Volcanic rocks occur interlayered with the Schaeffer, Trimble, (1971), Balk Oriel and (1971), sedimentary rocks and in the region near the United (1971, 1972), Armstrong Crittenden and Wallace Hintze States-Canada border occur in a unit, as much as (1973), (1973), Stewart and Poole (1975), Zen and Dutro (1975), and 2,800 m thick, overlying diamictite and associated Yates sedimentary rocks (Fig. 2). The volcanic rocks are (1976).

CAMBRIAN AND LATEST PRECAMBRIAN PALEOGEOGRAPHY 5

In’ 121‘ 124° 121°

a%.‘ . - 2% “”.h.“*?7*

Thlta point showing area of ' “%f' soutcrop and thickness, where $"i

'1' . known, in hudreds of meters. i?1us sign indicates incomplete '%hickness. Plus and minus »5Iign indicates approximate ‘thickness

aG3Q= _§pproximate 300 m isopach

A Archeocyathid locality ;

?’ Basalt or mafic volcanic rock

0 Scott . Canyon Formation FACIES E Cratonal , ‘ [[1]] Kfyrtzite and siltstone g£'tstone, carbonate and quartzite

rianlts same as 1 figure 3

SCALE ”VEK* .- F}o I00 I50 zoo MILES

“ h-.., .'100 200 KILOMETERS ‘~" ‘K . 7oNuc P ROJECTION ' *4‘

._|_ L 124° 121° *_ Caption on adjoining page. 6 $TEW%4R7'.AAM) SUKIMfl( during development of the fault-bounded basin and pebbles of quartz and quartzite, is sparsely preserved below the Kingston Peak Formation. distributed in the quartzite. Limestone and dolo- ' Late Precambrian normal faulting has been mite are present in layers less than a meter to a described also in southern Canada near the inter- few hundred meters thick. Individual units of national boundary by Price and Lie (1975). Although quartzite, siltstone, or carbonate persist for the exact relation of the diamictite and volcanic hundreds of kilometers along the trend of the sequence to the faulting is not described, the miogeocline (Stewart, 1970; Crittenden and others, diamictite and volcanic sequence is locally thick in 1971), but are less persistent and more likely to southern Canada and its distribution and thickness change facies across the trend of the miogeocline. trends could be fault related. Price and Lis Thin mafic lava flows (Fig. 4), mostly basalt, (1975) indicate that the Belt-Purcell Supergroup, occur in the terrigenous detrital sequence at some below the diamictite and volcanic sequence, was localities in Nevada and Utah (see localities offset with a maximum stratigraphic separation of 13 listed in Stewart, 1972; also Stewart, 1974). One km before it was unconformably overlapped by so- mafic volcanic breccia in Utah is dated radiomet- called "Eo-Cambrian beds," apparently the terri- trically as 570 m.y. old (Crittenden and Wallace, genous detrital sequence above the diamictite and 1973). volcanic sequence. A somewhat different facies of the terrigenous Elsewhere in the western United States, the detrital sequence occurs in the Great Basin in origin of the basins in which the diamictite and eastern California and southern Nevada (Fig. 4). volcanic sequence accumulated is uncertain. In Here the terrigenous detrital sequence is finer Utah, the diamictite locally fills a 400-m deep grained, richer in carbonate, more fossiliferous, basin (Crittenden and others, 1952) in the upper and thicker than the sequence to the east. This part of the Big Cottonwood Formation (a unit tem- facies consists mostly of siltstone, conspicuous porally equivalent to the Belt Supergroup). This carbonate units, and fine-grained quartzite. It is basin, however, is entirely erosional, and the same best developed in the Inyo-White Mountains region subunits in the Big Cottonwood Formation can be of California (Nelson, 1962; Stewart, 1970). mapped on either side of the basin (Crittenden and Fossils include trilobites, archeocyathids (Fig. others, 1952). Except for Death Valley and the 4), pelecypods, echinoderms, pelmatozoan debris, Canadian areas described above, faulting is not Hyolithes, Salterella, Skolithus, and algae known or suspected to be a factor in the development (Stewart, 1970; Palmer, 1971; Alpert, 1976; of the basins in which the diamictite and volcanic Gangloff, 1976; Nelson, 1976). In contrast, sequence was deposited, although evidence of such fossils generally are extremely rare in the terri- faulting would be difficult to see elsewhere because genous detrital sequence elsewhere in the western of the sparsity of outcrops of rocks of this age. United States. The terrigenous detrital sequence is generally_ TERRIGENOUS DETRITAL SEQUENCE (650? T0 540 M.Y.) only a few hundred meters thick in the eastern part‘ of the western United States (Fig. 4). It thickens Upper Precambrian and Lower Cambrian rocks in westward to locally over 6,000 m. ‘ the western United States consist of a west- The terrigenous detrital sequence is domi- thickening wedge of terrigenous detrital rocks nantly of shallow-water origin as is indicated by of and siltstone and minor the abundance of such shallow—water forms composed quartzite presumed , conglomerate (Figs. 2 and 4). This entire sequence as algae and archeocyathids and by the local occur- of upper Precambrian and Lower Cambrian rocks is rence of mudcracks, raindrop imprints, and runzel considered together here, because the sequence is marks (Barnes and Klein, 1975; Klein, 1975) that lithologicallysimilar, both within individual indicate local exposure. The occurrence of her- stratigraphic sections and in different regions. ringbone cross stratification, reactivation sur- Although the sequence can be divided into distinc- faces, superimposition current ripples on larger tive formation in some regions, interregional current ripples, flaser and lenticular bedding, and correlations of these formations are not complete. other sedimentary structures as well as trace Correlations are complicated by the lack of fossil fossils indicate that sediments deposited by tidal control in the Precambrian and by the sparsity, currents (Stewart, 1970; Barnes and Klein, 1975; except in a few areas, of Lower Cambrian fossils. Klein, 1975) occur in some units. other units To describe the Lower Cambrian rocks separately from appear to be subtidal sand bodies. the upper Precambrian is not practical because of the uncertainty in the location of the Precambrian- MIDDLE AND UPPER CAMBRIAN CARBONATE SEQUENCE Cambrian boundary. Even in the southern Great (540 T0 500 M.Y.) Basin, where fossil information is most complete, there is disagreement as to where to place this The name "carbonate sequence" is used in this boundary (Nelson, 1962; Cloud and Nelson, 1966; report (Fig. 2) for rocks of Middle and Late Stewart, 1970; Cloud, 1973). Cambrian age which consist primarily of limestone The terrigenous detrital sequence typically consists of cliff—forming fine- to medium-grained quartzite units from 25 to 100 m thick separated by units of siltstone and very fine to fine-grained quartzite from 15 to 300 m thick. The fine- to Figure 5. Distribution, generalized thickness, medium-grained rocks are mostly subarkose and and facies of Middle Cambrian strata in the weste orthoquartzite (Lobo and Osborne, 1976). Cross United States. Facies patterns are generalized strata of both trough and tabular planar types are and the facies shown at a locality are an average common and indicate dominantly westward transport for the entire Middle Cambrian. Based on many (Seeland, 1968, 1969; Stewart, 1970), although sources including Hazzard and Mason (1936), Robin) herringbone cross stratification in some units in (1959), Young (1960), Beutner and Scholten (1967), the southern part of the Great Basin indicates Riga (1968), Lochman-Balk (1971, 1972), Oriel and- bipolar reversals of flow directions (Diehl, 1974; Armstrong (1971), Albers and Stewart (1972), Hint Barnes and Klein, 1975, Klein, 1975; Lobo and (1973), Armstrong (1975), Stewart and Poole (1975 Osborne, 1976). Conglomerate, which contains and Yates (1976). I27 m m m us 112

0 ,_ ‘\ ‘ I: Data point. Thickness in 2".“

S7IflMAl?T ARM) Sbmiflfli and dolomite. These rocks represent a marked the result of a shallow shelf in eastern areas fol- change in lithology from the underlying terrigenous lowed to the west in turn by carbonate shoals, a detrital sequence of late Precambrian and Early deeper water open shelf, and a basinal slope (Palmer Cambrian age. The Middle and Upper Cambrian rocks 1971; Kepper, 1972, 1976; Cook and Taylor, 1975; of the carbonate sequence are described separately Taylor and Cook, 1976; Palmer and Campbell, 1976). below. The position and shape of the shoal changed con- tinuously throughout this time span, producing an Middle Cambrian rocks interfingering pattern with rocks of the shallow shelf. The position of the deeper shelf and slope Middle Cambrian rocks consist mostly of remained more stable, although the broad embayment dolomite and limestone with some shale and quartz- of deeper facies rocks into the shoal area (Fig. 5) ite. During the Middle Cambrian, the transgression did not begin until late Middle Cambrian and con- of the sea onto the craton that began in the late tinued into early Late Cambrian time. Depositional Precambrian continued. The thickness of these rocks patterns were also affected by the general eastward followed the same general pattern as underlying transgression of the sea. As the shoreline advanced rocks, with sediments thin in the east and thicken- toward the east, the deposition of sand in any one. ing towards the west (Fig. 5); but the total thick- place gave way gradually to silt and clay, and then, ness is commonly less. In the western part of the to carbonate (Lochman, 1957; Scholten, 1957; region the thickness of the Middle and Upper Lochman-Balk, 1971; Palmer, 1971). Several thin Cambrian rocks together is only a third that of the widespread deposits of terrigenous sand and silt : upper Precambrian and Lower Cambrian rocks. occur in Middle Cambrian rocks (Robison, 1960) and Middle Cambrian carbonate and shale are moder- may be related to local nearshore uplifts (Palmer, ately fossiliferous and, as a result, correlations 1956) or to a temporary marine regression which I ' and dating are better than in the Lower Cambrian. allowed sediment to be transported farther to the Trilobites,brachiopods, algae, and ichnofossils are west than usual (Kepper, 1972). the main fossil types; mollusks, conodonts, and sponges occur more rarely. Dating is based on Upper Cambrian rocks established trilobite zones, but facies changes complicate the problem of age assignment. Bound- The pattern of carbonate deposition typical of aries of some trilobite zones originally thought the Middle Cambrian continued into the early Late to be time boundaries may actually be facies Cambrian (Dresbachian), with facies patterns boundaries with fossil differences due to change in similar to those shown in Figure 5. Eastward biofacies rather than time (Lochman, 1957; Robison, transgression of the sea continued (Lochman—Balk, 1976; Palmer and Campbell, 1976). Although compli- 1972). During the latest Dresbachian and earliest cated by this facies problem, control on the Middle Franconian stages, however, a brief regression Cambrian—Upper Cambrian boundary generally is good, occurred, and shale and sandstone layers as thick except in western and northern exposures where as 60 m were deposited, temporarily extending inne structures are complex. The base of the Middle detrital belt sedimentation as far west as eastern Cambrian is more difficult to locate because the Nevada (Lochman, 1957; Palmer, 1971). When trans- Lower Cambrian sections are so sparsely fossili- gression resumed, carbonate sedimentation did also ferous. Here correlations are based on similar- and was more widespread than before. The embaymen ities of lithic content and sequences of units, and of silty rocks in eastern Nevada and western Utah the boundary is only approximately located in many that characterized the Middle Cambrian did not areas. Sedimentation was generally continuous exist after earliest Franconian time. The facies across the Lower-Middle Cambrian boundary. patterns shown on Figure 6 are for post-earliest Palmer (1960, 1971) showed that three distinct Franconian time, after the destruction of this lithofaciesbelts (inner detrital, middle carbonate, embayment. ' and outer detrital) could be recognized for the Correlation of Upper Cambrian rocks is based Upper Cambrian of the western United States. generally on trilobite and conodont zonation, Robison (1960) applied this concept to the Middle although dating based on brachiopods is nearly and Besides Cambrian. In the western United States, the inner established (Rowell Brady, 1976). detrital belt of the Middle Cambrian occurs only in trilobites and brachiopods, mollusks, echinoderms, Montana and Arizona (Fig. 5), where sand, silt, and algae, and sponges are relatively common, and clay, thin bedded and glauconitic (Lochman-Balk, conodonts, graptolites. and jellyfish occur more 1971), are typical deposits. rarely (Lochman, 1957; McBride, 1976; Brady and The middle carbonate belt, although dominantly Rowell, 1976). The base of the series was dis- thick-bedded to massive carbonate, contains a wide cussed under the Middle Cambrian section of this variety of rocks with complex depositional patterns report. The top of the series is generally well (Kepper, 1972). Stromatolitic boundstone, mottled defined except in the structurally complex and carbonate, thin-bedded limestone and dolomite, and relatively unfossiliferous rocks of the westernmo. thick-beddedbioclastic, oolitic, oncolitic, and pelleted grainstone and wackestone are typical. Organic and sedimentary structures include animal burrows, ripple marks, desiccation cracks, and some crossbedding. Figure 6. Distribution, generalized thickness, In the outer detrital belt, toward the west, and facies of Upper Cambrian strata in the weste‘ laminated shaly siltstone and lime mudstone are United States. Facies patterns are generalized common, and grainstone and wackestone contain and shown only for Upper Cambrian strata younger graded bedding, slump structures, and intraforma- than lowermost Franconian. Facies shown at a tional conglomerates. Chert generally is more locality are an average for the entire interval.‘ common toward the west. Volcanic rocks occur in Based on many sources including Young (1960), the Shwin Formation of the Shoshone Range in central Kellogg (1963), Hotz and Willden (1964), Beutner Nevada (Gilluly and Gates, 1965), which otherwise and Scholten (1967), Gilluly (1967), Rigo (1968), closely resembles rocks of the outer detrital belt. Lochman—Ba1k (1971, 1972), Hintze (1973), Armstr The lithofaciespatterns are interpreted to be (1975), Stewart and Poole (1975), and Yates (197' CAMBRIAN AND LATEST PRECAMBRIAN PALEOGEOGRAPHY 9

‘L13! I27 I24 121 Ill H5 H2 ? . , no.1 _ t

70 STEWART AND SUCZEK exposures. relation commonly mapped in other eugeosynclinal During Late Cambrian time after the earliest terranes in Nevada (Gilluly and Gates, 1965; Franconian, the deposits of the inner detrital belt Stanley and others, 1977). Conceivably, the only and the restricted shelf were east of the area of Cambrian part of the Scott Canyon Formation could Figure 6 because of continued eastward transgres- be the dated limestone, but the exact age relations sion of the sea. In western Montana and central of various parts of the Scott Canyon Formation are Utah characteristic deposits are medium- to thick- not presently known. bedded skeletal and oncolitic grainstone, comonly The Scott Canyon Formation may be a relatively with trough crossbeds, massive or crossbedded deep water oceanic deposit (Stewart and Poole, oolitic grainstone, and stromatolitic boundstone 1974). If so, the contained fossil material, which (Brady and Rowell, 1976; Lohmann, 1976). Much of is indicative of allow—water origin, is anomalous the rock has been dolomitized (Bick, 1966). In and must be explained either as occurring in slump westernmost Utah and eastern Nevada, post- deposits or in structurally interleaved shallow- Dresbachian rocks are mainly medium- to thick- water layer: in a predominantly deep-water deposit. bedded lime wackestone, which are characteris- Alternatively the shallow-water deposits could have tically so burrowed as to obliterate depositional been on the flanks of oceanic volcanoes. fabric. These rocks commonly crop out as massive ledges. Bioclasts in them are unbroken and un- Paradise Valley Chert and Harmony Formation sorted (Brady and Rowell, 1976). Nodular chert is common. In central Nevada, Upper Cambrian rocks The Upper Cambrian Paradise Valley Chert and are laminated dark-colored lime mudstone and Harmony Formation crop out in north-central Nevada turbidity-current and debris-flow grainstone (Fig. 6). They are in places, and perhaps every- deposits interbedded with mudstone and siltstone where, allochthonous and probably were transported (Taylor and Cook, 1976). tectonically eastward into their present position This depositional pattern is interpreted to during the Late Devonian and Early Mississippian be the result of a narrow shoal bordered on the Antler orogeny. The Paradise Valley Chert is about west by a deeper water shelf, with sedimentation 100 m thick and made up of thin-bedded chert, chert below wave base, bordered in turn by the continen- breccia, and some shale and limestone (Hot: and tal slope. The shelf was locally emergent during Willden, 1964). It is early Late Cambrian the middle Late Cambrian in western Montana, central (Dresbachian) in age and crops out only near the Idaho, and central Utah (Lochman, l957). center of the Hot Springs Range. The Harmony Formation, which probably deposi- UNUSUAL CAMBRIAN ROCKS tionally overlies the Paradise Valley Chert, crops out in north-central Nevada (Fig. 6). The thick- Three formations of Cambrian or partly Cambrian ness of the Harmony has been estimated to be from age in north-central Nevada are so different litho- 600 to 1,300 m, although the top of the formation logically from any other Cambrian units in the is not exposed and structural complexities make western United States that they are described thicknesses uncertain. The Harmony is composed of separately here. One of these, the Scott Canyon feldspathic sandstone and siltstone, with shale, Formation, is considered part of the siliceous and minor limestone, and minor pebble conglomerate. volcanic (eugeosynclinal) assemblage of Nevada and The composition of the sandstone is variable, with is somewhat similar lithologicallyto Ordovician, quartz constituting 50-80 percent of the grains, Silurian, and Devonian eugeosynclinal rocks in feldspar 10-30 percent, and mica, heavy minerals, Nevada. The Paradise Valley Chert and Harmony and lithic clasts (mostly quartzite, chert, and Formation, although they have been classified as argillite) the remainder (Suczek, 1977). Potsssi parts of the eugeosynclinal assemblage (Stewart and feldspars (orthoclase and microcline) and plagia- Poole, 1974), are difficult to relate to other clase both occur, indicating a plutonic or gneiss rocks in the western United States. The Harmony source rock; radiometric dating of zircon (Jaffe contains abundant feldspathic sandstone and is not and others, 1959) indicates the source rocks of th like any other lower Paleozoic eugeosynclinal unit Harmony were Precambrian in age. Sandstone layers in Nevada. These three units are the only Cambrian in the Harmony are considered to be midfan turbi- eugeosynclinal, or possibly eugeosynclinal, rocks dite deposits (Suczek, 1977) and probably were known in the western United States. deposited on a continental rise. Trilobitesfrom limestone date the Harmony as Scott Canyon Formation middle and late Late Cambrian (Franconian and Trempealeauan). These fossils are similar, taxo- The Scott Canyon Formation crops out (Fig. 4) nomically and texturally, (M. E. Taylor, written in the Battle Mountain area of north-central comun., 1977) to the redeposited tribolites of Nevada (Roberts, 1964). It is allochthonous and lower part of the Hales Limestone (Taylor, 1976) probably was transported eastward 80 km or more to central Nevada. These taxa show affinities to the its present position during the Late Devonian and North American faunal province (A. R. Palmer, oral Early Mississippian Antler orogeny. It is composed commun., 1976; M. E. Taylor, written comun., 1977 of several thousand meters of radiolarian chert, and suggest that the Harmony was deposited near t argillite, and greenstone (in part pillow lavas) shallow carbonate shelf and that the fauna was and minor amounts of sandstone, quartzite, and transported into deep water. limestone (Roberts, 1964; Theodore and Roberts, 1971). The limestone occurs in lenses and contains SUBSIDENCE PATTERNS DURING LATE PRECAMBRIAN algae, sponges, archeocyathids, and trilobites AND EARLY PALEOZOIC TIME considered to be of Early or Middle Cambrian age. Recently, however, radiolarian in chert from the Because most of the upper Precambrian and lo Scott Canyon Formation have been tentatively Paleozoic miogeoclinal rocks in the western Unit assigned a Devonian age by Brian Holdsworth (written States were deposited in shallow water (Lochan- commun., 1977). This discovery suggests that the Balk, 1972; Stewart and Poole, 1974) and are not Scott Canyon may consist of structurally inter- related to the progressive infilling of an initia leaved rocks of at least two ages, a structural deep basin, the accumulation of the thick upper

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THICKNESS 5 F MIN|MUM— MAXIMUM-I 7s I’ I at { I --50 um. EXPONENTIAL CUMULATIVE 9- f u 1 THICKNESS '°f -APPROXIMATE TOTAL CAMBRIAN AND LATEST PRECAMBRIAN PALEOGEOGRAPHY 73

MAXIMUM ORIGINAL EASTWARD EXTENT

Trempealeauan Stage (upper Upper Cambrian)

Franconian Stage _ Kniddle Upper Cambrian)

I J Dresbackian Stage f"- er Upper Cambrian) - D .‘ - Q ..'¢—- Upper Middle Cambrian

’l-Ijlf’ iawer Middle Cambrian fl"‘-in 15'3"‘: Lower Cambrian V; IZED DISTRIBUTION OF *avoUs DETRITAL SEQUENCE {ya IT IS GREATER THAN ‘ 300 m THICK H 0 200M|los an 0 200 Km Izajnj-ul--I

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Figure 10. Distribution of miogeoclinal upper Precambrian and Lower Cambrian terrigenous detrital sequence and maximum original eastward extent of Middle and Upper Cambrian stages in the western United States (in part after Lochman—Ba1k, 1972).

;fq~ same position as it was for later these rift valleys formed along lines of weakness '{3an miogeoclinal deposits (Gabrie1se, 1972; that were later to become the main site of conti- g3» others, 1972; Seyfert and Sirkin, 1973; nental rifting. fgzand others, 1974; Harrison and Reynolds, In the model proposed, the terrigenous detrital inc, 1976). The relative merits of the pre- sequence is related to erosion of the initial rift ;ppost-Belt rifting hypotheses have been bulge (uplifted area) that was created by thermal “hépreviously by Gabrielse (1972), Monger, expansion during the continental rifting. Such ‘:.-- Gabrielse (1972), Burchfiel and Davis uplift is well known along the Afro-Arabianrift ‘a. Stewart (1976) and will not be reviewed system (Baker and others, 1972; Kinsman, 1975; f;; geologists (Burchfiel and Davis, 1975; Lowell and others, 1975). The cessation of deposi- j, 1977) have discussed the possibility that tion of terrigenous detritus in the miogeocline is (git occurred in both pre—Belt and post-Belt related to the destruction of the bulge by thermal ‘fl;= incorporating elements of both hypo- contraction due to cooling and by erosion. After the bulge had been lowered to a certain level, the ‘E~g-el proposed here (Fig. 9) differs ocean transgressed eastward (Fig. 10) into cratonic “§=»~ that proposed by Stewart (1972, 1976) areas. As a consequence, coarse detrital material 'fl.incorporates the concept that the diamic- was trapped in coastal areas on the craton and the gglcanic sequence may have accumulated miogeoclinal shelf was an area of carbonate deposi- 7U_rift-valley basins that formed prior to tion relatively free of detritus. .I‘ :ge of rifting. The timing of these ‘jg;--rly known, but the rift valleys may PALEOGEGRAPHY ;g« from 800 to 900 m.y. ago and the main §Lgqt‘not until perhaps 650 m.y. ago. The dominant paleogeographic pattern in the ‘agkke (oral commun., 1976) has noted that western United States during the late Precambrian ‘Ly. eye, such as the Oslo graben in and Cambrian was a broad shallow-water shelf extend- Vggeo at a significantly earlier time than ing along the western margin of the North American 5§gtinental rifting. He suggests that craton. Land areas lay to the east and a deep-water 74 STEWART AND SUCZEK

ocean basin to the west. The shelf sediments are of the Harmony could have been derived from rocks miogeoclinal deposits similar to those that accumu- of the uppermost Precambrian and Lower Cambrian lated during the Cretaceous and Cenozoic along the terrigenous detrital sequence exposed along the eastern margin of North America (Stewart and Poole, continental slope, although in general these older 1974). Most of the preserved upper Precambrian and detrital rocks do not contain sufficient feldspar Cambrian rocks in the western United States are to be a source for the Harmony. Still another shallow-water sediments that comprise the miogeo- possibility is that Precambrian crystalline base- cline. The eugeosynclinal Scott Canyon Formation, ment rocks exposed on the continental slope or in which may be only partly Cambrian in age, includes some area of local uplift (Erickson and Marsh, abundant chert and greenstone and is interpreted to 1974) could have been a source for the Harmony. be a deep-water ocean basin deposit formed west of Finally, the Harmony could have come from a western the shelf and tectonically emplaced over the shelf source area separated from North America by an sediments presumably during the mid-Paleozoic ocean basin or a marginal sea. The Harmony would Antler orogeny. Some Middle and Upper Cambrian have been emplaced on North America when this land units contain abundant carbonate slump breccia and (perhaps a microcontinent or island arc} collided relatively deep water trilobites (Taylor and Cook, with North America. The concept of a foreign’ 1976) and probably accumulated on the upper part of source for the Harmony, however, is not supported the continental slope between the shelf to the east by the affinity of the fauna in the Harmony to the and the lower slope and upper continental rise to North American faunal province, a relation that the west. Middle and Upper Cambrian units generally suggests that the Harmony was deposited near the are shaly and cherty near the western margin of the North American shallow shelf. miogeocline, and these units may also have accumu- In summary, the paleogeographic setting of the lated near the shelf edge or on the upper part of diamictite and volcanic sequence is not clear, but the continental slope. this sequence may have accumulated in part in Cambrian paleogeography west of the conti- rift valleys. By the time the terrigenous detrital nental slope and rise is unknown. The oldest rocks sequence was deposited, however, the shelf margin to the west are Ordovician in the northern Sierra of the western United States was well defined, and Nevada, Ordovician in the Klamath Mountains, this paleogeographic pattern continued into the Devonian in central and eastern Oregon and Ordovician Devonian. If the establishment of this shelf in northwestern Washington and adjacent parts of margin was related to rifting, a highland caused by British Columbia. The oldest Ordovician rocks in thermal expansion probably existed to the east of the Klamath Mountains and northwest Washington are the miogeocline in the latest Precambrian and Early ophiolite complexes (Hopson and Mattinson, 1973), Cambrian time and was a source of much detritus. which clearly indicate a post—Cambrian origin of By the end of Early Cambrian time, the highland was most of this westernmost region of the United largely destroyed by erosion and thermal contrac- States. tion, allowing the sea to transgress slowly eastwa In east-central Idaho, an unusual feature of over areas that were previously land. During the the Cambrian paleogeography is a topographically Late Cambrian, seas extended 600 to more than 1,000 high area, called the Lemhi arch (Figs. 4-6) by km (Fig. 10) east of the eastern margin of the Sloss (1954) and the Salmon River arch by Armstrong miogeocline, and much of the western United States (1975) that separates the Cordilleran miogeocline was a shallow sea. from the shelf to the east. Within this arch, Ordovician rocks locally rest unconformably on ACKNOWLEDGMENTS rocks temporally equivalent to the Belt Supergroup (Beutner and Scholten, 1967; Ruppel and others, We wish to thank R. K. Hose, D. H. Whitebread, 1975; Ruppel, 1976). Precambrian crystalline and M. E. Taylor for their helpful comments on the basement rocks presumably were exposed in the arch manuscript. In addition, A. R. Palmer and during Cambrian time and are a probable source for M. E. Taylor helped by pointing out the affinities of some feldspar-rich detrital units in north-central of the fauna from the Harmony Formation to that Idaho and perhaps elsewhere. the North American faunal province. M. E. Taylor The source of the feldspathic detrital material brought to our attention some aspects of the possi in the Harmony Formation (Upper Cambrian) of north- relation of the Harmony Formation and Worm Creek central Nevada is conjectural. All other units of Quartzite Member of the St. Charles Limestone to comparable age in Nevada are composed predominantly the Lemhi arch. of carbonate and shale. In northern Utah and Suczek's work on the Harmony Formation has southeastern Idaho, however, shelf rocks contain a been partially supported by Geological Society of feldspar-rich quartzite unit, the Worm Creek America Penrose Bequest Research Grants 2020-75 Quartzite Member of the St. Charles Limestone and 2144-76 and a Grant in Aid from the American (Haynie, 1957; Armstrong and Oriel, 1965; Trimble Association of Petroleum Geologists. and Carr, 1976). This unit is Late Cambrian, the age of the Harmony. In east-central Idaho, the REFERENCES CITED Clayton Mine Quartzite, which is of uncertain age but lies below rocks of Middle Ordovician age and Aalto, K. R., 1971, Glacial marine sedimentation apparently above structurally separated rocks of and stratigraphy of the Toby Conglomerate (up Middle Cambrian age, is also feldspathic (Hobbs and Proterozoic) southeastern British Columbia, others, 1968). Thus, the sandstone of the Harmony northwestern Idaho, and northeastern Washingto possibly was derived from the same source area as Canadian Jour. Earth Sci., v. 8, no. 7, p. 75 the Worm Creek and Clayton Mine quartzites. Such a 787. source might have been Precambrian rocks exposed in Albers, J. P., and Stewart, J. E., 1972, Geology the Lemhi (Salmon River) arch in east-central Idaho and mineral deposits of Esmeralda County, Nev 80 or on the craton to the east of Idaho or northern Nevada Bur. Mines Geology Bull. 78, p. Utah. If so, detrital material may have been Alpert, S. P., 1976, Trace fossils of the White- transported across the shelf in Idaho and from Inyo Mountains, in Moore, J. N., and Fritsche,- there southward in deeper water west of the shelf E., eds., Depositional environments of lower into north-central Nevada. Alternatively, the sand Paleozoic rocks in the White-Inyo Mountains, Q-..ty, California: Soc. Econ. Paleontologists ;}» Mineralogists, Pacific Sec., Pacific Coast Paleogeography Field Guide 1, p. 43-48. ,j_ ong, F. C., and Oriel, S. S., 1965, Tectonic jewelopment of Idaho-Wyoming thrust belt: Am. ,,:oc. Petroleum Geologists Bull., v. 49, no. 11, 3. 1847-1886. jtrong, R. L., 1975, Precambrian (1,500 m.y. jld) rocks of central Idaho--The Salmon River gfch and its role in Cordilleran sedimentation :5 tectonics, in Ostrom, J. H., and :1-ille, P. M., eds., Tectonics and mountain ’,»;es: Am. Jour. Sci. (Rodgers Volume), v. 275- T, p. 437-467. fa, B. H., Mohr, P. A., and Williams, L. A. J., 1#72, Geology of the eastern rift system of _}rica: Geol. Soc. America Spec. Paper 136, 67 ifiy, J. J., and Klein, C. deV., 1975, Tidal lgposits in the Zabriskie Quartzite (Cambrian), gtrtern California and western Nevada, in Ginsburg, :¢.N., ed., Tidal deposits: New York, Springer- it lag, p. 163-169. E. and g« , C., Scholten, Robert, 1967, Probable '{y-rian strata in east-central Idaho and their "3 eotectonic significance: Am. Assoc. Petroleum _1ogists Bull., v. 51, no. 11, p. 2305-2311. f‘ K. F., 1966, Geology of the Deep Creek .} -tains, Tooele and Juab Counties, Utah: Utah "731. Mineralog. Survey Bull. 77, 120 p. A, M. J., and Rowell, A. J., 1976, Upper Cambrian .f;t1da1 blanket carbonate of the miogeocline, Titern Great Basin: Brigham Young Univ. Geology jk-ies, v. 23, pt. 2, p. 153-180. f1e1, B. c., and Davis, c. A., 1975, Nature fg_controls of Cordilleran orogenesis, western 7 ted States: Extensions of an earlier syn- 1>:is, in Ostrom, J. H., and Orville, P. M., ?Q., Tectonics and mountain ranges: Am. ’?». Sci. (Rogers Volume), v. 275-A, p. 363- ,, Kevin, and Dewey, J. F., 1973, Plume- ated 4; triple junctions: Key indicators in Qlying plate tectonics to old rocks: Jour.

1

15 STEWART AND SUCZEK } of the southern Red in A. Bull., v. 47, p. 229-240. tonics Sea, Fischer, GJ Hintze, L. F., 1973, Geologic history of Utah: and Judson, Sheldon, eds., Petroleum and global Brigham Young Univ. Geology Studies for Students tectonics: Princeton, N. J., Princeton Univ. 129-153. No. 8, v. 20, pt. 3, 181 p. Press, p. Hobbs, S. W., Hays, W. H., and Ross, R. J., Jr., McBride, D. J., 1976, Outer shelf communities and in the Upper Cambrian of the Great 1968, The Kinnikinic Quartzite of central trophic groups 1 Idaho--Redefinition and subdivision: U.S. Geol. Basin: Brigham Young Univ. Geology Studies, v. Survey Bull. 1254-J, p. J1-J22. 23, pt. 2, p. 139-152. Hopson, C. A., and Mattinson, J. M., 1973, Miller, F. K., 1970, Geologic map of the Quartzite Ordovician and Late Jurassic ophiolitic assem- quadrangle, Yuma County, Arizona: U.S. Geol. blages in the Pacific northwest: Geol. Soc. Survey Geol. Quad. Map GQ-841, scale l:62,500. and L. of America Abs. with Prog., v. 5, no. 1, p. 57. Miller, F. K., Clark, D., 1975, Geology Hose, R. R., and Blake, M. C., Jr., 1976, Geology the Chewelah-Loon Lake area, Stevens and Spokane Prof. and mineral resources of White Pine County, Counties, Washington: U.S. Geol. Survey Nevada, Part 1, Geology: Nevada Bur. Mines and Paper 806, 74 p. Geology Bull. 85, 105 p. Miller, F. K., McKee, E. H., and Yates, R. G., Hotz, P. E., and Willden, Ronald, 1964, Geology and 1973, Age and correlation of the Windermere mineral deposits of the Osgood Mountains quad- Group in northeastern Washington: Geol. Soc. Humboldt County, Nevada: U.S. Geol. America Bu1l., v. 84, p. 3723-3730. rangle, and Survey Prof. Paper 431, 128 p. Monger, J. W. H., Southes, J. G., Gabrielse, H., Jaffe, H. W., Gottfried, David, Waring, C. L., and 1972, Evolution of the Canadian Cordillera--A Worthing, H. W., 1959, Lead-alpha age deter- plate-tectonic model: Am. Jour. Sci., v. 272, # rocks 577-602. minations of accessory minerals of igneous p. ‘ (1953-1957): U.S. Geol. Survey Bull. 1097-B, Nelson, C. A., 1962, Lower Cambrian-Precambrian California: p. 65-148. succession, White-Inyo Mountains, Kellogg, H. E., 1963, Paleozoic stratigraphy of the Geol. Soc. America Bull., v. 73, p. 139-144. southern Egan Range, Nevada: Geol. Soc. America 1976, Late Precambrian-Early Cambrian strati- and faunal succession of eastern Bu11., v. 74, p. 685-708. graphy Kepper, J. C., l9]2, Paleoenvironmental patterns in California and the Precambrian-Cambrian boundary Middle to Lower Upper Cambrian interval in eastern in Moore, J. N., and Fritsche, A. E., eds., Great Basin: Am. Assoc. Petroleum Geologists Depositional environments of lower Paleozoic roc, Bu1l., v. 56, p. 503-527. in the White-Inyo Mountains, Inyo County, 1976, Stratigraphic relationships and California: Soc. Econ. Paleontologists and Pacific Pacific Coast depositional facies in a portion of the Middle Mineralogists, Sec., Cambrian of the Basin and Range Province: Paleogeography Field Guide 1, p. 31-42. Brigham Young Univ. Geology Studies, v. 23, pt. 2, Oriel, S. S., and Armstrong, F. C., 1971, Uppermost Precambrian and lowest Cambrian rocks in south- p. 75-91. King, P. B., 1976, Precambrian geology of the United eastern Idaho: U.S. Geol. Survey Prof. Paper States; An explanatory text to accompany the 394, 52 p. Geologic Map of the United States: U.S. Geol. Palmer, A. R., 1956, The Cambrian system of the Gr in Survey Prof. Paper 902, 85 p. Basin in western United States, Rodgers, John Kinsman, D. J. J., 1975, Rift valley basins and ed., E1 sistema Cambrico, su paleogeografia y sedimentary history of trailing continental el problema de su base - symposium, pt. 2: margins, in Fischer, A. G., and Judson, Sheldon, Internet. Geol. Cong., 20th, Mexico, Proc., eds., Petroleum and global tectonics: Princeton, p. 663-681. N. J., Princeton Univ. Press, p. 83-127. 1960, Some aspects of the early Upper Cambri Klein, G. deV., 1975, Paleotidal range sequences, stratigraphy of White Pine County, Nevada and Middle Member, Wood Canyon Formation (late vicinity: Intermountain Assoc. Petroleum Precambrian), eastern California and western Geologists Ann. Field Conf., llth, p. 53-58. Nevada, in Ginsburg, R. N., ed., Tidal deposits: 1971, The Cambrian of the Great Basin and in New York, Springer-Verlag, p. 171-177. adjoining areas, western United States, Lobo, C. F., and Osborne, R. H., 1976, Petrology of Holland, C. H., ed., Cambrian of the New World: late Precambrian-Cambrian quartzose sandstones New York, Wiley-Interscience, p. 1-78. in the eastern Mojave Desert, southeastern Palmer, A. R., and Campbell, D. P., 1976, Bio- California: Southern California Univ., Dept. stratigraphic implications of trilobite Geol. Sci., Contr. 357, 36 p. biofacies--Albertellazone, Middle Cambrian, Lochman, Christina, 1957, Paleoecology of the western United States: Brigham Young Univ. Cambrian in Montana and Wyoming, in Ladd, H. S., Geology Studies, v. 23, pt. 2, p. 39-50. ed., Treatise on marine ecology and paleoecologyz Park, C. F., Jr., and Cannon, R. S., Jr., 1943, Geol. Soc. America Mem. 67, p. 117-162. Geology and ore deposits of the Metaline quad- Lochman-Balk, Christina, 1971, The Cambrian of the rangle, Washington: U.S. Geol. Survey Prof. craton of the United States, in Holland, C. H., Paper 202, 81 p. ed., Cambrian of the New World, V. 1: New York, Price, R. A., and Lis, M. G., 1975, Recurrent dis- Wiley-Interscience, p. 79-167. placements on basement-controlled faults across 1972, Cambrian system, in Geologic atlas of the the Cordilleran miogeocline in southern Canada Rocky Mountain region: Denver, Colo., Rocky [abs.]: Geol. Soc. America Abs. with Prog., v. Mountain Assoc. Geologists, p. 60-75. no. 7, p. 1234. Lohmann, K. C., 1976, Lower Dresbachian (Upper Rigo, R. J., 1968, Middle and upper Cambrian strat Cambrian) platform to deep—shelf transition in graphy in the authochthonand allochthon of eastern Nevada and western Utah--An evaluation northern Utah: Brigham Young Univ. Geology through lithologic cycle correlation: Brigham Studies, v. 15, pt. 1, p. 31-66. o Young Univ. Geology Studies, v. 23, pt. 2, Roberts, R. J., 1964, Stratigraphy and structure p. 111-122. the Antler Peak quadrangle, Humboldt and Lander Lowell, J. D., Genik, G. J., Nelson, T. H., and Counties, Nevada: U.S. Geol. Survey Prof. Pap Tucker, P. M., 1975, Petroleum and plate tec- 459-A, 93 p. CAMBRIAN AND LATEST PRECAMBRIAN PALEOGEOGRAPHY I7 %ion, 0. D., 1959, The disturbed belt in the 1974, Correlation of uppermost Precambrian and lfi een-mile area, Montana: Billings Geol. Soc., Lower Cambrian strata from southern to east- 1}. Field Conf., 10th, p. 34-40- central Nevada: U.S. Geol. Survey Jour. Research, it”, B. A., 1960, Lower and Middle Cambrian v. 2, no. 5, p. 609-618. jzatigraphy of the eastern Great Basin, in 1976, Late Precambrian evolution of North ";1cgy of east-central Nevada: Intermountain America: Plate tectonics implication: Geology, Ann. Field “Ta . Petroleum Geologists, Conf., January 1976, p. 11-15. 43-52. Stewart, J. and F. Lower 5'3: p. H., Poole, G., 1974, 3976, Middle Cambrian trilobitebiostratigraphy Paleozoic and uppermost Precambrian Cordilleran ’ the Great Basin: Brigham Young Univ. Geology miogeocline, Great Basin, western United States, *gg -s, v. 23, pt. 2, p. 93-109. in Dickinson, W. R., ed., Tectonics and sedi- ‘t, A. J., and Brady, M. J., 1976, Brachiopods mentation: Soc. Econ. Paleontologists '3 biomeres: Brigham Young Univ. Geology Mineralogists Spec. Pub. 22, 57 p. "‘.":_.». 33, v, 23, pt. 2, p. 165-180. 1975, Extension of the Cordilleran miogeosyn- "1, E. T., 1976, Medicine Lodge thrust system, clinal belt to the San Andreas fault, southern “*1-central Idaho and southwest Montana: U.S. California: Geol. Soc. America Bull., v. 86, ]71. Survey Open-file rept. 76-366, 25 p. p. 205-212. E, E. T., Ross, R. J., Jr., and Schleicher, Suczek, C. A., 1977, Sedimentology and petrology of .7-, 1975, Precambrian Z and Lower Ordovician the Cambrian Harmony Formation of north-central ‘ffis in east-central Idaho: U.S. Geol. Survey Nevada [abs.]: Geol. Soc. America Abs. with gr. Paper 889-B, p. 25-34. Prog., v. 9 (In press). fjm, Robert, 1957, Paleozoic evolution of the Taylor, M. E., 1976, Indigenous and redeposited 37~-clinal margin north of the Snake River trilobites from Late Cambrian basinal environments ?$., Idaho—Montana: Geol. Soc. America Bull., of central Nevada: Jour. Paleontology, v. 50, )8, p. 151-170. p. 668-700. (Q, D. A., 1968, Paleocurrents of the late Taylor, M. E., and Cook, H. E., 1976, Continental t,:w-rian to Early Ordovician (basal Sank) shelf and slope facies in the Upper Cambrian and ;;;gressive clastics of the western and northern Lowest Ordivician of Nevada: Brigham Young Univ. ,:ed States: Utah Univ., Salt Lake City, Ph. D. Geology Studies, v. 23, pt. 2, p. 181-214. 276 Theodore, T. and R. Geo- "His, p. G., Roberts, J., 1971, “B, D. A., 1969, Marine current directions in chemistry and geology of deep drill holes at Iron Tim Precambrian and Cambrian rocks of the south- Canyon, Lander County, Nevada.wdth a section on jiern United States, in Baars, D. L., ed., Geophysical logs of drill hole DDH-2, by =:ygy and natural history of the Grand Canyon C. J. Jablocki: U.S. Geol. Survey Bull. 1318, 53:: Four Corners Geol. Soc., Field Conf., 32 p. 1+, Guidebook, p. 123-126. Trimble, D. E., 1976, Geology of the Michaud and "H, C. R., and Sirkin, L. A., 1973, Earth Pocatello quadrangles, Bannock and Power Inry and plate tectonics--An introduction to Counties, Idaho: U.S. Geol. Survey Bull. 1400, '5} ical geology: New York, Harper and Row, 88 p. Trimble, D. E., and Carr, W. J., 1976, Geology If. H., 1971, Thermal effects of the formation of the Rockland and Arbon quadrangles, Power ,;§1antic continental margins by continental County, Idaho: U.S. Geol. Survey Bull. 1399, JK up: Geophys. Jour. Royal Astron. Soc., 115 p. 9,. no. 4, p. 325-350. White, W. H., 1959, Cordilleran tectonics in British _E- H., and Snell, N. 8., 1976, Thermal Columbia: Am. Assoc. Petro1eum'Geologists Bull., ?4lction and flexure of mid-continent and v. 43, p. 60-100. 7% ic marginal basins: Geophys. Jour. Royal Wright, L. A., and Troxel, B. W., 1967, Limitations ‘fig. Soc., v. 45, p. 125-154. on right-lateral, strike-slip displacement, -;. L., 1954, Lemhi arch, a mid-Paleozoic Death Valley and Furnace Creek fault zones, element in .g-ve south-central Idaho: Geol. California: Geol. Soc. America Bull., V. 78, * America Bull., v. 66, p. 365-368. no. 8, p. 933-949. 3, M. L., and Crittenden, M. D., Jr., 1976, Wright, L. A., Troxel, B. W., Williams, E. G., :9‘ -:ry geologic map of the Mantua quadrangle Roberts, M. T., and Diehl, P. E., 1974, Jyrt of the Willard quadrangle, Box Elder, Precambrian sedimentary environments of the ‘g, and Cache Counties, Utah: U.S. Geol. Death Valley region, eastern California, in pf; Misc. Field Studies Map MT—720, scale Guidebook--DeathValley region, California and boon, Nevada, Field Trip No. 1: Geol. Soc. America, ?fR. 0., Chamberlain, C. R., and Cordilleran Sec., Ann. Mtg., 70th, Las Vegas, ’[&t, J. H., 1977, Depositional setting of Nev., 1974, p. 27-35. wuzeosynclinal Ordovician rocks and struc- Yates, R. G., 1976, Geology of the Deep Creek area, *{~ interleaved Devonian rocks in the Washington, and its regional significance: ‘tsetse mobile belt, Nevada, in Stewart, J. H., U.S. Geol. Survey Open-file rept. 76-537, 435 f7§, C. H., and Fritsche, A. E., eds., p. " ‘t- of the western J. Structure ‘—‘ United Young, and . Paleogeography C., 1960, stratigraphy in ' ' 0 ,0 Soc. Econ. Paleontologists and north-central Schell Creek Range, in _ Boettcher, ';:°gists, Pacific Sec., Pacific Coast J. W., and Sloan, W. W., Jr., eds., Guidebook ‘{{-graphy Symposium 1 (this volume). to the geology of east-central Nevada:' ~63. H., 1970, Upper Precambrian and Lower Intermountain Assoc. Petroleum Geologists, Ann. T—p strata in the southern Great Basin, Field Conf., 11th, p. 158-172. ’ig3 . and Nevada: U.S. Geol. Survey Prof. zen, E-an, and Dutro, J. T., Jr., 1975, Upper (5Vi0. 206 P- Precambrian-Lower Cambrian(?) sedimentary ,rgInitia1 deposits in the Cordilleran sequence, Pioneer Mountains, southwest Montana ,;j -:: Evidence of a late Precambrian [abs.]: Geol. Soc. America Abs. with Prog., y.“y.) continental separation: Geol. Soc. V. 7, no. 7, p. 1327. °’ Bull., v. 83, p. 1345-1360.