New geologic mapping and fossil data from the Pine Forest Range, Black Rock Desert, northwest Nevada, indicates that the range contains a structurally intact sequence of variably metamorphosed middle (and early?) Paleozoic through latest Triassic strata. The oldest rocks in the range include metamorphosed quartzo-feldspathic sedimentary rocks and mafic volcanic and volcaniclastic rocks of Mississippian and/or older age. Overlying fan facies chert/argillite/quartz-rich clastic rocks are of post–Late Devonian(?) and pre–Late Mississippian age, and are succeeded by shallower marine Upper Mississippian to Lower Pennsylvanian(?) volcanic rocks, volcanic-lithic–rich clastic rocks, and limestone. The remainder of Paleozoic time is characterized mostly by shallow marine conditions and the development of several unconformities. A thin sequence of shallow marine carbonates and clastic sediments, yielding early Late Permian fossils at the top, overlies Pennsylvanian(?) strata across an unconformity that may span early Pennsylvanian through Early Permian time. Upper Permian(?) chert and shale unconformably overlie older rocks and reflect some subsidence in Late Permian(?) time. A third unconformity separates Paleozoic and Triassic rocks and spans latest Permian(?) through Middle or Late Triassic time. Triassic strata in the Pine Forest Range record two distinct periods of deposition: (1) fan facies sedimentary-lithic–rich sediments and basinal carbonates were deposited from Ladinian or Carnian (late Middle or early Late Triassic) through early Norian (late late Triassic) time, and (2) mafic to intermediate composition lavas and associated volcanic-lithic– and crystal-rich fan facies sediments were deposited during most of the remainder of Norian time. Lavas exhibit the trace-element characteristics of volcanic arc magmas. Relatively deep marine conditions of deposition occurred throughout Middle(?) to Late Triassic time. The Paleozoic stratigraphic record in the Pine Forest Range shows important similarities to that of other Paleozoic arc sequences in the western U.S. Cordillera, including those in the northern Sierra Nevada and eastern Klamath Mountains (California), Blue Mountain province (Oregon), and Chilliwack terrane (Washington). These similarities support an interpretation of paleogeographic and tectonic ties between the Black Rock Desert and these other arc sequences in Mississippian (and early Paleozoic?) through Permian time. In addition, the presence of a Permo-Triassic unconformity in the Pine Forest Range represents new evidence that these Paleozoic arc sequences were characterized by uplift and erosion during the time of the Sonoma orogeny. Early Mesozoic strata in the Pine Forest Range provide a record of volcanism and sedimentation that is similar to that in other early Mesozoic volcanic arc sequences from the southwestern United States through northern California. These similarities support an interpretation that early Mesozoic arc sequences in northwest Nevada, as well as northern California, form the northern continuation of the west-facing early Mesozoic arc documented in the southwestern United States. In addition, the Triassic record in the Pine Forest Range suggests that extension-related intra-arc subsidence, inferred to have characterized the southwestern United States during early Mesozoic time, may also have affected early Mesozoic rocks of the Black Rock Desert.

Abstract Our studies of the Neoproterozoic Uinta Mountain Group focus on the Red Pine Shale in the western Uinta Mountains and the undivided clastic strata in the eastern Uinta Mountains, which record deltaic-marine and braided-fluvial to shoreline deposition, respectively. We conclude that the Red Pine Shale postdates the < 770 Ma eastern clastic strata, and the Uinta Mountain Group represents deposition in a rift basin predating the rift episode recorded at ~ 700 Ma in western Laurentia. Measured sections and stratigraphic mapping of the Red Pine Shale show that it is ~ 550-1200 m thick in the western part of the range, thins to < 300 m in the east-central range, and is missing in the eastern range. Measured sections show organic-rich shale interbedded with medium- to coarse-grained sandstone. Sedimentary structures include graded bedding, hummocky cross stratification, parallel to ripple lamination, tabular crossbeds, ripple marks, and slump folds. Fossils include Bavlinella faveolata, filaments, leiosphaerid acritarchs, and, more rarely, vase-shaped microfossils and ornamented acritarchs. Preliminary whole-rock δ 13 Corg analysis of organic-rich shales reveal 13.9%o (PDB) variability (values range from -16.9 to -30.8%o PDB) and TOC values range from 0.07 to 5.9%. Combined data suggest deposition below and near fair-weather wave base in a marine deltaic system, and correlation with the ~ 770 to > 742 Ma Chuar Group, Grand Canyon. The undivided clastic strata of the Uinta Mountain Group, eastern Uinta Mountains, are dominated by trough- and tabular-cross- bedded and massive sandstone showing south-southwestern paleocurrent flow. At least three laterally continuous (kilometer-scale) ~ 50-m-thick intervals of gray-green, organic-bearing shale have been mapped amongst these sandstone intervals and contain ripple marks, mud-crack casts, ripple cross laminae, and gypsum casts and molds. The lowermost shale interval allows subdivision of the clastic strata into three informal units. Fossils from shale in the middle-upper (?) interval of the clastic strata include acritarchs and possible vase-shaped microfossils. Simple sphaeromorphs and carbonaceous filaments have also been found in black to green shale near the base of the section. The clastic strata represent a sandy braid system with possible marine drowning events from the west. In addition to an alluvial-fan setting, the Jesse Ewing Canyon Formation, the basal unit of the UMG below the clastic strata, represents high-energy shoreline and fan-delta deposition.

Abstract Today we spend time in the central portion of the Sierra Nevada batholith, mapped here in detail by Moore (1963) and Bateman (1965). Plutons exposed along the eastern escarpment of the Sierra Nevada typically have U-Pb zircon ages between either 180-165 Ma or 96-88 Ma (Stern et al., 1981; Chen and Moore, 1982; Saleeby et al., 1990; Coleman et al., 1995; Coleman and Glazner, 1997). Both Jurassic and Cretaceous plutons are dominated by granodiorites with subordinate leucogranite. Cretaceous rocks also include an unusually high number of basaltic and dioritic rocks at this latitude (Moore, 1963; Frost and Mahood, 1987; Coleman et al., 1995; Sisson et al., 1996). Most Jurassic plutons are easily recognizable because they are cut by the 148 Ma Independence dike swarm which crops out nearly continuously between the central Sierra Nevada and the southern Mojave Desert (Moore and Hopson, 1961; James, 1989; Carl and Glazner, 2002). However, at least some such dikes in the region are Cretaceous (Coleman et al., 2000). Today's route takes us south down Owens Valley. Owens Valley is the westernmost basin of the Basin and Range, and for much of its length it separates predominantly plutonic rocks of the Sierra Nevada from predominantly sedimentary rocks of the White and Inyo Mountains. Geologic offsets indicate ∼65 km of right-lateral displacement across Owens Valley (Bartley et al., 2003; Kylander-Clark et al., 2005; Glazner et al., 2005). Driving south out of Bishop, a few miles south of town at M11 , the White Mountains to the east (left) are composed predominantly of late Proterozoic and early Paleozoic metasedimentary rocks. Black Mountain, the peak at 11 o'clock, contains a thick sequence of dark brown Campito Formation quartzite, which we will see trapped between plutons in the Sierra Nevada at the next stop. At M104 radio telescopes of the Owens Valley Radio Observatory are visible at 9 o'clock. Entering Big Pine, Birch Mountain is the dominant peak at 2:45, and Crater Mountain, a tall basalt cinder cone of the Pleistocene Big Pine volcanic field, is at 1 o'clock.

Abstract The Mississippian strata of Southern Alberta plains region, known only from the subsurface, are described as to lithology, thickness, rock units, their correlation with adjacent areas, and history of deposition. The Mississippian section thins from west to east due to post-Paleozoic erosion and to a lesser degree by reason of depositional thinning. In the extreme western part of the map area, there remains approximately 1,500 feet which is one third of the total Mississippian exposed in the mountains. The rock units and member names introduced and defined by Douglas in 1953 and the more recently amended subdivisions and new names being proposed by the Mississippian Committee for the foothills area in the vicinity of Turner Valley oil field are defined, for adjacent Plains region, in the Shell-Anglo Canadian Pine Creek well. The formation names, Bakken, Banff, Pekisko, Shunda, Turner Valley, and Mount Head, are used in this general area. It is further proposed to introduce the name Elkton for the commercial gas zone of the Great Plains, et al ., Elkton No. 16–13 well. This zone is regarded as the correlative of the “Crystalline” and “Lower Porous” zones of Turner Valley field usage. The correlation of these rock units is illustrated on cross sections from the Shell-Anglo Canadian Pine Creek well to the northeast, toward the Big Valley oil field, southeast to Saskatchewan, and south to Kevin-Sunburst area in Montana. The Banff strata of the Shell-Anglo Canadian Pine Creek well are correlated with the combined MC and MB2 (Lodgepole) of the Kevin-Sunburst area; the Pekisko and Shunda formations, plus Elkton member of Turner Valley formation, with MB1 (Mission Canyon) ; and the upper part of the Turner Valley with the MA unit as defined by Sloss and Laird (1945). The typical lithological units of the Bakken formation of Montana and the Dakotas are present in the southeastern part of the map area. Pre-Mississippian epeirogenic uplift has caused thinning of the Bakken formation to near zero toward the west. To the north, only the lower black shale is present as a distinguishable rock unit to which the name Exshaw is applicable. The upper part of the formation changes to gray shale which is not readily distinguished from the overlying Banff shale.

Recent geological mapping, geophysical studies, and deep drilling in the Raft River area, Idaho, have yielded information that is not consistent with fault-block development of the Raft River basin. Paleozoic and lower Mesozoic allochthonous rocks that occur in the surrounding Sublett, Black Pine, Albion, and Raft River Mountains do not occur beneath the Cenozoic basin fill deposits of the Raft River Valley, nor do Cenozoic volcanic rocks that form the adjacent Cotterel and Jim Sage Mountains. Range-front faults have not been identified along the margins of ranges flanking the Raft River Valley. Normal faults found in the Cotterel and Jim Sage Mountains are inferred to be concave-upward extensional structures that involve only Tertiary volcanic rocks and basin-filling sediments. Concave-upward faults within the Raft River basin have been identified in seismic reflection profiles. Fault displacement of the basement rocks beneath the Raft River Valley has not been documented. Structural development of the Raft River basin based on gravity-induced tectonic denudation of nearby metamorphic core complexes is suggested.

Abstract For the last several decades, gold exploration in Nevada has been strongly focused on sedimentary rock-hosted gold deposits in the Carlin, Cortez, Independence, and Getchell trends in north-central Nevada. Accordingly, less exploration activity has been directed toward the search for similar gold deposits in the eastern Great Basin, south and east of the major trends. Deposits in the central and northern Carlin and Cortez trends are hosted primarily in Upper Devonian middle slope soft-sediment slumps and slides and base-of-slope carbonate debris flows, turbidites, and enclosing in situ fractured lime mudstones. This is in marked contrast to gold deposits in the eastern Great Basin that are hosted primarily in three chronostratigraphic horizons: (1) shallow-water, Cambrian and Ordovician carbonate platform interior, supratidal karsted horizons and shelf lagoon strata, associated with eustatic sea-level lowstands and superjacent, transgressive calcareous shale and siltstone horizons that are deposited as sea level begins to rise, (2) Early Mississippian foreland basin turbidites and debris flows overlying karsted Late Devonian platform strata, and (3) Pennsylvanian and Permian shallow marine basin strata. Stratigraphic architecture in these three horizons was influenced in part by Mesozoic (Elko and Sevier) contractional deformation, including low-angle thrust and attenuation faults, boudinage, and large-scale folds, which in turn affected the orientation and localization of synmineral brittle normal faults. A compilation of past production, reserves, and resources (including historic and inferred) suggests an overall endowment of over 41 Moz of gold (1,275 tonnes) discovered to date in the eastern Great Basin, some in relatively large deposits. Significant clusters of deposits include the Rain-Emigrant-Railroad and Bald Mountain-Alligator Ridge areas on the southern extension of the Carlin trend, the Ruby Hill-Windfall-South Lookout-Pan on the southern extension of the Cortez trend, and the Long Canyon-West Pequop-Kinsley Mountain area near Wells, Nevada. Sedimentary rock-hosted gold deposits extend to the eastern edge of the Great Basin in Utah and Idaho and include the past-producing Black Pine, Barney’s Canyon, Mercur, and Goldstrike mines. The recognition of widespread, favorable host rocks and depositional environments on the Paleozoic platform-interior shelf in the eastern Great Basin opens up vast areas that have been relatively underexplored in the past. A basic premise throughout this paper is that the better we understand the origin of rocks and the depositional and postdepositional processes under which they formed, the more accurately we can make well-founded stratigraphic, sedimentological, structural, geochemical, and diagenetic interpretations. Without this understanding, as well as the rigorous application of multiple working hypotheses to explain our observations, the advance of science and the discovery of gold deposits is problematic.

ABSTRACT The northern Rocky Mountain Trench of eastern British Columbia is a broad valley mantled by glaciolacustrine terraces supporting a complex mix of mesic-temperate (“interior wet belt”) forests that are strongly affected by terrain and substrate. Neither the geomorphic history during early Holocene deglaciation nor the vegetation history of the origin of the Tsuga heterophylla (western hemlock) and Thuja plicata (western redcedar) populations in the interior wet-belt forest is well understood. Sediment cores were obtained from two lakes, 10 km apart and occupying different terraces (83 m elevational difference), and these were compared to existing fire-history and paleoclimate reconstructions. Radiocarbon dates and a mapped terrain classification indicate the upper terrace formed as a lacustrine and glaciofluvial kame terrace hundreds of years prior to the lower terrace, which was formed by glaciolacustrine sediments of a proglacial lake. The minimum limiting ages of these terraces correlate with dated jökulhlaup deposits of the Fraser River. The upper site’s first detectable pollen at >11.0 ka was dominated by light-seeded pioneer taxa (Poaceae [grasses], Artemisia [sagebrush], and Populus [aspen]) followed by a peak in Pinus (pine) and finally dominance by Betula (birch) at 10.2 ka. Pollen data suggest an earlier invasion of T. heterophylla (western hemlock) (by ca. 8 ka) than previously understood. Wetlands on extensive, poorly drained, glaciolacustrine soils promoted the persistence of boreal taxa and open forests (e.g., Picea mariana [black spruce]), while the better-drained upper kame terrace promoted development of closed-canopy shade-tolerant taxa. Invasion and expansion of mesic cedar-hemlock taxa progressed since at least the middle Holocene but was highly constrained by edaphic controls.