... are similar to those of Hadrophycus immanis from the Nash Fork Formation of the Medicine Bow Mountains 200 km to the southwest, which is generally considered to be early Proterozoic in age. Stromatolites that are exposed in the upper part of the Whalen Group are small- and medium-sized stratiform, columnar...

... are thought to be shear zones of Precambrian age analogous to the Mullen Creek-Nash Fork shear zone of southeast Wyoming. Stratigraphic evidence suggests that the structural lineaments which form the Belle Fourche arch have rejuvenated periodically throughout the Phanerozoic. Subtle movements along...

... extension of the Mullen Creek-Nash Fork shear zone in Precambrian rocks of the Medicine Bow Mountains. North of this zone the dominant feature is the Rock River line of folding and the Cooper Lake depression. Cross sections of the anticlines reveal a systematic pattern of internal deformation...

... only after the formation of Yellowstone caldera. Our new 40 Ar/ 39 Ar data support frequent volcanic activity in Henrys Fork Caldera over the past 1.3 m.y., most notably prior to and following the eruption of the Lava Creek Tuff, in conjunction with rhyolitic volcanism in and around Yellowstone...

..., and Pb contents seem to reflect contributions from mafic volcanic sources ( Nash and Hahn, 1987 ; Nash, 1989b ). The absence of mineralization ages complicates the choice between genetic models for the Blackbird ores. Whole-rock samples of the Apple Creek Formation define a highly radiogenic common...

... dates from seventeen samples range from 7.9 ± 1.4 Ma to 55 ± 10 Ma. Most cooling dates from Cretaceous plutons adjacent to the WSRP are Eocene, while Eocene intrusions from within the Middle Fork Boise River canyon ~35 km NE of the WSRP yield Miocene cooling dates. The AHe dates provide evidence...

... 10 hrs.   Dundee   Mecosta Fork 16-16N-7W Smith Petroleum Co. Buss 1 10875 8-14 3,782 99   Dundee   Missaukee E. Norwich 16-24N-5W Sun Oil Co. Horner 14 10937 12-16 4,501 pb4,458 60   Detroit River   New Producing Formations Genesee Otisville 6-9N-8E Clyde L...

... and Christiansen (1985) . The Challis Volcanic Field in central Idaho ( Snider and Moye 1989 ), not shown, may have also have contributed ashes to the region. C, H, W, and HD refer to the Church Buttes, Henrys Fork, White Lignitic, and Halfway Draw tuffs, respectively. T able 1. Summary of 40 Ar/ 39...

... Yellowjacket Formation ( Tysdal and Desborough, 1997 ; Winston, 2007 ). In addition to the high K content of the brine, the high salinity and low Mg/Cl ( Table 3 ) are consistent with the formation of gangue biotite with high Cl and low Mg ( Nash and Connor, 1993 ). Such brine might also explain the K...

... of AMD occurred in 2015. This release resulted in the discharge of approximately 11 300 cubic metres of acidic and metal-rich water into North Fork Cement Creek, which ultimately was transported to the Animas River, San Juan River and Colorado River ( Rodriguez-Freire et al. 2016 ). Subsequent...

... of late Pleistocene Lake Bonneville. Analysis of facies architecture indicates that the Weber and Spanish Fork deltas were strongly wave-modified because they were situated along openly exposed portions of the shoreline. The Bear River delta, nestled in a relatively isolated northeast arm of the lake...

... membrane with microtrichia only; R 1 long, extended to level of or slightly past base of fork of R 2+3 -R 4+5. Point of Rs joining R 1 distal to point where Rs joins M. R 2+3 and R 4+5 apically branched, forking just beyond middle of the Rs vein; R 2+3 connecting to C close to R 1 . Sc vein reduced...

..., the host strata were included in the Mesoproterozoic Yellowjacket Formation ( Ross, 1925 ; Vhay, 1948 ; Lopez, 1981 ; Nash and Hahn, 1989 ; Evans and Connor, 1993 ) and correlated with the lower part of the Belt Supergroup, host to syngenetic Sullivan sedex Pb-Zn deposits ( Ruppel, 1975 ; Hahn...

... remnants of the overlying Jurassic Carmel Formation present in a single tributary that joins Lake Canyon downstream of the study area. The Navajo Sandstone in the field area is thickly cross-bedded, fine-grained, carbonate-cemented eolian sandstone that contains a few thin lenses of gray, cherty...

... cements indicate that methane was not the major source of carbon in their formation ( Wigley et al., 2012 ). At Egypt, Dry Fork, Buckskin Wash, Paria Canyon, and Three Lakes Canyon, many spheroidal calcite-cemented concretions are preferentially developed in the lower portions of grain-flow strata...

... and its relationships to post-Precambrian structural patterns (abs.) : Am. Assoc. Petroleum Geologists Bull. , v. 49, p. 115 . Houston , R. S. , and McCallum , M. E. , 1961 , Mullen Creek-Nash Fork shear zone, Medicine Bow Mountains, southeastern Wyoming (abs.) : Geol. Soc. America...

... and Goddard, 1950 ). Hills and Houston (1979) related a northeast-trending lineament in south-central Wyoming to the Mullen Creek/Nash Fork shear zone, which is interpreted as a through-going structure of major proportions (7 km or 4.35 mi wide and several hundred kilometers long). Thomas (1971...

... deposits homogenize in the range of 180° to 400°C ( Nash, 1976 ). Fluid inclusion estimates for formation of phyllic veins range from 200° to 350°C at Santa Rita, New Mexico ( Reynolds and Beane, 1985 ), and are 300°C in phyllic veins in the Mineral Park porphyry deposit, and 300°C at Sierrita ( Bean...

... with source beds, seals, and reservoir lithology. Under “Total Petroleum System-System Name,” green indicates oil-prone Sys. and pink indicates gas-prone Sys. Barbed circle indicates the formation is an oil and gas producer. CO = Colorado; Fm. = Formation; KS = Kansas; L. = Lower; M. = Middle; OK = Oklahoma...

... deposit were found: Smithson (2004 ; North Fork porphyry Cu-Au deposit, Washington, USA), Klemm et al. (2007 ; El Teniente porphyry Cu-Mo deposit, Chile), Klemm et al. (2008 ; Questa porphyry Mo deposit, New Mexico, USA), Armstrong (2012 ; Batu Hijau porphyry Cu-Au deposit, Indonesia), Seo et al...