During the past 15 yr, the global requirement for fertilizers has grown considerably, mainly due to demand by a larger and wealthier world population for more and higher-quality food. The demand and price for potash as a primary fertilizer ingredient have increased in tandem, because of the necessity to increase the quantity and quality of food production on the decreasing amount of available arable land. The primary sources of potash are evaporites, which occur mainly in marine salt basins and a few brine-bearing continental basins. World potash resources are large, but distribution is inequitable and not presently developed in countries where population and food requirements are large and increasing. There is no known substitute for potash in fertilizer, so knowledge of the world’s potash resources is critical for a sustainable future. The U.S. Geological Survey recently completed a global assessment of evaporite-hosted potash resources, which included a geographic information system–based inventory of known potash resources. This assessment included permissive areas or tracts for undiscovered resources at a scale of 1:1,000,000. Assessments of undiscovered potash resources were conducted for a number of the world’s evaporite-hosted potash basins. The data collected provide a major advance in our knowledge of global potash resources that did not exist prior to this study. The two databases include: (1) potash deposits and occurrences, and (2) potash tracts (basins that contain these deposits and occurrences and potentially undiscovered potash deposits). Data available include geology, mineralogy, grade, tonnage, depth, thickness, areal extent, and structure, as well as numerous pertinent references.

The Bisoni-McKay area, a structurally isolated, fault-bounded horst, offset eastward at the south end of the Fish Creek Range, displays a geologic terrane that is previously unrecorded in Nevada, and perhaps elsewhere in North America. This unique terrane is an olistostrome that was shed eastward by listric faulting from the east side of the migrating Antler orogenic forebulge in Late Devonian (early Famennian, ca. 373 Ma) time. Stratigraphic identification of Devonian olistoliths and enclosing matrix that constitute the olistostrome, as well as overlying postemplacement units, is supported by correlation to formations in the main part of the Fish Creek Range and to the northwest in the northern Antelope Range. Precise zonal dating of map units and revised dating of Antler orogenic events are provided by 38 conodont collections recorded in the Devonian/Carboniferous (D/C) Conodont Database and by small collections of conodonts embedded in siltstone and mudstone. Our revision of regional geologic history uses Devonian conodont zones to measure “deep time” to circa millions of years before present. The upper Upper Devonian (Famennian) tongue of the Woodruff Formation was deposited directly on the olistostrome and is overlain by clastic Mississippian synorogenic deposits. These deposits were shed eastward from the evolving Antler highland and related Roberts Mountains allochthon into the Antler foredeep. We propose the following revised dates for important Devonian tectonic events in Nevada: initiation of Antler orogeny, ca. 385 Ma; downwarping of Pilot backbulge basin, ca. 382 Ma; initial uplift of the Antler highland, ca. 373 Ma; third, major pulse of highland uplift, ca. 364 Ma. A summation of regional geologic history indicates that the elapsed time from start of Antler orogeny to start of Roberts Mountains thrusting was ~30 m.y.

The 45 km 2 map area is situated at the south end of the Hot Creek Range in central Nevada, ~16 km east of the buried leading edge of the Mississippian Roberts Mountains thrust. Three eastward-trending left-slip faults divide the area into four structural blocks. The southernmost block is occupied solely by upper Oligocene volcanic rocks. The narrow northernmost block, now occupied surficially by valley fill and volcanic rocks, represents the south end of the main part of the Hot Creek Range, from which the study area is offset. The middle two blocks display different aspects of the eastward-traveled outer crater rim created by the ca. 382 Ma (early Late Devonian, middle Frasnian) Alamo impact. The Alamo impact was produced by a 5-km-diameter bolide, most likely a comet, which excavated a transient submarine crater 44–65 km in diameter. Comparison of thin (8–12 m) Alamo Breccia deposits in the northern of the middle two blocks with a more easterly, thick (35–42 m) Alamo deposit in the main Hot Creek Range, 4 km north of the map area, suggests that these blocks traveled many kilometers eastward. The northern of the middle two blocks contains a large olistolith capped by the thin breccia, whereas the southern block contains a larger olistolith lacking an Alamo Breccia cap. Three Devonian pulses of the Antler orogeny are better documented in the chapter on the Bisoni-McKay area. Here, the first Antler pulse in latest Middle Devonian time is obscured within an ~9 m.y. hiatus enlarged by excavation of the Alamo impact crater. The second Antler pulse is recorded by the ~4 m.y. hiatus produced by the regional unconformity between the lower and upper members of the Woodruff Formation. The third Antler pulse is documented by an ~8 m.y. regional hiatus between the Mississippian Webb Formation and Upper Devonian Woodruff Formation. In previous papers, we had interpreted this pulse to initiate the Antler orogeny.

Convergent orogenic systems pose challenges for the prospector seeking to predict oil and gas reservoirs, as these regions are often data poor. Explorationists, therefore, must often rely on conceptual models to predict the occurrence of oil and gas, and to choose the most favorable exploration areas. This paper examines how different conceptual models of hinterland evolution can influence predictions of hydrocarbon systems in an adjacent foreland. A one-dimensional (1-D) method was developed for assessing incremental hydrocarbon yield during progressive fold-belt deformation and source rock burial and maturation. This method was employed to evaluate the way in which hydrocarbon yield is affected by two different scenarios for the timing of uplift of the Puna Plateau and subsequent burial of the adjacent Metán region of northwestern Argentina. In the first scenario, plateau growth and burial of the Metán region begin in the early Miocene and progress to the present day. In the second scenario, plateau growth and basin formation occur predominantly in the Eocene, with minor deformation from middle Miocene to present. The later load timing decreases the relative volume of liquid hydrocarbons available to fill structural traps. The differences in charge volume and timing between the two scenarios are enhanced in this region as a result of thinned crust and relatively high heat flow that linger from a Cretaceous rifting event. The results of the study provide an example of how boundary conditions obtained from studies of an orogenic hinterland can be used to calculate risk for exploring a potential play within a basin where data are incomplete or inconclusive. They also yield general insights on the use of regional genetic concepts to predict thermal history and source rock maturation and yield in data-poor areas.