Abstract A complete section of the Fort Hays Limestone Member occurs within roadcuts along Kansas 24, 2.4 mi (3.8 km) west of Stockton (Stockton 7½-minute Quadrangle) in NE¼Sec.21, T.7S., R.18W., Rooks County, Kansas (Fig. 1). At this locality, a series of three roadcuts occurs within a 0.25-mi (0.4 km) stretch of highway. Stratigraphically higher beds of the Fort Hays crop out at the east end of the exposures. By utilizing all three outcrops, most beds of the unit can be examined near road level with a minimum of climbing.

Abstract: The Permian Basin of West Texas and southern New Mexico is located in the foreland of the Marathon-Ouachita orogenic belt. This complex foreland area consists of several sub-basins that are separated by intraforeland uplifts. This study examined the tectonic, kinematic, and subsidence history of the Permian Basin in order to evaluate how intraforeland deformation affected stratigraphic development. We focused on: (1) the kinematic history of the Central Basin Platform (CBP), an intraforeland uplift that trends at high angles to the frontal thrust of the Marathons and separates the Delaware and Midland Basins; and (2) subsidence and stratigraphic analyses of the Midland, Delaware, and Val Verde Basins. Structure contour maps, seismic profiles, and balanced structural cross sections show that the CBP can be subdivided into two fault-bounded "blucks," the Fort Stockton and Andector Blocks, which are arranged in a left-stepping, en echelon pattern. The distribution of structural features associated with the CBP is best explained by clockwise rotation of these blocks plus an additional component of east-west compression. The rotation model explains: (1) the steeply dipping reverse faults at the SW and NE corners and local extensional faults at NW corners of individual crustal blocks that comprise the CBP; (2) the large structural relief observed at the SW and NE corners of individual blocks; and (3) decreasing amounts of basement shortening away from thrust-faulted corners that can be documented along both sides of the Fort Stockton Block. An additional component of shortening is required to account for imbalances between the amount of shortening versus extension observed along block boundaries. Subsidence analyses from several points in the Midland, Delaware, and Val Verde Basins indicate that the main phase of tectonic activity probably began during middle Pennsylvanian time. Rapid subsidence in each basin began at that time and continued until Early Permian time. Thereafter, subsidence slowed considerably to the end of the Permian. Late Paleozoic unconformities developed across the CBP and locally in adjacent basinal areas at the same time as rapid subsidence in the basins, suggesting that they are related to the same general episode of tectonic activity. Upper Pennsylvanian to Lower Permian stratigraphic cross sections show that synorogenic strata generally thicken toward the CBP. These stratal relationships indicate (hat the CBP acted as an intraforeland load that caused flexure of the adjacent sub-basins that comprise the Permian Basin. The thickest accumulation of upper Pennsylvanian to Lower Permian strata is developed next to the SW and NE corners of the Fort Stockton and Andector Blocks, which also corresponds to the areas where block uplift was greatest. Finally, the variable platform-to-basin relief that was produced during uplift of the CBP resulted in very different patterns of stratigraphic onlap during late Pennsylvanian to Early Permian time. Onlapping upper Pennsylvanian to Wolfcampian strata extend farthest across the top of the CBP where structural relief was least (i.e., at (he NW and SE block corners). Stratal onlap is minimal at (he SW and NE block corners because structural relief was greatest there. This study illustrates how patterns of intraforeland deformation can dramatically affect basin stratigraphy during synorogenic stages of basin development.

Abstract Uppermost Aptian-Albian-lower Cenomanian strata of the Texas Comanchean Series represent three long-term transgressive-regressive cycles: the Trinity, Fredericksburg, and Washita groups that are composed mainly of marine limestone and shale. Each group is composed of shorter term deepening-shallowing cycles. On the Central Texas San Marcos Platform and its downdip equivalents, subsurface strata above the Trinity Group are grouped into the Edwards and Washita groups. Correlations in the 1960s were based on wireline well logs and inferred biostratigraphy that correlated the upper Edwards Group Person Formation with the lower parts of the Washita Group. This correlation crosses a widespread subaerial unconformity that separates the Washita from the underlying Fredericksburg in the northern East Texas Basin and in the Fort Stockton Basin. New biostratigraphic and sedimento-logical data show that the Person actually correlates with the upper part of the Fredericksburg in the Gulf Coast.

Abstract Known commercial deposits of native sulfur in West Texas are restricted to bedded sulfate evaporites of the western Delaware Basin (Rustler Springs sulfur district of Culberson and Reeves Counties) and the southern Central Basin Platform (Fort Stockton sulfur district of northern Pecos County) (Fig. 1). In both these regions Upper Permian (Ochoan) evaporite strata host locally voluminous but notoriously unpredictable, sporadic deposits of biogenic native sulfur. This paper summarizes the processes and conditions of biogenic sulfur formation, describes the distribution and structural setting of sulfur in the Rustler Springs sulfur district, and presents some ideas concerning potential exploration strategies for these elusive deposits.

Abstract The Pennzoil Sulphur Company's Culberson mine near Orla, Texas, remains the free world's largest producer of native sulfur by the Frasch method. Mining operations commenced on September 30, 1969, under the Duval Corporation, Pennzoil's mining subsidiary at that time. Total production from the Culberson mine is 37.7 million long tons (LT) through October 1, 1990. Production continues at a rate of about 1.9 million LT per year except for the past two years when production was reduced due to sof T market conditions. On June 9, 1985, a production record was set when 8,552 LT of molten sulfur were tallied for that day. Throughout most of 1985 the mine ran at the full operating capacity of 2.5 million LT per year. Geologic reserves were originally estimated to be about 81.5 million LT, with subsequent drilling data supporting this estimate. The mine site is spread over an area of 1,773 acres; the stratiform mineralized zone lies at a depth of 350ft to 600ft. Culberson's remaining reserves will allow it to produce into the 21st century. Pennzoil Sulphur was the first company to operate a Frasch-process sulfur mine in west Texas at its Fort Stockton property in Pecos County. The stratiform, evaporite-hosted sulfur deposits of this region are notorious among industry geologists and engineers for production problems related to highly fractured overburden and complex orebody geometries. Experience in mining these deposits has allowed Pennzoil to take advantage in careful mine planning and advanced production techniques to insure a level of efficiency required

Abstract A hydrodynamic study of several stratigraphic unitsin the Permian Basin shows a regional west-toeast dip of the potentiometric surface. The potentiometric surfaces of the Ellenburger and Devonian have both closed lows and closed highs against faults on the Central Basin platform, and that of the Ellenburger is low around the Fort Stockton uplift. Data for the Devonian showa steeper dip of the potentiometric surface in New Mexico than in Texas. The Mississippian data are too sparse to show significant features other than dip to the north, east, and south from Terry County, Texas. The Strawn potentiometric surface has steeper east dip on the east flank of the Midland basin, and approaches hydrostatic conditions around the Central Basin platform. The dip of the potentiometric surface of the Wolfcamp is to the east and north in New Mexico, and east and northeast in Texas. The San Andres shows east dip. The Delaware Mountain group has general east dip, but anomalous conditions are suggested in central Reeves County. The potentiometric surfaces of all units mapped have some common regional characteristics in spite of the wide differences in elevation and location of the outcrops and subcrops. However, locally, there are many variations. Tilting of the hydrocarbon accumulations is a significant factor in a few fields, but much apparent tilting is caused by discontinuous porous lenses and by low permeability. Vertical and horizontal pressure relationships around faults and subcrops, vertical and horizontal continuity of oil, relative permeability to oil, and other hydrodynamic conditions can be critical factors to be considered in exploration in the Permian Basin. Salinity maps of the Basin waters show a northwest-southeast trend of high salinity through the southeast corner of New Mexico. It is separated from a parallel high trend to the north, by a low trend with less than 50,000 ppm total solids. The quality of drillstem-test instrumentation and programming in the Permian Basin needs to be improved to furnish the pressure data that should be available to the industry.