Geology and mineralization of the Culberson sulfur deposit

—The Culberson sulfur deposit occurs as a replacement of Upper Permian evaporites (Salado and Castile Formations) by sulfur-bearing carbonates in the west-central Delaware basin. Structures derived from two major periods of tectonic activity control the location of sulfur mineralization. Pre-mineralization faults developed in response to Laramide compressional tectonics in the Late Cretaceous to early Tertiary, as indicated by breccia clast assemblages filling paleokarst features along the faults. Basin and Range extensional tectonics uplifted the western Delaware basin beginning in the middle to latest Miocene, resulting in a change in basin hydrodynamics conducive to bioepigenesis. Age of mineralization may be less than 5 Ma, based on mineralization crosscutting karst-related deposits thought to be of Ogallala (middle-late Miocene) age. Crude oil analyses and con - elation of anionic ground water constituents indicate the Guadalupian Cherry Canyon Formation is a probable source for hydrocarbons and oxygenated waters necessary for bioepigenetic sulfur deposition at Culberson. Sulfur occurs as microcrystalline disseminations in replacement limestone and as crystalline vug fillings associated with epigenetic barite, celestite and isotopically light carbonate minerals. The timing and kinematics of the Culberson and Phillips Ranch and Nestlerode, 1992) fault systems may be related to similar regional tectonic events, but locally different stress regimes, during the Late Cretaceous. The trend of these faults conforms to wrench fault tectonic features described by Bolden (1984) as part of a northwest- trending series of left-lateral faults that lie north of and subparallel to the Texas lineament. The locations of the Culberson and Phillips Ranch deposits are within a 6-mi-wide northwest-trending disturbed zone that Bolden named the Pecos lineament. According to Bolden (1984) and others, repeated movement along these faults occurred between the Mississippian and Tertiary. The fault trends identified at Culberson are parallel to a right-lateral conjugate shear stress regime within the disturbed zone. The fault trends at Phillips Ranch are compatible with a related tensional regime. A regional wrench fault mechanism is a possible explanation for the differences in the fault kinematics apparent at Phillips Ranch and Culberson, with the timing of fault development in general agreement with relative timing of breccia development along faults at Culberson. However, as noted above, horizontally slickensided surfaces may not be reliable indications of tectonic activity. The high- angle dips and local reversals of offset along the strike of the faults at Culberson suggest reverse faulting that was caused by a compressional regime. We recognize the possible existence of numerous normal faults that, based on limited borehole information, might suggest offset re- versal along a single fault. However, we believe that the faults originally formed in a compressional regime, as suggested by high angles of dip, that were later reactivated by extensional tectonism. Ba suggest influx of basinal waters (oil-field brines) admixed with fresh recharge waters in the Cherry Canyon. The influx of metalliferous brines carrying relatively high Sr values has been noted in other localities (Saunders, 1988) and explain anomalous quantities of celestite mineralization. Features derived from uplift during two major tectonic the controlling for mineralization at