Abstract

The Hueco Group (Lower Permian, Wolfcampian) platform to basin carbonate succession exposed in the Hueco Mountains (western Diablo Platform) comprises a complex record of deposition controlled by changes in glacioeustatic sea level. The Hueco Group overlies the regional Powwow unconformity and, according to fusulinid biostratigraphy, correlates to the Nealian and Lenoxian substages of the Wolfcampian stratotype in the Glass Mountains. The succession consists of six composite sequences (W-1 to W-6) containing basin-to-slope to shallow platform facies. The shelf margins of composite sequences W-1 through W-4 are very well exposed in outliers west of the main escarpment. Composite sequences W-5 and W-6 are poorly exposed in isolated outcrops and the stratigraphy is poorly known. Composite sequences W-1 through W-4, and W-5 through W-6, form two stacked deepening followed by shallowing upward successions. Through W-1/-5, the shelf margin evolved from high-energy shoal to phylloid algal buildup. In the basin, resedimented carbonates are common and occur both below and above sequence boundaries. Highstand shedding was common during times of rapid progradation. Basinward restricted breccias and allodapic limestones overlie the sequence boundaries and margin collapse scars. The breccia characteristics suggest some were the product of highstand shelf margin erosion, but others are lowstand and transgressive deposits. The outcrop-based sequence stratigraphic model demonstrates the high degree of sub-seismic scale stratigraphic and facies complexity of Wolfcampian ice-house carbonate successions.