Abstract

Munn Formation outcrops adjacent to Munn Valley on the west side of the Apache Mountains bear a record of Guadalupian deposition that is unique to the Permian Basin for several reasons. First, the Apache Mountains formed an isolated platform, the Apache Platform. This platform was isolated to the north by the Diablo Channel, to the east by the Delaware Basin, to the south by Hovey Channel, and to the west by the Marfa Basin. Second, isolation of the Apache Platform explains why the lower Munn (Grayburg equivalent) contains no siliciclastic beds or sandy dolostones, and why there are only a few sandy dolostones upon and above the composite sequence boundary in the base of the upper Munn (Queen equivalent) that disappear further upsection. Third, the Munn was deposited on a distally steepening ramp, which contained at least six sets of prograding clinoforms within the lower Munn. Fourth, mound complexes were identified in the lower Munn. Mounds appear to be at a specific distance down ramp and may align in strike view. Fifth, sponges have been identified in the lower Munn. They appear to be Heliospongia, the same sponges that have been recently identified in Grayburg outcrops in the Guadalupe Mountains. Sixth, a down slope debris flow, composed of angular to rounded, cobble to grit size clasts that are set within a carbonate mud-rich matrix, has been identified.

Outcrops in the Apache Mountains may be similar to outcrops in the southern part of the Central Basin Platform and may serve as an outcrop analogue. Additional fieldwork will add more measured sections and connect existing sections much better in both dip and strike view.