REEVALUATION OF THE DEPOSITIONAL SETTING OF THE PERMIAN (GUADALUPIAN) GOAT SEEP LIMESTONE REEF, GUADALUPE MOUNTAINS NATIONAL PARK, TEXAS, USA

King (1948) named the Goat Seep Limestone from its exposure below Bush Mountain on the Western Escarpment of the Southern Guadalupe Mountains in west Texas, where the massive facies is about 185 meters thick, standing as “… a single massive bed of limestone, without trace of bedding planes.” The Goat Seep Limestone looses its massive nature shelfward and basinward as it thins and exhibits well-developed bedding with a number of interbedded sandstones. King noted genetic similarities between the massive facies of the Goat Seep and the overlying Capitan limestones, and interpreted both formations to be fossil reef systems. Newell et al. (1953), in their paleoecological analysis of the Permian Reef Complex, interpreted the Goat Seep to have been a near-continuous barrier reef that grew around the margin of the Delaware Basin in a manner similar to the younger Capitan Limestone reef. Neither King nor Newell et al. discussed the lithological composition of the Goat Seep massive facies.

Crawford (1981) examined the Goat Seep Limestone in Guadalupe Mountains National Park and the Lincoln National Forest (New Mexico) and decided that the “reef” facies was actually a bedded deposit composed of transported skeletal and non-skeletal carbonate grains. His measured sections indicated that the dominant lithologies were floatstones and rudstones, with subordinate interclastic breccias and volumetrically minor organic framestones, bafflestones, and bindstones. He concluded that the Goat Seep Limestone was not deposited in a reef setting.

Reexamination of the outcrops studied earlier by King, Newell et al., and Crawford indicates that dolomitization was more extensive in the younger Goat Seep. Where heavily dolomitized, all traces of depositional fabrics have been obliterated; however, where less extreme, sponge framestones, bafflestones, and bindstones are the dominant lithological fabrics. Crypt fabrics are present and resemble those of the Middle Capitan Limestone reef along the Permian Reef Geology Trail in McKittrick Canyon. Reexamination of massive facies outcrops failed to detect either clastic carbonate textures or bedding surfaces. By comparison with the Lower, Middle, and Upper Capitan Limestone reefs, we concur with King and Newell et al. that the Goat Seep Limestone represents a fossil reef system.