ABSTRACT: The Fusselman Formation (Lower and Middle Silurian) of the Franklin Mountains of West Texas and South-Central New Mexico

LeMONE, DAVID V., University of Texas at El Paso, El Paso, TX

The Fusselman Formation of the Franklin Mountains is a massive, vuggy, finely to coarsely crystalline, whitish unit with 185 m stratotype in the north-central part of the range where it forms the main ridge. The formation has been subdivided into three members (in ascending order): Chamberino (80 m), Flag Hill (29 m), and Crazy Cat (76 m). The members may be broadly interpreted as a series of three shoaling-upward sequences with minor karsting reported at the contact between the Chamberino and the Flag Hill members. The formation is dolomitic with the exception of a few limestone ("Hi Cal") lenses in the Crazy Cat Member.

The formation rests disconformably on the karsted, low-relief surface of the underlying Cutter Formation of the Late Ordovician Montoya Group. The age of the Fusselman has been determined to be Early-Middle Silurian (Alexandrian-Niagaran) in the Franklins. The Fusselman is overlain by the upper Middle Devonian Canutillo Formation. The disconformity between the underlying uppermost Tippecanoe Fusselman and the overlying basal Kaskaskia Canutillo is on the order of 40 m.y. Extensive karsting developed on the top of the Crazy Cat Member and its equivalents on the Tobosa basin ramp during this time. This karsted terrain, where overlain by the proper seal and supplied by an adequate source bed, produces within the Permian basin.

AAPG Search and Discovery Article #91018©1992 AAPG Southwest Section Meeting, Midland, Texas, April 21-24, 1992 (2009)