Abstract:
The internal stratigraphy of the Cutoff Formation in the Guadalupe Mountains is clarified, and the unit is divided into three members: the Shumard Canyon, the El Centro, and the Williams Ranch members. The Shumard Canyon Member of the Cutoff Formation in the Guadalupe Mountains correlates to the upper part of the Cathedral Mountain Formation in the Glass Mountains. The El Centro and Williams Ranch members of the Cutoff Formation and the lower part of the Brushy Canyon Formation, including the Pipeline Shale in the Guadalupe Mountains, correlate to the Road Canyon Formation. The changeover in conodonts from transitional forms to Mesogondolella nankingensis) provides a basal definition for the Guadalupian and occurs within correlation unit 3 in the El Centro Member of the Cutoff Formation and cycle 2 of the Road Canyon Formation.
The geology, stratigraphy, and depositional setting of the Permian in the Del Norte Mountains and of the Word Formation in the Glass Mountains are discussed in detail, and this data suggest deposition in a foreland basin or backbay between the Marathon Fold Belt and the Delaware basin. The internal stratigraphy of the Road Canyon, Word, Vidrio, Altuda, Capitan, and Tessey formations reveal the following: (1) the Road Canyon was deposited in four cycles and the Word in six cycles; (2) the Altuda can be divided into five informal members and the Tessey into three members; (3) the Vidrio is an unconformity-bounded unit; and (4) the Capitan displays characteristic platform margin to slope foresets.
Biozonation of the Guadalupian is discussed, and details are provided on the fusulinid and conodont zonations. Changes in conodont fauna, based on the succession of Mesogondolella species from M. nankingensis to M. altudaensis, divide the Guadalupian into five zones.
Five new species of conodonts (Sweetina crofti Wardlaw, Mesogondolella shannoni Wardlaw, Hindeodus wordensis Wardlaw, Iranognathus punctatus Wardlaw, and Sweetognathus bicarinum Wardlaw) and two new species of fusulinids (Codonofusiella (Lantschichites) altudaensis Wilde and Rudine and Rauserella bengeensis Wilde and Rudine) are described.
