INTEGRATED BIOSTRATIGRAPHY OF CONODONTS, FORAMINIFERS AND RADIOLARIANS FROM THE UPPERMOST GUADALUPIAN (MIDDLE PERMIAN) IN THE APACHE MOUNTAINS, WEST TEXAS

A continuous section in the Apache Mountains of West Texas containing an uppermost Bell Canyon (Guadalupian) stratigraphic succession and overlain by the Castile Formation (Lopingian, Upper Permian) was recently described in Lambert et al. (2002). Additional study of this section has revealed that biostratigraphically equivalent strata to the upper part of the Lamar and Reef Trail members (as defined in the Guadalupe Mountains) are present. The upper part of the Lamar equivalent strata contains the late Middle Permian fusulinacean Paradoxiella pratti, and the Reef Trail equivalent contains Paraboultonia splendens. A thick debris flow between these two intervals contains the fusulinaceans Codonofusiella extensa, Yabeina texana, Reichelina lamarensis, and fragments of Polydiexodina. Small foraminifers are represented by the calcareous species Pseudohemigordius incredibilis throughout the succession, and the agglutinated Reophax and Ammobaculites-type forms in the lower part of the Reef Trail equivalent. Some of these species of fusulinaceans and small foraminifers are known in the Tansill Formation of Dark Canyon in the Guadalupe Mountains. The conodonts Jinogondolella postserrata and J. shannoni are present in the Lamar equivalent beds. In the Reef Trail equivalent the conodont succession is Jinogondolella altudaensis, J. crofti, transitional forms from J. altudaensis to Clarkina postbitteri hongshuiensis, and C. postbitteri hongshuiensis. The latter subspecies occurs at the top of the Reef Trail equivalent succession immediately below the basal part of the Castile Formation and is the marker for the terminal Guadalupian at the Lopingian GSSP in China. Radiolarians present at several levels in this succession include Follicucullus scholasticus and Pseudoalbaillella aff. P. fusiformis in the Lamar and Reef Trail equivalents, and Grandetortura aff. G. nipponica, Cauletella manica, Follicucullus charveti, F. orthogonus, and Albaillella yamakitai in the Reef Trail. The latter species has been proposed as a marker for the Guadalupian/Lopingian boundary based on radiolarians, but occurs below this boundary in the Apaches as based on conodonts that define the boundary.