FUSULINID AND CONODONT ANALYSIS OF AN ATYPICAL CARBONATE-DOMINATED SECTION IN THE DELAWARE MOUNTAIN GROUP, PATTERSON HILLS, GUADALUPE MOUNTAINS NATIONAL PARK

The Patterson Hills lie in the southernmost portion of Guadalupe Mountains National Park, situated along the Texas-New Mexico border. This area has received little geologic research attention since the initial mapping by P. B. King (1948) in comparison to the main range of the Guadalupe and Delaware Mountains. Mapping and correlation in this area is complicated by extensive normal faulting and intense diagenetic alteration in places.

Back Ridge is of particular interest because it represents a predominantly carbonate section of the otherwise siliciclastic-dominated Delaware Mountain Group. The stratigraphic succession there ranges from upper Cherry Canyon Formation (South Wells Member) to the middle Bell Canyon Formation (Rader Member). The carbonates become less argillaceous and better exposed moving upsection. Fusulinids and conodonts from Back Ridge were studied to create a biostratigraphic column for comparison to more typical sections of the Delaware Mountain Group.

Fusulinids: Polydiexodina was recovered from the Pinery and Rader members. Other large fusulinids are rare; they occur mostly in the Pinery, which had the most abundant and diverse fauna in the section. Among the smaller fusulinids, Leella was noted in the Hegler, and Reichelina-like forms in the Rader. No fusulinids were recovered from the South Wells or Manzanita members, which are poorly exposed.

Conodonts: Jinogondolella aserrata was recovered from all members ranging from the South Wells to the lower Pinery. Jinogondolella postserrata ranged through the remaining Pinery and Rader. Other Jinogondolella recovered include J. palmata (South Wells through lower Pinery), J. errata (Pinery), and J. gladirobusta (Rader—and possibly uppermost Pinery). Pseudohindeodus ramovsi sensu lato was also recovered through the entire section.

These biostratigraphic results compare favorably with previously published descriptions for members of the Delaware Mountain Group. It supports the lithostratigraphic assignment of the members in this atypical carbonate-dominated area, and shows how often-overlooked parts of a national park can be significant for scientific research.