253-8 Desmoinesian Conodonts of the southern Taos Trough region: Evidence from the San Jose 7.5’ Quadrangle, New Mexico

Session: Conodonts from North America and Beyond - Honoring the Career of Dr. James E. Barrick

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Abstract:

In the Taos Trough region, there is an accumulation of mixed carbonate and siliciclastic strata with complex lateral facies relationships. To the north, the dominantly carbonate Porvenir Formation contains Desmoinesian conodonts. To the south, the lithostratigraphic nomenclature transitions to the clastic Flechado Formation which is age constrained by brachiopods as Desmoinesian. The purpose of this study is to determine if there is a carbonate-rich unit of Desmoinesian age within the San Jose Quadrangle of New Mexico, and if so, can the Porvenir Formation, as a mappable unit, be extended to the south.

Conodonts including Neognathodus (post-colombiensis) and Idiognathodus rectus were recovered from the lower and upper intervals of a carbonate-rich unit in the San Jose Quadrangle. This unit is equivalent both lithologically and in age to the Porvenir unit to the north, and can be assigned to it. This interpretation is supported by upper Desmoinesian conodonts sampled from a clastic-rich unit above the carbonate-rich unit, which was recently mapped as Alamitos Fm. in the Taos Trough. The findings demonstrate that a widespread carbonate-rich Desmoinesian unit (Porvenir Fm.) extends into the siliciclastic dominant southern Taos Trough region. These results are also consistent with a carbonate interval of Desmoinesian age observed in other basins across much of New Mexico.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6394

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