New Mexico Geological Society Annual Spring Meeting — Abstracts

Two palynomorph assemblages were recovered from the Paleocene Nacimiento Fm. (Tn), San Juan Basin, New Mexico in Kimbeto Arroyo. The first sample (SJB03-17) is from a carbonaceous mudstone ~1 m below strata of the Puercan (Pu2) NALMA and in a zone of normal magnetic polarity correlated with polarity subchron C29n. It yielded an assemblage including Arecipites sp., Corollina sp., Laevigatosporites sp., Momipites tenuipolus, Nyssapollenites spp., Pityosporites sp., Tricolpites anguloluminosus, Tricolpites spp., and Ulmipollenites krempii. The second sample (SJB03-19) is from a carbonaceous mudstone about 2 m above strata that yield a basal Torrejonian (To1) NALMA vertebrate fauna and within a succeeding zone of normal magnetic polarity correlated with polarity subchron C28n. It yielded an assemblage including Cicatricosisporites sp., Corollina sp. [common], Laevigatosporites sp., Momipites triorbicularis [common], Pityosporites spp., Tricolpites anguloluminosus, Ulmipollenites krempii, and Zlivisporis novomexicanum.

SJB03-17 contains Momipites tenuipolus, a taxon that is widespread in the lower Paleocene in the Western Interior. Its occurrence in this sample in the Tn is consistent with its known stratigraphic range. SJB03-19 yields Momipites triorbicularis, a taxon that indicates a correlation with Paleocene palynostratigraphic Zone P3 (the Momipites actinus-Aquilapollenites spinulosus Interval Biozone), a zone identified throughout the lower Paleocene of the Western Interior. The identification of Zone P3 in the Tn closely associated with a To1 vertebrate assemblage firmly establishes a correlation between the Paleocene palynostratigraphic and vertebrate biostratigraphic zonation of the Tn and provides an important biochronologic correlation for the Western Interior.