New Mexico Geological Society Annual Spring Meeting — Abstracts

Lacustrine and fluvial sediments thought to be outliers of the Moenkopi Formation in the Lucero Mesa area of Valencia County, New Mexico were sampled for microfossils. These samples yielded charophytes and ostracodes. The charophytes are represented by two species of Porochara and one of (?) Altochara. The ostracodes are represented by two species of Darwinula, one species of Darwinuloides, and one species of (?) Gerdalia. The fauna and flora are most abundant in the middle and upper parts of the basal lacustrine unit. The red overbank mudstones overlying this yellowish laminated shale contain rare, poorly preserved specimens of (?) Darwinula.

Darwinuloides is apparently restricted to Lower Triassic units in the Soviet Union and the Lower Triassic Bundsandstein of Germany. The presence of this genus in the basal Moenkopi samples suggests an Early Triassic age for the basal Moenkopi in the Lucero Mesa region. The charophytes and ostracodes further suggest a clear, highly mineralized lacustrine environment of less then nine meters depth in the section sampled.