Calcareous microfossils from the Moenkopi Formation (Triassic, Scythian or Anisian) of central New Mexico
Kenneth K. Kietzke
Lacustrine and fluvial sediments of the Moenkopi Formation in the Lucero Mesa area of Cibola County, New Mexico yield charophytes, spirorbid worms and ostracods. Charophytes are represented by two species of Porochara and one of ?Altochara. The spirorbid is an uncoiled species of Spirorbis. The ostracods are represented by two species of Darwinula, two 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 of the Moenkopi. The middle of the red mudstone unit above this basal unit contains common-to-rare, fluvio-lacustrine microfossils.
Triassic Darwinuloides are apparently restricted to Lower Triassic units in the Soviet Union and to the Middle Triassic Buntsandstein of Germany. The presence of this genus in the basal Moenkopi samples suggests an Early to Middle Triassic age for the basal Moenkopi in the Lacero Mesa region. The Moenkopi spirorbid resembles Spirorbis aberrans (Hohenstein, 1913), a species from the Middle Triassic of Germany. The charophytes and ostracods suggest a clear but brackish water environment of less than 9 m depth in the lower part of the section sampled.
- Kietzke, Kenneth K., 1989, Calcareous microfossils from the Moenkopi Formation (Triassic, Scythian or Anisian) of central New Mexico, in: Southeastern Colorado Plateau, Anderson, Orin J.; Lucas, Spencer G.; Love, David W.; Cather, Steven M., New Mexico Geological Society, Guidebook, 40th Field Conference, pp. 181-190.