Lower Permian terrestrial Paleoclimatic indicators in New Mexico and their comparison to paleoclimate models
Greg H. Mack

Abstract:

 During Early Permian time, most of New Mexico occupied a position within ten degrees north of the equator in western Pangea. Wolfcampian paleoclimatic indicators, including paleosols, vertebrate fossils, plant fossils, and fluvial-channel architecture, suggest a warm, semi-arid to sub-humid paleoclimate characterized by seasonal precipitation. In contrast, widespread eolian sedimentation by northeasterly winds and evaporite precipitation during deposition of the Leonardian Yeso and Glorieta formations point to a more arid paleoclimate. Most numerical paleoclimatic models support the overall warm, seasonally dry paleoclimate, although some models predict greater precipitation in western equatorial Pangea than is indicated in the rocks.

The dry paleoclimate in western equatorial Pangea probably resulted from the breakdown in zonal circulation due to the large size of Pangea, as well as an orographic effect of the ancestral Rocky Mountains, although the latter is not viable during Leonardian time when the mountains in New Mexico were eroded and onlapped. The increase in aridity from Wolfcampian to Leonardian time may have been influenced by the northward shift of Pangea, melting of continental glaciers in Gondwana, and/or a greenhouse effect due to increasing concentration of carbon dioxide in the atmosphere. 


Citation:

  1. Mack, Greg H., 2003, Lower Permian terrestrial Paleoclimatic indicators in New Mexico and their comparison to paleoclimate models, in: Geology of the Zuni Plateau, Lucas, Spencer G.; Semken, Steven C.; Berglof, William R.; Ulmer-Scholle, Dana S., New Mexico Geological Society, Guidebook, 54th Field Conference, pp. 231-240.

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