2 Permian of the South-Central U.S.: Land and Sea

Monday, 9 March 2020
8:00 AM - 12:00 PM
Meeting Room 202CD

THE PERMIAN WORLD: PLATE TECTONICS, PALEOGEOGRAPHY, PALEOCLIMATE, & PALEOBIOGEOGRAPHY

Paper number: 2-3
Program: Theme Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

To tell the story of the Permian, we present 34 plate tectonic, paleogeographic, paleoclimatic, and paleobiogeographic reconstructions. Several animations will also be shown that illustrate the dynamic nature of Permian tectonics, geography & climate. The Permian began in an extreme ice house world and ended in an extreme hot house world that wiped out 99.9% of all life on Earth. The Permo-Triassic Extinction was caused by the eruption of the massive West Siberian LIP. During the earliest Permian, ice and snow covered nearly all of Gondwana. These frigid conditions gradually ameliorated and virtually all of the ice was gone by the late Artinskian (285 Ma). In the Late Permian, only the mountainous, northernmost regions of Siberia were covered by snow & ice. Global temperatures were lowest at the start of the Permian (11˚C) and rose steadily throughout the Permian. By the Late Permian, global temperatures were comparable to the temperatures that characterized the Neogene (15˚–17˚C). During the Permo-Triassic Extinction Event, global temperature rose to an astounding 40˚C.

The Paleozoic core of Pangea was assembled during the early Permian (280 Ma). Pangea was surrounded by subduction zones that dipped beneath its perimeter. The center of Pangea was cross-cut by the towering, E-W trending, Central Pangean Ranges. These mountains formed as a result of a series of Permo-Carboniferous continental collisions (C. & S. Appalachians, Ouachitas, Mauritanides, Hercynian & Variscan ranges). The Ural mountains were formed by the collision of Baltica, Kazakhstania, and Siberia in the early-mid Permian. In the Tethyan realm, the continent of Cimmeria rifted away from the NE margin of Gondwana due to the subduction of the PaleoTethyan mid-ocean ridge (300 Ma). Cimmeria was pulled northwards by subduction zones dipping beneath the southern margin of Central Asia. As Cimmeria moved northward, the southern half of Tethys (NeoTethys) expanded while the northern half of Tethys (PaleoTethys) contracted. The last remnant of ProtoTethys, which separated N. China from Amuria, was consumed during the Late Permian. The plate tectonics of the vast Panthalassic Ocean is unknown.

Sea level was highest during the Early Permian (+80 m), intermittently rose and fell throughout the Permian, and dramatically receded at the end of the Permian (-80 m). N-S shorelines and a strong latitudinal temperature gradient facilitated the formation of numerous biogeographic provinces in the Early Permian. These provinces gradually consolidated as global temperatures warmed.

Geological Society of America Abstracts with Programs. Vol. 52, No. 1

doi: 10.1130/abs/2020SC-343892

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