Paleoecologic Controls on Early Triassic Refugia Distribution

Abstract

The end-Permian extinction (~252 ma) was the largest extinction event to have occurred during the Phanerozoic, resulting in the elimination of up to 78% of marine genera. Recovery from such a catastrophic event did not occur until the Middle Triassic, likely owing to prolonged environmental stress. Many have speculated as to the process with which marine ecosystems recovered following this event. The development of marine refugia, sanctuaries to which organisms migrate during time of environment stress, is one hypothesis. The focus of this thesis is to examine the distribution of marine refugia during the end-Permian extinction. Geochemical and paleoecologic data suggest that mid-depth settings deposited under oxic conditions are conducive to the development of refugia, by offering relief from lethally hot sea surface temperatures. In contrast, geochemical and paleoecologic data collected from two open Panthalassic seamounts suggest that these settings are not conducive to the development of marine refugia, potentially due to decreases in immigration rates owing to the development of a temperature barrier between oceanic islands and the continental margin.