T305 Impact of Extinction Events on the Ecological and Geochemical Functioning of Marine Ecosystems

Wednesday, 25 October 2017
8:00 AM - 12:00 PM
Room 608

IN WAKE OF END PERMIAN EXTINCTION, WIDESPREAD NUTRIENT CRISIS LEADS TO EARLY TRIASSIC PRODUCTIVITY COLLAPSE ACROSS NW PANGEA

Paper number: T305-13
Program: Technical Sessions
Time: 11:00 AM – 11:15 AM

Authors

Abstract

The Latest Permian Extinction, the most severe extinction in Earth history, was followed by a prolonged 5-9 ma period of biotic recovery. What factors limited recovery are still uncertain and debated. We examined the N isotope record through Later Permian to Middle Triassic sediments deposited along the NW margin of Pangea to examine nutrient availability during the post-extinction Early Triassic hothouse, from the Festningen section in Spitzbergen. Results show progressive decline of N isotope values through the Early Triassic to values near atmospheric, suggesting reduced nutrient upwelling and progressively greater reliance on atmospheric N fixation to support marine primary productivity. This is paralleled by a significant drop in total organic carbon content as well as primary productivity proxies (element enrichment factors of Ba, Zn, Ni), indicating that nutrient stress limited marine productivity through the Early Triassic. These results are consistent with those of the Sverdrup Basin in the Canadian Arctic, indicating that nutrient stress was widespread across NW Pangea. Extreme sea temperature may be a factor limiting upwelling during this time. The Middle Triassic marks return to normal marine temperatures and return to a highly productive margin on NW Pangea, characterised by widespread deposition of organic rich phosphatic black shales.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-295713

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