2 Reconstructing Paleo-Environmental Changes I

Thursday, 28 March 2019
8:00 AM - 12:00 PM
Gold Ballroom

TRANS-ATLANTIC REDOX RECORDS THROUGH A MID-SILURIAN EXTINCTION EVENT

Paper number: 2-4
Program: Theme Sessions
Time: 9:00 AM – 9:20 AM

Authors

Abstract

The Homerian Stage (upper Wenlock) of the Silurian has become associated with a rapid succession of extinction events that affected both planktic and (nekto)benthic organisms (the ‘Big Crisis’, ‘lundgreni Event’, ‘Mulde Event’). This mid-Silurian extinction interval coincides globally with a distinct positive carbon isotope excursion (CIE) and shifts in lithofacies signaling notable changes in sea level. A variety of interpretations have been brought forward to explain faunal turnover patterns and/or the CIE; sea-level records collectively indicate eustatic influence, and changes in climatic and oceanographic conditions are commonly invoked. Widespread marine anoxia has repeatedly been suggested as an important ‘kill mechanism’. We propose to test this and other scenarios by analyzing a suite of geochemical proxies across the extinction interval. Here we focus on a carbonate section at the Roberts Mountains, Nevada, USA, to pair δ13C with I/Ca and δ34SCAS (carbonate-associated sulfate) analyses in order to gain valuable information about paleoredox conditions. Additionally, we pair δ13C records with Fe speciation, trace metals, and δ34Spyrite analyses from time-equivalent strata of the shale-dominated Priekule drill core from Latvia. High-resolution multi-proxy data sets from two paleocontinents (Baltica & Laurentia) and sedimentary basins, together with distinctive lithologic successions and geochemical tools, will help to disentangle local/regional from global patterns of environmental and paleoredox perturbations.

Geological Society of America Abstracts with Programs. Vol. 51, No. 3

doi: 10.1130/abs/2019SE-327286

© Copyright 2019 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.