T19 Mass Extinction Causality: Records of Anoxia, Acidification, and Global Warming during Earth's Greatest Crises I

Sunday, 1 November 2015
8:00 AM - 12:00 PM
Room 310

VOLCANIC INDUCED ENVIRONMENTAL STRESS DURING THE END-TRIASSIC EVENT

Paper number: T19-9
Program: Technical Sessions
Time: 10:00 AM – 10:15 AM

Authors

Abstract

The end-Triassic biotic crisis is generally explained by massive input of CO2 and/or methane to the atmosphere linked to the formation of the large igneous province called the Central Atlantic Magmatic Province (CAMP). Such massive volcanism can be compared to industrial pollution releasing large amounts of the greenhouse gases CO2 and SO2 to the atmosphere. Indeed, the fossil record provides evidence of major perturbations in the δ13C-record of both calcareous and organic material. In the marine realm loss of calcifying organisms provides evidence of ocean acidification due to the increased pCO2, while in the terrestrial realm physiological responses in fossil plants indicate intense global warming across the Triassic-Jurassic boundary (TJB). Changing climatic conditions is further indicated by charcoal records from Greenland, Denmark, Sweden and Poland showing increased wildfire activity. Increased reworking of palynological material and marked changes in fluvial style in terrestrial successions seem to indicate an increased hydrological cycle.

In order to assess volcanic induced environmental stress from the CAMP across the TJB we compare two proxies that may both, each in their own way, indicate volcanic pollution, namely aberrant spores/pollen and mercury loading. The quantitative abundances of aberrant, i.e. abnormal, and thus probably non-viable pollen and spores are often used to assess environmental impact at polluted sites. Today the primary anthropogenic phytotoxic air pollutants include fluoride, O3, and SO2. In deep-time, volcanism would basically be the only source that provided larger amounts of e.g. flourides and SO2 to the atmosphere. Similarly, mercury (Hg) is one of the most toxic elements on the planet, with volcanic emissions providing the largest natural input to the Hg-cycle. The temporal distribution of Hg in relation to organic matter can provide evidence of atmospheric Hg loading on the marine ecosystem. We will present and compare the mercury and aberrant spore/pollen records from the stratigraphically well-constrained Triassic-Jurassic boundary successions in the Danish and German Basins, and discuss the possible impact of these data on the interpretation of events during end-Triassic biotic crisis.