T153 Mesozoic Earth System and Timescale

Tuesday, 24 September 2024
8:00 AM - 12:00 PM
212A

FLOODING, FIRES AND FORESTS: THE TRANSITION TO MODERN GLOBAL CLIMATE AT THE END OF THE LATE TRIASSIC, A VIEW FROM THE PALEO-ANTARCTIC

Paper number: T153-2
Program: Technical Sessions
Time: 8:10 AM – 8:25 AM

Authors

Abstract

The Late Triassic Carnian–Norian era marked a significant period of global climatic changes, often associated with a shift from arid to more humid conditions, known as the Carnian Pluvial Episode (CPE). This transition towards a more humid climate during the CPE is frequently attributed to the emplacement of the Wrangellia Large Igneous Province, ~233 million years ago in northern Panthalassa. During this time Tasmania was located at a paleolatitude 62-74° S, today occupied by the frozen rocky Antarctic continent. Sedimentary archives of the Late Triassic from Tasmania thus present a unique opportunity to examine a high-latitude archive of a world that was in a significant state of climatic and environmental flux. Here, we present new sedimentological and geochemical proxy data, including organic carbon isotopes, biomarkers, elemental data (Hg/TOC and XRF data), and Scanning Electron Microscopy imagery of charred plant residues from two continental cores in Eastern Tasmania. These cores represent the deposition of organic-rich fluvial-lacustrine sediments that span the late Ladinian through the earliest Rhaetian deposits of the Upper Parmeener Supergroup. Organic carbon isotopes reveal a series of excursions indicative of the CPE and the mid-Norian. Initial findings from n-alkanes and polycyclic aromatic hydrocarbons (PAHs) indicate an escalation in soil erosion during the Carnian, evidenced by elevated concentrations of dibenzofuran and dibenzothiophene. An increase in retene concentrations as well as elemental data including increased smectite also supports enhanced terrestrial inputs, likely related to the intensification of the hydrological cycle during the Carnian. Concentrations of total PAHs encompassing 3 to 7 rings, typically associated with biomass burning, indicate a probable intensification of wildfire activity, potentially influenced by a transition towards more humid conditions with increased terrestrial productivity interrupting warmer and more arid conditions, creating a catalyst for enhanced wildfire activity. This study offers a record of the impact and repercussions of an extreme climatic episode at high latitudes within the paleo-Antarctic circle which may offer insights in to the potential changes Antarctica may undergo due to anthropogenically induced climatic change.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-403881

© Copyright 2024 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.