T87 New Voices in Geobiology

Monday, 10 October 2022
8:00 AM - 12:00 PM
507

PALEOENVIRONMENTAL AND EVOLUTIONARY PATTERNS IN CAMBRIAN–ORDOVICIAN BIOTURBATION

Paper number: T87-9
Program: Technical Sessions
Time: 9:50 AM – 10:10 AM

Authors

  • Lidya Tarhan Presenting Author
    Yale University, Dept. Earth and Planetary Sciences, New Haven, CT

Abstract

Bioturbation—sediment mixing and ventilation by burrowing animals—shapes seafloor ecology, sediment properties and biogeochemical cycling throughout the modern oceans. The early Paleozoic emergence of bioturbating animals has therefore long been assumed to have led to substantial changes in marine biogeochemistry, ecosystem structure and the preservation potential of both sedimentary and fossil archives. However, the timing of the rise of bioturbation and environmental patterns in its expansion have been subjects of sustained debate—resolution of which has been hampered, in part, by a paucity of high-resolution bioturbation data or of systematic investigations of facies trends in lower Paleozoic bioturbation. Integrated sedimentological and ichnological characterization of the Cambrian–Ordovician Port au Port succession and Cow Head Group of western Newfoundland, encompassing over 350 meters of stratigraphy logged at the sub-decimeter scale, provides an ideal opportunity to address these questions. Across a wide range of marine facies, bioturbation does not, on average, exceed moderate intensities—corroborating observations from other lower Paleozoic successions indicating that the early Paleozoic development of bioturbation was a protracted process. Moreover, bioturbation intensities in the Port au Port succession and Cow Head Group are characterized by considerable variability at even fine scales of stratigraphic resolution and correlate strongly with variability in sedimentary facies. Facies recording nearshore depositional environments and carbonate-rich lithologies are each characterized by the highest intensities of both burrowing and sediment-mixing. These data highlight the need for a high-resolution and facies-specific approach to reconstructing the evolutionary history of bioturbation and suggest that, in contrast to previous models, bioturbation levels increased earlier in onshore relative to offshore marine settings.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-378635

© Copyright 2022 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.