Geological Society of America

T112 Oceans and Climates through Earth History: Modeling, Proxy, and Proxy Development Studies (Posters)

Monday, 23 September 2024
8:00 AM - 5:30 PM
Hall D

ASSESSING EARLY LAND PLANT IMPACTS ON THE EVOLVING PALEOZOIC MARINE BIOSPHERE

Paper number: T112-5
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Ginny Winters Presenting Author
University of California Riverside, Riverside, CA
Erik A. Sperling
Stanford University, Stanford, CA
Emily Ellefson
Stanford University, Stanford, CA
Lidya Tarhan
Yale University, New Haven, CT
Michael Melchin
St. Francis Xavier University, Antigonish, NS
Keith Dewing
Calgary, AB
Gordon Love
University of California, Riverside, Riverside, CA

Abstract

The Late Ordovician-Devonian transition was a critical interval of environmental and ecological change, with the radiation and diversification of early land plants and changes in marine carbon and nutrient cycling contributing to a major protracted change in the global biosphere. The emergence of early land plants may have contributed to a rise in atmospheric oxygen during the Paleozoic Era, alongside a hypothesized flux of terrestrial organic carbon and marine delivered nutrients, which could have significantly perturbed marine carbon and other biogeochemical cycles. However, the magnitude, timing, and global influence of this terrestrial chemical flux on climate, ocean chemistry and biological productivity remains poorly constrained. Notably, Late Ordovician-Silurian-Devonian lipid biomarker records tracking the rise of terrestrial carbon input into the marine realm are sparse.

An extensive set of thermally well-preserved Paleozoic sedimentary rocks from Bathurst Island, Arctic Canada, and from Alaska, were collected and are undergoing a detailed organic geochemical investigation to determine: i) early plant lipid contributions to ancient marine organic matter, and ii) changes in marine primary productivity for Ordovician, Silurian and Devonian shelf/slope settings in these locations. Increasing land plant input to ancient sedimentary organic matter may be recorded as an increase in the relative and absolute abundances of waxy n-alkanes (C₂₃-C₃₃) and/or plant (bryophytes and early tracheophytes) terpenoids. Secular changes in marine phytoplankton compositions have been recognized in our study by the distribution of steroid, hopanoid and other terpenoids using selective multiple reaction monitoring (MRM)-gas chromatography-mass spectrometry. Our investigation will help better constrain the composition of marine communities through the Late Ordovician-Devonian transition and help untangle the cryptic influence of progressive continental greening in perturbing the Paleozoic marine biosphere.

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

doi: 10.1130/abs/2024AM-403158

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