Geological Society of America

T37 Paleoenvironmental Reconstructions from Biogenic Carbonates (Posters)

Sunday, 4 November 2018
9:00 AM - 5:30 PM
Halls J-K

CLUMPED ISOTOPE SYSTEMATICS IN LACUSTRINE AND FLUVIAL CARBONATES: A TOOL FOR PALEOCLIMATE, PALEOHYDROLOGY, AND PALEOALTIMETRY

Paper number: T37-1
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Alexandrea J. Arnold Presenting Author
University of California, Los Angeles, Los Angeles, CA
Robert Dunbar
Stanford Univ, Stanford, CA
James Russell
Brown University, Providence, RI
Stefan Lalonde
European Institute for Marine Studies, Plouzane
Charles G. Oviatt
Kansas State University, Manhattan, KS
Priyadarsi D. Roy
Universidad Nacional Autónoma de México, Mexico City
Robert Eagle
University of California, Los Angeles, Los Angeles, CA
Aradhna Tripati
19963 Observation DriveEarth, Planetary, and Space Sciences, Topanga, CA
John Mering
University of Waikato, Hamilton
Lauren Santi
University of California, Los Angeles, Los Angeles, CA
Victoria Petryshyn
University of Southern California, Los Angeles, CA
Bryce A. Mitsunaga
University of California, Los Angeles, Los Angeles, CA
John Wilson
California State University, Bakersfield, Bakersfield, CA
Daniel E. Ibarra
Stanford University, Stanford, CA
Darrell Kaufman
Northern Arizona University, Flagstaff, AZ
Andrew Cohen
University of Arizona, Tucson, AZ

Abstract

Our capacity to understand Earth’s environmental history is highly dependent on the accuracy of reconstructions of past climates. Lacustrine and riverine sediments provide important archives of terrestrial climate change, and represent an important tool for reconstructing paleoclimate, paleohydrology, and paleoaltimetry. Carbonate clumped isotope thermometry in particular presents a valuable opportunity to reconstruct past climates, using the abundance of ¹³C—¹⁸O bonds in carbonate sediments. Previous studies of synthetic carbonates have consistently found that cold formation temperatures are associated with a greater “clumping” of heavy ¹³C—¹⁸O bonds, and a limited amount of data for modern lake carbonates supports these findings. Here we present an extensive calibration dataset comprised of 111 analyses of 34 modern freshwater samples, including microbialites, tufas, micrites, endogenic carbonates, freshwater gastropods, bivalves, and ooids. To create this dataset, measurements of ¹³C¹⁸O¹⁶O were made on CO₂ produced by the dissolution of carbonate minerals in phosphoric acid, and these results are compared to independently known estimates of water temperature. The utility of this study is that it provides a foundation for the intercomparison and calibration of carbonate clumped isotope results from modern rivers and lakes, and also shows how we can best approach paleoenvironmental reconstructions using freshwater archives. We evaluate the use of a common calibration and material-specific calibrations, and find that material-specific calibrations may be most appropriate for such systems, with slopes ranging from 0.376 to 0.575 and intercepts ranging from 0.04346 to 0.2571. We also show that of existing synthetic calibrations, if a single slope calibration is used for all data, Tang et al. (2014) and Kelson et al. (2015) yields the most accurate results. This work constrains the relationship between independent estimates of water temperature and clumped isotope-derived temperatures (Δ₄₇) in modern lake carbonates, which has implications for paleoclimate studies on natural carbonate sediments.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-325115

© Copyright 2018 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.