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A high-resolution record of early Paleozoic climate

Goldberg, Samuel L. and Present, Theodore M. and Finnegan, Seth and Bergmann, Kristin D. (2021) A high-resolution record of early Paleozoic climate. Proceedings of the National Academy of Sciences of the United States of America, 118 (6). Art. No. e2013083118. ISSN 0027-8424. https://resolver.caltech.edu/CaltechAUTHORS:20210202-083128097

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Abstract

The spatial coverage and temporal resolution of the Early Paleozoic paleoclimate record are limited, primarily due to the paucity of well-preserved skeletal material commonly used for oxygen-isotope paleothermometry. Bulk-rock δ¹⁸O datasets can provide broader coverage and higher resolution, but are prone to burial alteration. We assess the diagenetic character of two thick Cambro–Ordovician carbonate platforms with minimal to moderate burial by pairing clumped and bulk isotope analyses of micritic carbonates. Despite resetting of the clumped-isotope thermometer at both sites, our samples indicate relatively little change to their bulk δ¹⁸O due to low fluid exchange. Consequently, both sequences preserve temporal trends in δ¹⁸O. Motivated by this result, we compile a global suite of bulk rock δ¹⁸O data, stacking overlapping regional records to minimize diagenetic influences on overall trends. We find good agreement of bulk rock δ¹⁸O with brachiopod and conodont δ¹⁸O trends through time. Given evidence that the δ¹⁸O value of seawater has not evolved substantially through the Phanerozoic, we interpret this record as primarily reflecting changes in tropical, nearshore seawater temperatures and only moderately modified by diagenesis. Focusing on the samples with the most enriched, and thus likely least-altered, δ¹⁸O values, we reconstruct Late Cambrian warming, Early Ordovician extreme warmth, and cooling around the Early–Middle Ordovician boundary. Our record is consistent with models linking the Great Ordovician Biodiversification Event to cooling of previously very warm tropical oceans. In addition, our high-temporal-resolution record suggests previously unresolved transient warming and climate instability potentially associated with Late Ordovician tectonic events.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1073/pnas.2013083118DOIArticle
https://www.pnas.org/content/suppl/2021/02/01/2013083118.DCSupplementalPublisherSupporting Information
https://doi.org/10.26022/IEDA/111716DOIData
ORCID:
AuthorORCID
Goldberg, Samuel L.0000-0001-8215-2400
Present, Theodore M.0000-0002-4747-2174
Finnegan, Seth0000-0002-6175-6173
Bergmann, Kristin D.0000-0002-6106-2059
Additional Information:© 2021 National Academy of Sciences. Published under the PNAS license. Edited by Mark Thiemens, University of California San Diego, La Jolla, CA, and approved January 11, 2021 (received for review July 6, 2020). Fieldwork in Newfoundland was conducted by Samuel Goldberg, Marjorie Cantine, and Kristin Bergmann. Fieldwork in Spitsbergen was conducted under Permit 2016/00110-2 by Melanie Hopkins (American Museum of Natural History), Björn Kröger (Finnish Museum of Natural History), Seth Finnegan (University of California Berkeley), Franziska Franeck (Natural History Museum Oslo), and Håvard Kårsted (Longyearbyen), and made possible by funding from the Niarchos Foundation, the National Geographic Society, and the Societas Scientarium Fennica. This work is part of Research in Svalbard ID 10467. We thank Adam Jost and other members of the K.D.B. laboratory for substantial help with sample analysis and instrument troubleshooting. We thank the editor and two anonymous reviewers for comments on a previous version of the manuscript; their suggestions have strengthened and clarified the paper. S.L.G. was supported by a NASA Earth and Space Science Fellowship. S.F. and K.D.B. were supported by the Packard Foundation. Data Availability: Clumped-isotope measurements are available in Datasets S1–S3 and in the EarthChem repository (DOI: 10.26022/IEDA/111716). Author contributions: S.L.G. and K.D.B. designed research; S.L.G., S.F., and K.D.B. performed research; S.L.G., T.M.P., S.F., and K.D.B. analyzed data; and S.L.G., T.M.P., S.F., and K.D.B. wrote the paper. The authors declare no competing interest. This article is a PNAS Direct Submission. This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2013083118/-/DCSupplemental.
Funders:
Funding AgencyGrant Number
NASA Earth and Space Science Fellowship80NSSC18K1324
David and Lucile Packard Foundation2018-68044
Subject Keywords:paleoclimate; Ordovician; oxygen isotope; biodiversification
Issue or Number:6
Record Number:CaltechAUTHORS:20210202-083128097
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210202-083128097
Official Citation:A high-resolution record of early Paleozoic climate. Samuel L. Goldberg, Theodore M. Present, Seth Finnegan, Kristin D. Bergmann. Proceedings of the National Academy of Sciences Feb 2021, 118 (6) e2013083118; DOI: 10.1073/pnas.2013083118
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107847
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Feb 2021 16:50
Last Modified:02 Feb 2021 16:50

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