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A Cenozoic terrestrial paleoclimate record from He dating and stable isotope geochemistry of goethites from Western Australia

Miller, Hayden B. D. and Vasconcelos, Paulo M. and Eiler, John M. and Farley, Kenneth A. (2017) A Cenozoic terrestrial paleoclimate record from He dating and stable isotope geochemistry of goethites from Western Australia. Geology, 45 (10). pp. 895-898. ISSN 0091-7613. https://resolver.caltech.edu/CaltechAUTHORS:20170829-133611502

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Abstract

Supergene goethites from the Hamersley region of Western Australia were analyzed for δ^(18)O and the results combined with both new and previously published (U-Th)/He ages to assess the paleoenvironmental signal recorded by surficial goethite in a long-term continental archive. Δ^(18)O_(goe) values increase monotonically by ∼3‰ between 71 Ma and 5 Ma and appear little affected by changes in temperature or other characteristics of depositional environment. The temporal trend likely reflects the isotopic composition of meteoric water from which the goethite formed, which varied as Australia migrated ∼3000 km northward over the Cenozoic. Translating age to paleolatitude reveals that the δ^(18)O_(goe) data are consistent with a latitudinal gradient in the δ^(18)O_(precip) that, throughout the Cenozoic, remained largely unchanged from the modern gradient. There is a 5‰ offset between the latitudinal trends of δ^(18)O_(goe) and modern precipitation, approximately as expected from the water-goethite fractionation factor. Temporal variation in the δ^(18)O of local meteoric water arising from changes in moisture source or pathway are not evident in the goethites, at least in part because topography is subdued and has evolved little in this tectonically quiescent landscape. Our results provide evidence that the efficiency of water transport from equator to pole that governs the latitudinal δ^(18)O gradient of precipitation has been roughly constant over southern temperate latitudes for the entirety of the Cenozoic.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1130/G38989.1DOIArticle
https://pubs.geoscienceworld.org/geology/article/45/10/895/353519/A-Cenozoic-terrestrial-paleoclimate-record-from-HePublisherArticle
ORCID:
AuthorORCID
Farley, Kenneth A.0000-0002-7846-7546
Additional Information:© 2017 Geological Society of America. Manuscript received 23 January 2017; Revised manuscript received 17 June 2017; Manuscript accepted 21 June 2017. Published: 04 August 2017.
Issue or Number:10
Record Number:CaltechAUTHORS:20170829-133611502
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170829-133611502
Official Citation:Hayden B.D. Miller, Paulo M. Vasconcelos, John M. Eiler, Kenneth A. Farley; A Cenozoic terrestrial paleoclimate record from He dating and stable isotope geochemistry of goethites from Western Australia. Geology ; 45 (10): 895–898. doi: https://doi.org/10.1130/G38989.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:80908
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:29 Aug 2017 20:53
Last Modified:03 Oct 2019 18:36

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