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Evaluation of oxygen isotope and Sr/Ca ratios from a Maldivian scleractinian coral for reconstruction of climate variability in the northwestern Indian Ocean

David Storz, Eberhard Gischler, Jens Fiebig, Anton Eisenhauer and Dieter Garbe-Schoenberg
Evaluation of oxygen isotope and Sr/Ca ratios from a Maldivian scleractinian coral for reconstruction of climate variability in the northwestern Indian Ocean
Palaios (January 2013) 28 (1): 42-55

Abstract

Corals are important marine archives for high-resolution reconstructions of low-latitude climate variability in preinstrumental and historical periods. Herein, we present monthly-resolved records of delta (super 18) O and Sr/Ca for the 20th century (1917-2007) from a Porites lutea colony from the Maldives (northwestern Indian Ocean). Previous studies of annual mean extension rates of this coral revealed a distinct dependency of coral growth on variations of sea surface temperature (SST) and hydraulic energy, driven by El Nino-Southern Oscillation (ENSO) and southwestern Indian monsoon forcing. This enables the investigation of coral delta (super 18) O and Sr/Ca ratios from the Maldives as archives of historical ENSO and Indian monsoon variability. Unlike other locations in the Indian Ocean, correlation of delta (super 18) O and SST is weak (r = -0.42; p < 0.001), suggesting interferences of SST and seawater delta (super 18) O at the location. These interferences probably caused significantly weaker interannual ENSO signatures in delta (super 18) O as evident in the extension rates of our coral and in geochemical proxies measured at other sites in the northwestern Indian Ocean. Sr/Ca ratios show bias by nontemperature effects, and were not used to estimate seawater delta (super 18) O and salinity. Strong decadal variability (10-14 years) in delta (super 18) O, indicative of a Pacific ENSO signal, is not found in instrumental SST, and could be explained by variations in salinity. Interannual and decadal monsoon variability (6-7 yrs and 18-19 yrs), found in the extension rates, was not found in delta (super 18) O, suggesting, in agreement with other studies, that geochemical coral proxy records from the northwestern Indian Ocean do not capture temporal variations of the Indian monsoon strength.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 28
Serial Issue: 1
Title: Evaluation of oxygen isotope and Sr/Ca ratios from a Maldivian scleractinian coral for reconstruction of climate variability in the northwestern Indian Ocean
Affiliation: Goethe-Universitaet, Institut fuer Geowissenschaften, Frankfurt am Main, Germany
Pages: 42-55
Published: 201301
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 91
Accession Number: 2013-021300
Categories: Quaternary geologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
N04°17'60" - N04°17'60", E72°58'60" - E72°58'60"
Secondary Affiliation: Helmholtz-Zentrum fuer Ozeanforschung, DEU, GermanyChristian-Albrechts-Universitaet zu Kiel, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201314
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