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Deciphering the modern calcification depth of Globigerina bulloides in the southwestern Indian Ocean from its oxygen isotopic composition

DRS at CSIR-National Institute of Oceanography

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Title Deciphering the modern calcification depth of Globigerina bulloides in the southwestern Indian Ocean from its oxygen isotopic composition
 
Creator Saraswat, R.
Khare, N.
 
Subject Globigerina bulloides
planktic foraminiferal
foraminiferal species
Indian Ocean
 
Description The water depth at which the planktic foraminiferal species Globigerina bulloides calcifies its shell has been deciphered based on the oxygen isotopic composition of its shells in surface sediment samples collected from the southwestern Indian Ocean. The seawater temperature for water depths ranging from 0-200 m was estimated from G. bulloides delta sup(18)O by using various paleotemperature equations. Out of several paleotemperature equations, the one given by Epstein and others (1953) provided the best-fit results. Similarly, the estimated seawater salinity was calculated using the seawater delta sup(18)O calculated from G. bulloides delta sup(18)O, and measured seawater temperature taken from the Levitus database. A comparison of seawater salinity and temperature estimated from G. bulloides d delta sup(18)O, with the measured seawater salinity and temperature at different water depths, shows that the calcification depth of G. bulloides varies latitudinally. From the equator to approx. 15 degrees S, the calcification depth of G. bulloides was inferred to be approx. 75 m. Between 15 degrees S and approx. 43 degrees S, the estimated seawater temperature matched well with the seawater temperature at approx. 200 m water depth, indicating that the G. bulloides calcification depth was comparatively deeper in this region. Farther south of approx. 43 degrees S, however, the calcification depth appears to be considerably shallower than in the northern part of the study area. The comparison also showed that irrespective of latitudinal region, the estimated seawater temperature matches well with the seawater temperature during the austral spring season suggesting that G. bulloides is abundant at that time. The findings will help in paleoclimatic reconstruction studies based on characteristics of G. bulloides
 
Date 2010-07-30T09:35:53Z
2010-07-30T09:35:53Z
2010
 
Type Journal Article
 
Identifier Journal of Foraminiferal Research, vol.40(3); 220-230
http://drs.nio.org/drs/handle/2264/3677
 
Language en
 
Rights An edited version of this paper was published by The Cushman Foundation for Foraminiferal Research, Copyright [2010]. All efforts have been made to respect the copyright to the best of our
knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher Cushman Foundation for Foraminiferal Research