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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Morphotype and Crust Effects on the Geochemistry of Globorotalia inflata

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Author(s):
Jonkers, Lukas [1] ; Gopalakrishnan, Akshat [2] ; Wessel, Lea [2] ; Chiessi, Cristiano M. [3] ; Groeneveld, Jeroen [4] ; Monien, Patrick [2] ; Lessa, Douglas [5] ; Morard, Raphael [1]
Total Authors: 8
Affiliation:
[1] Univ Bremen, MARUM Ctr Marine Environm Sci, Bremen - Germany
[2] Univ Bremen, Dept Geosci, Bremen - Germany
[3] Univ Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo, SP - Brazil
[4] Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Potsdam - Germany
[5] Fed Fluminense Univ, Programa Posgrad Geoquim, Rio De Janeiro - Brazil
Total Affiliations: 5
Document type: Journal article
Source: PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY; v. 36, n. 4 APR 2021.
Web of Science Citations: 1
Abstract

Sedimentary specimens of the planktonic foraminifera Globorotalia inflata can provide information on subsurface conditions of past oceans. However, interpretation of their geochemical signal is complicated by possible effects of cryptic diversity and encrustation. Here we address these issues using plankton tow and sediment samples from the western South Atlantic, where two genotypes of G. inflata occur. To separate the genotypes, we analyzed shells from the extreme ends of the morphospace of G. inflata. The delta O-18 and delta C-13 of encrusted specimens from both morphotypes are indistinguishable. However, we do find a large influence of encrustation on delta O-18 and Mg/Ca. Whereas crust Mg/Ca ratios are at all locations lower than lamellar calcite, the crust effect on delta O-18 is less consistent in space. Plankton tows show that encrusted specimens occur at any depth and that even close to the surface crust Mg/Ca ratios are lower than in lamellar calcite. This is inconsistent with formation of the crust at lower temperature at greater depth. Instead we suggest that the difference between the crust and lamellar calcite Mg/Ca ratio is temperature-independent and due to the presence of high Mg/Ca bands only in the lamellar calcite. The variable crust effect on delta O-18 is more difficult to explain, but the higher incidence of crust-free specimens in warmer waters and the observation that a crust effect is clearest in the confluence zone, hint at the possibility that the difference reflects advective mixing of specimens from warmer and colder areas, rather than vertical migration. (AU)

FAPESP's process: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM)
Grantee:Cristiano Mazur Chiessi
Support Opportunities: Research Grants - Research Program on Global Climate Change - Young Investigators - Phase 2
FAPESP's process: 19/24349-9 - Assessing the effects of past and future climate change on Amazonian biodiversity (CLAMBIO)
Grantee:Cristiano Mazur Chiessi
Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants