Cenozoic planktonic foraminiferal palaeoecology inferred from isotopic and trace element geochemical signals
Abstract
The trace element and isotopic geochemistry of planktonic foraminiferal species, both in recent and deep time, is affected by their ecology. However, foraminifera have been known to adapt their ecologies, in response to physical and biogeochemical changes in the ocean. This adds uncertainty to proxy signals used to construct long-term palaeoclimate records. Therefore, validating ecology is particularly important for species used to reconstruct intervals of dramatic climate change in Earth history, such as the Paleocene-Eocene Thermal Maximum, and the Middle Miocene Climatic Optimum.
We adopt a multi-proxy approach to investigate the palaeoecology of multiple Eocene and Miocene species using individual foraminifera analysis (IFA). IFA enables potential heterogeneity of geochemical signatures within individuals in a population to be evaluated. Using well preserved specimens from various size fractions, we acquired paired carbon and oxygen isotope and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) data, and electron microprobe analysis (EMPA) trace element data for species with unresolved palaeoecologies from New Jersey (ODP Leg 174AX), Maryland (South Dover Bridge), Hampden Beach, Tanzania and Site U1338 (IODP Expedition 320/321, eastern equatorial Pacific). LA-ICPMS data, and Mg/Ca trace element maps of specimens from South Dover Bridge will be presented, and the palaeoecological and palaeoclimatic interpretations discussed. LA-ICPMS single chamber and size constrained data of Eocene species (except Globigerina cf. bulloides) suggest minimal effect of ontogeny on Mg/Ca, B/Ca and Sr/Ca. EMPA derived Mg/Ca maps of Eocene and Miocene species show intra-shell Mg/Ca heterogeneity alike to modern species, and Mg/Ca band thickness also varies between symbiotic and asymbiotic species.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP44A..06B
- Keywords:
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- 0419 Biomineralization;
- BIOGEOSCIENCESDE: 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 4924 Geochemical tracers;
- PALEOCEANOGRAPHYDE: 4994 Instruments and techniques;
- PALEOCEANOGRAPHY