Tropical Atlantic coccolith Sr/Ca productivity records from the Paleocene-Eocene Thermal Maximum

Author(s): Matell, Nora; Theberge, Ashleigh; Stoll, Heather M.; Shimuzu, Nobumichi
Author Affiliation(s): Primary:
Williams College, Department of Geoscience, Williamstown, MA, United States
Woods Hole Oceanographic Institution, United States
Volume Title: Geological Society of America, Northeastern Section, 40th annual meeting
Source: Abstracts with Programs - Geological Society of America, 37(1), p.76; Geological Society of America, Northeastern Section, 40th annual meeting, Saratoga Springs, NY, March 14-16, 2005. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: One hypothesis explaining the rapid recovery of temperature and atmospheric carbon following the PETM involves increased primary marine productivity and subsequent carbon burial in deep ocean sediments. The tropics, which contain the majority of the world's oceanic surface area, are of particular importance in evaluating the geographic extent of this proposed feedback. Previous research is limited to sites in the Antarctic (ODP site 690) and the mid-latitude Pacific (ODP site 1209). Here we present Sr/Ca of coccoliths as a proxy for productivity changes at ODP site 1258 Demerara Rise in the tropical Atlantic. Sr/Ca incorporation in coccoliths has been shown to be positively correlated with productivity. We measured Sr/Ca in bulk samples of two different size sediment fractions (5-8 µm and 8-12 µm) via Atomic Absorption Spectroscopy, and in individually picked coccoliths of several genera using Secondary Ion Mass Spectrometry ion probe. This allows us to isolate the productivity responses of specific genera. Sample depths ranged from 176.0 mbsf to 171.75 mbsf, providing data points encompassing the PETM and the surrounding time period. Toweius showed a large decrease in productivity during the PETM, eventually recovering to near pre-PETM levels. In contrast, Coccolithus pelagicus showed an increase in productivity during the event. Bulk data for the 5-8 µm and 8-12 µm sediment fractions showed similar trends to Toweius and C. pelagicus, respectively. The presence of additional genera in the bulk samples accounts for minor deviations from the genus specific data. The difference in the productivity response of these two genera is likely due to varied modification of their respective ecological niches produced by the conditions of the PETM. Combined with previous research from OPD sites 690 and 1209, the data indicate that there was no unified coccolithophorid response to the PETM. In the tropics and mid-latitudes, there are examples of both productivity increases and decreases among different genera, whereas in the high latitudes all studied genera appear have increased or constant productivity.
Year of Publication: 2005
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Alkaline earth metals; Atlantic Ocean; Biochemistry; Calcium; Cenozoic; Coccolithophoraceae; Coccolithus; Coccolithus pelagicus; Demerara Rise; Eocene; Equatorial Atlantic; Experimental studies; Geochemical indicators; Geochemistry; Ion probe data; Leg 113; Leg 198; Leg 207; Lower Eocene; Marine environment; Mass spectra; Metals; Microfossils; North Atlantic; Northwest Atlantic; ODP Site 1209; ODP Site 1258; ODP Site 690; Ocean Drilling Program; PETM; Pacific Ocean; Paleocene; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleoecology; Paleogene; Paleotemperature; Plantae; Southern Ocean; Spectra; Sr/Ca; Strontium; Tertiary; Tropical environment; Upper Paleocene
Coordinates: S650938 S650937 E0011218 E0011218
N092600 N092600 W0544400 W0544400
N323900 N324000 E1583100 E1583000
Record ID: 2006042582
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