Preliminary data from IODP Site U1338 of the Pacific Equatorial Age Transect (PEAT IODP Expedition 320/321): a study on the interaction between paleoenvironment and evolution of selected calcareous nannofossil taxa
Abstract
A continuous Cenozoic sediment record of the paleoequatorial Pacific ocean was recovered during IODP Expedition 320/321 (March-June 2009). The Pacific Equatorial Age Transect (PEAT) includes eight sites (U1331 to U1338), cored above the paleo-position of the equator at successive crustal ages on the Pacific plate, with records from the sediment surface to basement, with basalt aged between 53 to 18 Ma. The present study is focused on IODP Site 1338 that collected a 3-18 Ma segment of the PEAT equatorial megasplice. Although the target equatorial interval of Site 1338 was the middle and late Miocene, ~415 m of a complete sedimentary succession from Pleistocene to lower Miocene was recovered. Sediments are nannofossil ooze and chalk with varying concentrations (often relatively high abundances) of biosiliceous components, and show decimeter to meter lithological cycles that possibly reflect changes in production, dissolution, photic zone paleoecology. Ongoing analysis on nannofossil assemblages and selected taxa are providing distribution and abundance data that, combined with geochemical proxies, will unravel the biotic response to different climatic and oceanographic conditions. Biometric analysis and quantitative abundance analysis are used for providing a clear taxonomy of an important Neogene component of the nannofossil assemblages, the genus Discoaster, and for delineating in detail the evolutionary trends within the taxon. Moreover, we will try to relate the evolutionary signal observed in Discoaster lineage to the environmental evolution, namely to significant events such as the carbonate crash (Vincent and Berger, 1985; Lyle, et al., in prep.), the fluctuation and shallowing of the Calcite Compensation Depth (CCD) (Lyle, 2003), and deposition of diatom enriched intervals (Kemp and Baldauf, 1993).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMPP22B..06R
- Keywords:
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- 4944 PALEOCEANOGRAPHY / Micropaleontology;
- 4950 PALEOCEANOGRAPHY / Paleoecology;
- 9605 INFORMATION RELATED TO GEOLOGIC TIME / Neogene