Well-preserved calcareous nannofossils across the Paleocene–Eocene Thermal Maximum, International Ocean Discovery Program (IODP) Site U1580, central Agulhas Plateau, southwestern Indian Ocean


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Gabriele.Uenzelmann-Neben [ at ] awi.de

Abstract

The Paleocene-Eocene Thermal Maximum (PETM) was an abrupt and extreme warming event associated with rapid input of light carbon into the ocean-atmosphere system. The carbon cycle perturbations during the PETM caused significant changes to marine plankton, including extinction of some benthic foraminifers and the appearance of malformed calcareous nannoplankton, possibly related to ocean acidification during the event. The PETM is now considered a potential analog for the effects of anthropogenic climate change due to its rapid onset; thus, study of PETM records offers an opportunity to better understand the potential effects of rapid climate change on marine phytoplankton communities. Here we present calcareous nannofossil assemblage data across a newly recovered PETM section from International Ocean Discovery Program (IODP) Site U1580, drilled on the central Agulhas Plateau during IODP Expedition 392 in early 2022. Present water depth at this site is 2560 m and it sits at 40° 47.15’S, although the site has moved progressively northward since the Agulhas Plateau formed in the mid-Cretaceous, when the site was located about 20° further south. The PETM interval was identified during the expedition by a change in sediment color, increase in magnetic susceptibility, and calcareous nannofossil assemblages. Low-resolution bulk 13C measurements conducted following the expedition confirm a negative isotope excursion and decrease in calcium carbonate content across the interval. The shipboard age model based on nannofossil and planktonic foraminifer biostratigraphy, together with magnetostratigraphy, suggests relatively high sedimentation rates (~2.5 cm/kyr). Nannofossil assemblages are quite well preserved, with PETM-specific taxa present including Rhomboaster calcitrapa, Rhomboaster cuspis, Rhomboaster bramlettei, Discoaster araneus, and Discoaster acutus. Initial qualitative analyses indicate Zygrhablithus bijugatus is particularly abundant within the PETM interval, whereas Fasciculithus spp. decrease in abundance. Discoaster spp. are also more abundant in the earliest Eocene, as are Neochiastozygus spp. Neococcolithes spp., and Ellipsolithus bollii. The position of this new site between Maud Rise Site 690 and Walvis Ridge Sites 1262, 1263, and 1265 should shed new light on this event in the southern mid-latitudes.



Item Type
Conference (Poster)
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Helmholtz Cross Cutting Activity (2021-2027)
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Not peer-reviewed
Publication Status
Published
Event Details
CBEP12, 22 Aug 2022 - 25 Aug 2022.
Eprint ID
56225
Cite as
Kulhanek, D. K. , Archontikis, O. A. , Herrle, J. O. , Penman, D. E. , Bohaty, S. M. , Westerhold, T. , Burkett, A. M. , Sprain, C. J. , Batenburg, S. J. , Uenzelmann-Neben, G. and Childress, L. B. , IODP Expedition 392 Science Party (2022): Well-preserved calcareous nannofossils across the Paleocene–Eocene Thermal Maximum, International Ocean Discovery Program (IODP) Site U1580, central Agulhas Plateau, southwestern Indian Ocean , CBEP12, 22 August 2022 - 25 August 2022 .


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