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Lübbers, Julia; Kuhnt, Wolfgang; Holbourn, Ann E.; Bolton, Clara T.; Gray, Emmeline; Usui, Yoichi; Kochhann, Karlos G. D.; Beil, Sebastian and Andersen, Nils
(2019).
DOI: https://doi.org/10.1029/2018PA003482
Abstract
We integrate benthic foraminiferal stable isotopes, X‐ray fluorescence elemental ratios, and carbonate accumulation estimates in a continuous sedimentary archive recovered at International Ocean Discovery Program Site U1443 (Ninetyeast Ridge, Indian Ocean) to reconstruct changes in carbonate deposition and climate evolution over the interval 13.5 to 8.2 million years ago. Declining carbonate percentages together with a marked decrease in carbonate accumulation rates after ~13.2 Ma signal the onset of a prolonged episode of reduced carbonate deposition. This extended phase, which lasted until ~8.7 Ma, coincides with the middle to late Miocene carbonate crash, originally identified in the eastern equatorial Pacific Ocean and the Caribbean Sea. Interocean comparison reveals that intense carbonate impoverishment at Site U1443 (~11.5 to ~10 Ma) coincides with prolonged episodes of reduced carbonate deposition in all major tropical ocean basins. This implies that global changes in the intensity of chemical weathering and riverine input of calcium and carbonate ions into the ocean reservoir were instrumental in driving the carbonate crash. An increase in U1443 Log (Ba/Ti) together with a change in sediment color from red to green indicate a rise in organic export flux to the sea floor after ~11.2 Ma, which predates the global onset of the biogenic bloom. This early rise in export flux from biological production may have been linked to increased advection of nutrients and intensification of upper ocean mixing, associated with changes in the seasonality and intensity of the Indian Monsoon.
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About
- Item ORO ID
- 62404
- Item Type
- Journal Item
- ISSN
- 2572-4517
- Project Funding Details
-
Funded Project Name Project ID Funding Body Not Set Ku649/36‐1 Deutsche Forschungsgemeinschaft (DFG) Not Set IMonsoon ANR‐16‐CE01‐0004‐01 Agence Nationale de la Recherche - Keywords
- Carbonate crash; Indian Ocean; biogenic bloom; benthic stable isotopes; carbonate dissolution
- Academic Unit or School
-
Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM) - Copyright Holders
- © 2019 American Geophysical Union
- Depositing User
- Emmeline Gray