Influences of Atlantic Ocean thermohaline circulation and Antarctic ice-sheet expansion on Pliocene deep Pacific carbonate chemistry

Quantifying changes in seawater carbonate chemistry is crucial to deciphering of patterns and drivers of the oceanic carbon cycle and climate change. Here, we present a new deep-water carbonate ion saturation state (A[CO2- 3 ]) record for the Pliocene western tropical Pacific, reconstructed from the...

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Bibliographic Details
Published in:Earth and Planetary Science Letters
Main Authors: Qin, Bingbin, Li, Tiegang, Xiong, Zhifang, Algeo, Thomas J., Jia, Qi, Nurnberg, Dirk, Shi, Jiangnan
Format: Report
Language:English
Published: ELSEVIER 2022
Subjects:
shell weight
A[CO2-3 ]
Panamanian Gateway
glaciation
atmosphericpCO2
Site U1490
Geochemistry & Geophysics
SEA-SURFACE TEMPERATURES
PLANKTONIC-FORAMINIFERA
TROPICAL PACIFIC
SOUTHERN-OCEAN
NORTH-ATLANTIC
WATER
MA
CALCIFICATION
EVOLUTION
NEODYMIUM
Antarctic
Pacific
Southern Ocean
Antarc*
Ice Sheet
NADW
North Atlantic Deep Water
North Atlantic
Planktonic foraminifera
Sea ice
Online Access:http://ir.qdio.ac.cn/handle/337002/180294
https://doi.org/10.1016/j.epsl.2022.117868
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Summary:Quantifying changes in seawater carbonate chemistry is crucial to deciphering of patterns and drivers of the oceanic carbon cycle and climate change. Here, we present a new deep-water carbonate ion saturation state (A[CO2- 3 ]) record for the Pliocene western tropical Pacific, reconstructed from the size -normalized weight of the planktonic foraminifer Trilobatus sacculifer of IODP Site U1490. A steep decline in deep-water A[CO2- 3 ] occurred at similar to 4.6 Ma synchronous to the enhanced production of North Atlantic Deep Water (NADW) related to the closure of the Panamanian Gateway. Subsequently, at the onset of the Northern Hemisphere glaciation at similar to 2.7 Ma the weakening of NADW formation resulted in a deep -water A[CO2- 3 ] peak. The changes in NADW production rate likely controlled a seesaw-like fluctuation in deep-water A[CO2- 3 ] between the Pacific and Atlantic oceans. During the late Pliocene (similar to 3.8-2.8 Ma), Antarctic ice-sheet/sea-ice expansions sequestered CO2 in the deep Pacific through ventilation of the deep watermass, leading to a long-term decrease in deep Pacific A[CO2-3]. We infer that fluctuating NADW production rates at similar to 4.6 Ma and similar to 2.7 Ma influenced inter-basinal fractionation of deep-ocean carbon between the Atlantic and Pacific, and that deep Pacific carbon storage linked to expansions of Antarctic ice sheet/sea ice contributed to the lowering of atmospheric pCO2 and global cooling during the late Pliocene.(c) 2022 Elsevier B.V. All rights reserved.

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