Orbital forcing and evolution of the Southern African Monsoon from IODP Site U1476 within latest Miocene (7.4 Ma) to early Pliocene (4.5 Ma) interval

Marine sediments from the western Indian Ocean are potentially an ideal archive for monitoring local changes in the Southern African Monsoon (SAFM) as riverine discharge fluctuations are controlled by monsoon precipitation linked to the Intertropical Convergence Zone movement. Regarding the pottenti...

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Bibliographic Details
Main Authors: Azevedo, Allana, Jiménez-Espejo, Francisco Jose, Bulian, Francesca, Sierro, Francisco Javier, Tangunan, Deborah N, Takashimizu, Yasuhiro, Albuquerque, Ana Luiza Spadano, Kubota, Kaoru, Escutia, Carlota, Norris, Richard D, Hemming, Sidney R, Hall, Ian R
Format: Other/Unknown Material
Language:English
Published: PANGAEA 2023
Subjects:
Integrated Ocean Drilling Program / International Ocean Discovery Program
IODP
Antarctic
Indian
Antarc*
Ice Sheet
Planktonic foraminifera
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.961179
https://doi.org/10.1594/PANGAEA.961179
Description
Summary:Marine sediments from the western Indian Ocean are potentially an ideal archive for monitoring local changes in the Southern African Monsoon (SAFM) as riverine discharge fluctuations are controlled by monsoon precipitation linked to the Intertropical Convergence Zone movement. Regarding the pottential role played by the SAFM in climate systems from latest Miocene to early Pliocene, we reconstructed this monsoonal system based on elemental geochemistry (Ca/Ti and Si/K ratios), stable isotope geochemistry (δ18O and δ13C recorded in the planktonic foraminifera Orbulina universa), and marine sediment grain size data from the International Ocean Discovery Program Site U1476. Here we demonstrated that precession cycles governed precipitation from 7.4 to ~6.9 Ma and during the early Pliocene. From ~6.9 to 5.9 Ma, the precession and long eccentricity cycles drove the SAFM. The major Antarctic ice sheet expansion across this interval appear to influence the isotopic records of Orbulina universa imprinting its long-term variability signal as a response to the ocean and atmospheric reorganization. Precession cycles markedly weakened from 5.9 to 5.3 Ma, almost the same period when the Mediterranean Outflow Water ceased. These findings highlight important teleconnections among the SAFM, Mediterranean Sea, and other tropical regions.

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