A ~12 Myr Miocene record of Asian Monsoon variability from the South China Sea

DOI

The long-term evolution of the Southeast Asian Monsoon and the processes controlling its variability under changing climate boundary conditions remain enigmatic. Here, we integrate high-resolution planktic and benthic foraminiferal isotope data with proxy records for chemical weathering derived from diffuse reflectance spectroscopy at Ocean Drilling Program Site 1146 (South China Sea) to reconstruct the evolution of the summer monsoon between ~17 and 5 Ma. Our records show that an overall warm and humid tropical climate prevailed over southeastern Asia during the Miocene Climatic Optimum, suggesting northward expansion of the tropical rain belt in response to greenhouse gas forcing. By contrast, monsoon seasonality increased during the middle Miocene Climatic Transition in tandem with Antarctic glacial expansion and global cooling. Substantial weakening or failure of the summer monsoon between ~12.7 and 10.9 Ma supports that decreased weathering and riverine input of nutrients and alkalinity contributed to carbonate depletion in the deep ocean during the Carbonate Crash. Intensification of monsoonal circulation and strengthening of the biological pump through the late Miocene promoted carbon burial, drawdown of atmospheric CO2 and climate cooling during the Biogenic Bloom. These results underscore the dynamic evolution of the Southeast Asian Monsoon throughout the middle to late Miocene. Variations in local insolation forcing and in Southern Hemisphere ice volume, influencing the latitudinal thermal gradient, evaporation-moisture budgets and the strength of the tropical convection, exerted major controls on the development of the monsoon.

Identifier
DOI https://doi.org/10.1594/PANGAEA.931111
Related Identifier https://doi.org/10.1029/2021PA004267
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.931111
Provenance
Creator Holbourn, Ann E ORCID logo; Kuhnt, Wolfgang; Clemens, Steven C ORCID logo; Heslop, David ORCID logo
Publisher PANGAEA
Publication Year 2021
Funding Reference German Research Foundation https://doi.org/10.13039/501100001659 Crossref Funder ID Ku649/30-1 ; German Research Foundation https://doi.org/10.13039/501100001659 Crossref Funder ID Ku649/31-1
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Language English
Resource Type Bundled Publication of Datasets; Collection
Format application/zip
Size 4 datasets
Discipline Earth System Research
Spatial Coverage (116.273W, 19.457S, 116.273E, 19.457N)
Temporal Coverage Begin 1999-03-21T00:00:00Z
Temporal Coverage End 1999-03-29T06:15:00Z