Data

Pacific inflow into South China Sea related to post-rift opening of Luzon gateway: consequences for the East Asian monsoon

University of Tasmania, Australia

Sauermilch, Isabel

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ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=info:doi10.25959/5MCP-9G14&rft.title=Pacific inflow into South China Sea related to post-rift opening of Luzon gateway: consequences for the East Asian monsoon&rft.identifier=10.25959/5MCP-9G14&rft.description=The South China Sea (SCS) is the most important source of water vapor for the East Asian monsoon (EAM). Late Cenozoic (~34–30 Ma) opening of the SCS likely contributed significantly to the establishment of a strong, modern-like EAM at ~25 Ma per climate sensitivity studies. However, the importance of SCS tectonics in contributing to the evolution of the EAM has been neglected due to the temporal mismatch between both events (5–9 million years). Here, we investigate the bathymetric, sedimentary and oceanographic evolution of the SCS basin by combining Sr-Nd isotopic analyses of rift- to drift sediments from recent ocean drilling expeditions, high-resolution paleobathymetry reconstructions and ocean circulation simulations of this crucial time period. We show that the transition from fluvial, to shallow- and deep-marine environment in the SCS and its opening to the Pacific Ocean occurred well after the onset of seafloor spreading. We highlight a rapid (Maintenance and Update Frequency: notPlannedStatement: Samples from U1499 sediments across the pre-, syn- and post-rift transition were separated for detrital and authigenic fractions and analyzed for Nd and Sr isotopic ratios by solution MC-ICP-MS at the Center for Elemental Mass Spectrometry (University of South Carolina; see data repository, DR). The paleobathymetry of the SCS basin was reconstructed for two time slices covering the early opening phase (30 Ma and 25 Ma). The reconstruction uses the sediment backstripping method (Steckler and Watts, 1978) with newly available sediment thickness grids from seismic data across the SCS (Yin et al., 2020; details, see DR) and new constraints from drilling for thermal subsidence (Larsen et al., 2018a; Nirrengarten et al., 2020). These bathymetry grids are implemented in a high-resolution (0.1°) ocean model to simulate the consequences of the SCS opening on the ocean circulation pattern. The model uses MITgcm with surface forcing from a coupled global climate model (Hutchinson et al., 2018; details, see DR). Particle tracing is added to simulate the flow pattern between Pacific and SCS waters.&rft.creator=Sauermilch, Isabel &rft.date=2021&rft.coverage=westlimit=95.5933233564; southlimit=1.04421099798; eastlimit=129.167542106; northlimit=26.1823493809&rft.coverage=westlimit=95.5933233564; southlimit=1.04421099798; eastlimit=129.167542106; northlimit=26.1823493809&rft_rights=Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/&rft_rights=Cite data as: Sauermilch, I. (2021) Pacific inflow into South China Sea related to post-rift opening of Luzon gateway: consequences for the East Asian monsoon. Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS). doi:10.25959/5MCP-9G14&rft_rights=The data described in this record are the intellectual property of the University of Tasmania through the Institute for Marine and Antarctic Studies.&rft_subject=geoscientificInformation&rft_subject=EARTH SCIENCE | LAND SURFACE | GEOMORPHIC LANDFORMS/PROCESSES | AEOLIAN PROCESSES | SEDIMENTATION&rft_subject=EARTH SCIENCE | LAND SURFACE | GEOMORPHIC LANDFORMS/PROCESSES | TECTONIC PROCESSES&rft_subject=EARTH SCIENCE | CLIMATE INDICATORS | ATMOSPHERIC/OCEAN INDICATORS | EXTREME WEATHER | MONSOON ONSET/INTENSITY&rft_subject=Palaeoclimatology&rft_subject=EARTH SCIENCES&rft_subject=PHYSICAL GEOGRAPHY AND ENVIRONMENTAL GEOSCIENCE&rft_subject=Marine Geoscience&rft_subject=GEOLOGY&rft.type=dataset&rft.language=English Access the data

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Creative Commons Attribution 4.0 International License
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Cite data as: Sauermilch, I. (2021) Pacific inflow into South China Sea related to post-rift opening of Luzon gateway: consequences for the East Asian monsoon. Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS). doi:10.25959/5MCP-9G14

The data described in this record are the intellectual property of the University of Tasmania through the Institute for Marine and Antarctic Studies.

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The South China Sea (SCS) is the most important source of water vapor for the East Asian monsoon (EAM). Late Cenozoic (~34–30 Ma) opening of the SCS likely contributed significantly to the establishment of a strong, modern-like EAM at ~25 Ma per climate sensitivity studies. However, the importance of SCS tectonics in contributing to the evolution of the EAM has been neglected due to the temporal mismatch between both events (5–9 million years). Here, we investigate the bathymetric, sedimentary and oceanographic evolution of the SCS basin by combining Sr-Nd isotopic analyses of rift- to drift sediments from recent ocean drilling expeditions, high-resolution paleobathymetry reconstructions and ocean circulation simulations of this crucial time period. We show that the transition from fluvial, to shallow- and deep-marine environment in the SCS and its opening to the Pacific Ocean occurred well after the onset of seafloor spreading. We highlight a rapid (<1 myr), “flooding” event of Pacific bottom waters entering the young SCS through the narrow Luzon Strait between 25.5–24.5 Ma, coinciding with the strengthening EAM pattern. This shift is underscored by isotopic analysis of detrital fractions which suggest a change in provenance from local sources to inland China deserts and Loess signal shortly before ~25.5 Ma, likely transported as eolian dust by intensifying winter monsoon winds. Tectonic-driven rapid Pacific flooding likely increased the east-west humidity gradient between land and sea and contributed to the establishment of a modern-like, strong EAM at 25 Ma.

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Maintenance and Update Frequency: notPlanned

Statement: Samples from U1499 sediments across the pre-, syn- and post-rift transition were separated for detrital and authigenic fractions and analyzed for Nd and Sr isotopic ratios by solution MC-ICP-MS at the Center for Elemental Mass Spectrometry (University of South Carolina; see data repository, DR). The paleobathymetry of the SCS basin was reconstructed for two time slices covering the early opening phase (30 Ma and 25 Ma). The reconstruction uses the sediment backstripping method (Steckler and Watts, 1978) with newly available sediment thickness grids from seismic data across the SCS (Yin et al., 2020; details, see DR) and new constraints from drilling for thermal subsidence (Larsen et al., 2018a; Nirrengarten et al., 2020). These bathymetry grids are implemented in a high-resolution (0.1°) ocean model to simulate the consequences of the SCS opening on the ocean circulation pattern. The model uses MITgcm with surface forcing from a coupled global climate model (Hutchinson et al., 2018; details, see DR). Particle tracing is added to simulate the flow pattern between Pacific and SCS waters.

Notes

Credit
LE160100067

Credit
Discovery Project 180102280

Credit
P2LAP2_171819

Data time period: 2021-03-23 to 2050-03-23

This dataset is part of a larger collection

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text: westlimit=95.5933233564; southlimit=1.04421099798; eastlimit=129.167542106; northlimit=26.1823493809

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uri : https://thredds.imas.utas.edu.au/thredds/catalog/IMAS/ISauermilch_Pacific_Inflow/catalog.html External Link

Identifiers

DOI : 10.25959/5MCP-9G14
global : 31b47b74-2ef2-4552-8c44-a87b18891388