Grain size analysis and depositional pattern of sediments of IODP Site 1501 from the northern margin of the South China Sea: tectonic and climatic implications

Cukur, Deniz, Buchs, David M. ORCID: https://orcid.org/0000-0001-8866-8125, Kim, Gil Young, Horozal, Senay, Hong, Seok-Hwi and Kim, Seong-Pil 2025. Grain size analysis and depositional pattern of sediments of IODP Site 1501 from the northern margin of the South China Sea: tectonic and climatic implications. Journal of the Geological Society 10.1144/jgs2025-047 Item availability restricted.

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Abstract

Grain size analysis of the terrigenous fraction of sediments from IODP Site U1501 was used to characterize depositional patterns in the northern South China Sea since the middle Eocene (∼35 Ma). Fine sand dominates the lower sequence (∼457 to 440 m CSF-A), reflecting turbidite influence on the Chinese continental shelf (∼35-34 Ma). This is followed by a fining-upward trend (4 to 8 phi) marking transition to hemipelagic deposition mostly devoid of turbidites. A new silt-dominated sedimentation regime established at ∼30 Ma, which correlates to the initial expansion of the Pearl River. The regime is accompanied by stable source geochemical proxies (e.g., Zr/TiO 2 values) and remains unaffected by an unconformity (T60) and hiatus at ∼26.8–24.36 Ma. Grain size changes with stable geochemical proxies require variable intensities of terrigenous influx, that we propose reflect the dynamics of surface buoyant plumes and their controlling factors. At ∼16 Ma, sediment fines abruptly (4.7 to 7.5 phi) and grain size remains constant to present, reflecting drier conditions in the source area that began shortly afterward. Observed patterns suggest that grain size data from hemipelagic sediments devoid of turbidites can be combined with source tracers to help reconstruct the intensity of buoyant plumes over time.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Earth and Environmental Sciences
Publisher:	The Geological Society
ISSN:	0016-7649
Date of First Compliant Deposit:	16 July 2025
Date of Acceptance:	10 June 2025
Last Modified:	16 Jul 2025 08:30
URI:	https://orca.cardiff.ac.uk/id/eprint/179658

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