Regional detrital zircon record of the drainage sediments surrounding the South China Sea: Provenance signature and tectonic implications

Abstract

U–Pb geochronology of detrital zircon is a powerful proxy that has seen significant growth and led to breakthroughs in understanding the sedimentary process and tectonic evolution in the South China Sea and its adjacent source terranes. However, uncertainties remain in determining the provenance of sediments due to the lack of systematic age compositions of the surrounding eroding sources. Here we present a new zircon U–Pb geochronological dataset from major drainage systems in seven geological domains surrounding the South China Sea, including large and coastal rivers in the South China and Indochina blocks, as well as rivers on the islands of Hainan, Taiwan, Luzon, Palawan, and Borneo. This dataset, combined with published data, forms a comprehensive detrital zircon U–Pb geochronological and Hf isotopic database (n = 21,580) for fluvial systems discharging into the South China Sea. The results show that these detrital zircons, with ages ranging from the Archean to the Cenozoic, have two major age groups at 260–220 Ma and 130–80 Ma and subordinate age populations at 2600–2400 Ma, 1900–1700 Ma, 1000–600 Ma, 500–390 Ma, and 40–20 Ma, corresponding to the major tectono-magmatic events in East and Southeast Asia. Detailed comparisons reveal distinct age signatures for each drainage system correlated with the basement characteristics of river basins, indicating a heterogeneous zircon age distribution. The findings indicate that the surrounding terranes have a significantly different crustal evolution history, with juvenile crustal growth occurring in the East and Southeast Asian continent predominantly during 2600–2400 Ma, 1800–1500 Ma, and 1000–700 Ma, and on the island of Luzon during the Cenozoic. This study provides a detrital zircon record for drainage systems surrounding the South China Sea and presents a method for defining regional first-order strategies to characterize the provenance and crustal evolution of the source terranes. The integrated dataset provides a critical foundation for investigating regional sediment provenance and tectonic correlations in East and Southeast Asia.