Carbonate Platform Development and Sea-Level Variations of Xisha Islands:Based on BIT Index of Well Xike-1
Wang Zhenfeng
Cui Yuchi
Shao Lei
Zhang Daojun
Dong Xixi
Liu Xinyu
Zhang Chuanlun
You Li
Xiao Antao
Abstract：In order to explore the developmental process of carbonate platform in the South China Sea (SCS)and its control fac-tors,the organic molecular compound index method were described in this study.The branched isoprenoid tetraether (BIT )in-dex is the ratio between the branched glycerol dialkyl glycerol tetraethers (bGDGTs)from terrigenous supply and isoprenoid GDGTs (iGDGTs)from marine crenarchaeol comprising the majority of denominator,which serves as a proxy for provenance discrimination of the organic matter and related sedimentary environments in paleoenvironmental research.The BIT curve of well Xike-1 is characterized by a unique “high-low-high”feature up section,indicating the effects of sea-level variations and car-bonate platform development since Middle Miocene in the SCS.Strata with reef-beach facies were developed within carbonate platforms of Xisha Islands influenced by decrease in global as well as regional sea-level during the Late Miocene,with increased BIT values due to plenty of precipitation.Between Late Miocene and Pliocene when sea-level was higher,carbonate platforms were better formed in shallow marine environment with low BIT values.Carbonate platforms of Xisha Islands were periodically exposed in Quaternary as a result of sea-level decline over glacial cycles,leading to the second increase in BIT .Our results demonstrate that carbonate platforms of Xisha Islands have been affected by regional sea-level variations,reflecting a coupling effect on the SCS by global sea-level fluctuations and regional tectonic subductions.
Keywords：South China SeaXisha Islandswell Xike-1biohermorganic compoundmarine geologystratigraphy
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：9( 900-908 )