Geochemistry of Oligocene Huagang Formation clastic rocks, Xihu Sag, the East China Sea Shelf Basin: Provenance, source weathering, and tectonic setting
Geochemistry of Oligocene Huagang Formation clastic rocks, Xihu Sag, the East China Sea Shelf Basin: Provenance, source weathering, and tectonic setting
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东海陆架盆地西湖凹陷渐新世花港组碎屑岩地球化学：物源、物源风化与构造背景
DOI：
10.1002/gj.2906
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发表时间：
2018
影响因子：
1.8
通讯作者：
Ji H
中科院分区：
文献类型：
--
作者：
Hao L;Wang Q;Tao H;Li X;Ma D;Ji H
东海陆架盆地是西太平洋活动大陆边缘的重要构造单元。它进一步分为一系列凹陷和基底脊。东海陆架盆地东缘西湖凹陷是重要的油气勘探区，蕴藏着重要的油气资源。花港组是西湖凹陷的主要储层，其物源一直是争论的焦点。分析了西湖凹陷渐新世花港组砂泥岩样品的常量和微量元素（包括稀土元素）组成。讨论了这些碎屑岩的物源和构造环境。化学蚀变指数值和A-CN-K图解显示花港组物源区风化程度为低-中度。泥岩的成分变异指数值较低（<1），表明泥岩样品成分成熟，而砂岩样品的成分变异指数值（0.59 ~ 1.87）表明砂岩成分未成熟和成熟。碎屑岩样品的常量和微量元素组成及比值表明，泥岩主要来自中国东南地区晚中生代火成岩，以酸性火山岩为主。砂岩的物源来自两个不同的方向，即东昆仑中央隆起群和以镁铁质火山岩为主的台湾-新资褶皱带。根据碎屑岩样品的地球化学分析，西湖凹陷渐新世花港组沉积时期的构造背景为日本型大陆边缘。
The East China Sea Shelf Basin (ECSSB) is an important tectonic unit of the western Pacific active continental margin. It is divided further into a series of sags and basement ridges. The Xihu Sag on the east margin of the ECSSB is an important hydrocarbon exploration area and contains significant petroleum resources. The Huagang Formation is the major reservoir in Xihu Sag, and its provenance has been the focus of debate at all times. The major and trace elements (including rare earth elements) compositions were analyzed for the Oligocene Huagang Formation sandstone and mudstone samples in the Xihu Sag. The provenance and tectonic setting of these clastic rocks are discussed. The Chemical Index of Alteration value and A–CN–K diagrams suggest low to moderate weathering in the source areas of the Huagang Formation. The mudstones have lower index of compositional variation values (<1), indicating that the mudstone samples are compositionally mature, whereas the index of compositional variation values for the sandstone samples (0.59 to 1.87) indicate that the sandstones are compositionally immature and mature. The major and trace element composition and ratios of the clastic rock samples indicate that mudstones are mainly from Late Mesozoic igneous rocks in SE China, which is dominated by the acidic volcanic rock. The provenance of sandstones is from two different directions, the Central Uplift Group of ECSSB and the Taiwan–Sinzi Fold Belt with more mafic volcanic rock. Based on the geochemical analysis of the clastic rock samples, the tectonic setting of Xihu Sag was Japanese‐type continental margin during the Huagang Formation deposition time (Oligocene).