Ar-40/Ar-39 dating of oceanic plagiogranite: Constraints on the initiation of seafloor spreading in the South China Sea

CORC > 南海海洋研究所 > 中国科学院南海海洋研究所 > 中科院边缘海地质重点实验室

	Ar-40/Ar-39 dating of oceanic plagiogranite: Constraints on the initiation of seafloor spreading in the South China Sea
	Zhong, LF; Cai, GQ; Koppers, AAP; Xu, YG; Xu, HH; Gao, HF; Xia, B
刊名	LITHOS
	2018
卷号	302 页码:421-426
通讯作者	zhonglf9@mail.sysu.edu.cn ; caiguanqiang@sina.com
中文摘要	The Cenozoic opening of the South China Sea was one of the most significant tectonic events in SE Asia, coinciding with complex regional rifting, subduction, terrane collision, and large-scale continental strike-slip faulting. The timing of the initiation of seafloor spreading in the South China Sea remains controversial due to a scarcity of incontrovertible age data. This work provides the first report of an oceanic plagiogranite from the Penglai Sea-mount, located on the 17 degrees N fossil spreading center of the East Sub-basin of the South China Sea, near the Manila Trench. Pyroxene and whole-rock Ar-40/Ar-39 dating yields ages of 32.3 +/- 0.5 Ma and 28.9 +/- 1.9 Ma, respectively. The plagiogranite show trace element and isotopic composition similar to those of mid-oceanic ridge basalts (MORB), with Sr-87/Sr-86(t) = 0.70394; epsilon(Nd)(t) = 8.21; (206)pb/(204)pb = 17.9930, (207)pb/(204)pb = 15.4839, Pb-208/Pb-204 = 37.8852; epsilon(Hf)(t) = 20.95; and gamma(Os)(t) = 15.89. It suggested that the rock formed due to differential cooling between adjacent layers of oceanic crust and asthenospheric shearing at the oceanic spreading ridge, resulting in the development of detachment faults. This triggered the subsequent ingress of seawater along the faults, which transformed into a hydrothermal fluid under the influence of shear and geothermal heating, altering the parent gabbro, and leading to the generation of the daughter plagiogranite by anatexis during the early Oligocene. This new geochronology also demonstrates that the initial opening of the South China Sea occurred before 32 Ma, thereby constraining the Cenozoic tectonic evolution of Southeast Asia. (C) 2018 Elsevier B.V. All rights reserved.
学科主题	Geochemistry & Geophysics; Mineralogy
关键词[WOS]	Oceanic plagiogranite ; Ar-40/Ar-39 geochronology ; Petrogenesis ; Seafloor spreading ; South China Sea
内容类型	期刊论文
源URL	[http://ir.scsio.ac.cn/handle/344004/17148]
专题	南海海洋研究所_中科院边缘海地质重点实验室
推荐引用方式 GB/T 7714	Zhong, LF,Cai, GQ,Koppers, AAP,et al. Ar-40/Ar-39 dating of oceanic plagiogranite: Constraints on the initiation of seafloor spreading in the South China Sea[J]. LITHOS,2018,302:421-426.
APA	Zhong, LF.,Cai, GQ.,Koppers, AAP.,Xu, YG.,Xu, HH.,...&Xia, B.(2018).Ar-40/Ar-39 dating of oceanic plagiogranite: Constraints on the initiation of seafloor spreading in the South China Sea.LITHOS,302,421-426.
MLA	Zhong, LF,et al."Ar-40/Ar-39 dating of oceanic plagiogranite: Constraints on the initiation of seafloor spreading in the South China Sea".LITHOS 302(2018):421-426.