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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; zhonglf9@mail.sysu.edu.cn; caiguanqiang@sina.com
2018
Source PublicationLITHOS
Volume302Pages:421-426
AbstractThe 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.
Department[Zhong, Li-Feng; Xia, Bin] Sun Yat Sen Univ, Sch Marine Sci, Coll Stn, 132 Waihuan Dong Rd, Guangzhou 510006, Guangdong, Peoples R China; [Cai, Guan-Qiang; Gao, Hong-Fang] Guangzhou Marine Geol Survey, Guangzhou, Guangdong, Peoples R China; [Koppers, Anthony A. P.] Oregon State Univ, Coll Earth Ocean & Atmospher Sci, Corvallis, OR 97331 USA; [Xu, Yi-Gang] Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China; [Xu, He-Hua] Chinese Acad Sci, South China Sea Inst Oceanol, Key Lab Ocean & Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China
Subject AreaGeochemistry & Geophysics ; Mineralogy
WOS KeywordOceanic plagiogranite ; Ar-40/Ar-39 geochronology ; Petrogenesis ; Seafloor spreading ; South China Sea
Funding ProjectMSG
Document Type期刊论文
Identifierhttp://ir.scsio.ac.cn/handle/344004/17148
Collection中科院边缘海地质重点实验室
Corresponding Authorzhonglf9@mail.sysu.edu.cn; caiguanqiang@sina.com
Recommended Citation
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.,...&caiguanqiang@sina.com.(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.
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