The delamination of lower crust in continental back-arc basin: Evidence from Sr isotope and elemental compositions of plagioclase and clinopyroxene in andesites from Kueishantao, north of Taiwan, China

doi:10.1016/j.lithos.2022.106653

CORC > 海洋研究所 > 中国科学院海洋研究所 > 海洋地质与环境重点实验室

	The delamination of lower crust in continental back-arc basin: Evidence from Sr isotope and elemental compositions of plagioclase and clinopyroxene in andesites from Kueishantao, north of Taiwan, China
	Guo, Kun 1,2,5,6; Wang, Xiaoyuan 6,7; Chen, Shuai 6,7; Shang, Luning 3,7; Liu, Bingquan 4; Zhang, Xia 2,7; Lai, Zhiqing 1,5
刊名	LITHOS
	2022-05-01
卷号	416 页码:19
关键词	Plagioclase Clinopyroxene Delamination Subduction Back-arc
ISSN号	0024-4937
DOI	10.1016/j.lithos.2022.106653
通讯作者	Wang, Xiaoyuan(wangxiaoyuan@qdio.ac.cn) ; Lai, Zhiqing(laizhiqing@ouc.edu.cn)
英文摘要	Subduction zones (arcs and back-arcs) are major sites for elemental cycling via slab dehydration and subsequent mantle metasomatism and melting; many models have been suggested by researchers to explain these processes. However, the influence of the overriding lithosphere, especially the lower crust, on the generation of back-arc magmas during the early spreading stage remains largely unknown. Kueishantao (KST), located at the tectonic junction of the southernmost part of the Okinawa Trough (SPOT) and the Ryukyu arc, is an ideal setting to investigate these issues because of the obvious differences between the subducted slab and the overriding continental lithosphere. To better address the contribution of the overriding lithosphere to a nascent back-arc basin, we examined the in situ major and trace element compositions of plagioclase (Pl) and clinopyroxene (Cpx) phenocrysts and the in situ Sr-87/Sr-86 of Pl phenocrysts in andesites from KST.& nbsp;The Pl and Cpx in KST andesites show obvious evolution (An contents of Pl, 39-91; Mg-# of Cpx, 73-92). The valid thermobarometers of Pl and Cpx imply crystallization temperatures and depths of 1059-1117 & nbsp;C and 1-14 km, respectively, similar to those of the SPOT. The compositions of Cpx suggest that the KST andesitic magma belonged to the subalkaline, tholeiitic and calc-alkaline magma series. The delta Eu values of Pl are 9.27-25.73, and those of Cpx are 0.50-0.92, indicating that the magma experienced Pl crystallization and separation. The Sr-87/Sr-86 values of Pl range from 0.705630 to 0.706985 and remain constant with varying An contents (52-85), indicating an enriched magma source not resulting from assimilation of continental crust. Taking into consideration all geochemical, trace elemental, Sr-87/Sr-86 isotope and geophysical constraints, the principal magma source of KST andesites was probably the lower continental crust, which foundered into the convecting mantle and subsequently melted and interacted with asthenospheric mantle materials. The over-thickened crust, mantle corner flow and addition of subducted fluids in the KST area led to delamination. The structure and geochemistry of Pl and Cpx imply a simple two-or multilayer magma chamber system in the continental crust and a mixing magma process between a relatively silicic magma (H2O-saturated and high fO(2)) and a primitive mafic magma at shallow depths.
资助项目	Strategic Priority Research Program (B) of Chinese Academy of Sciences[XDB42020402] ; Shandong Provincial Natural Science Foundation, China[ZR2019BD010] ; Shandong Provincial Natural Science Foundation, China[ZR2020MD068] ; Open Fund of the Key Laboratory of Marine Geology and Environment, Chinese Academy of Sciences[MGE2021KG01] ; Open Fund of the Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology[MMRKF201807] ; Key Laboratory Submarine Geoscience and Prospecting Techniques, Minis-try of Education, Ocean university of China
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	ELSEVIER
WOS记录号	WOS:000799251500001
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/179272]
专题	海洋研究所_海洋地质与环境重点实验室
通讯作者	Wang, Xiaoyuan; Lai, Zhiqing
作者单位	1.Ocean Univ China, Coll Marine Geosci, Qingdao 266100, Peoples R China 2.Pilot Natl Lab Marine Sci & Technol Qingdao, Ctr Isotope Geochem & Geochronol, Qingdao 266237, Peoples R China 3.China Geol Survey, Qingdao Inst Marine Geol, Qingdao 266071, Peoples R China 4.Geol Survey Jiangxi Prov, Nanchang 330030, Peoples R China 5.Ocean Univ China, Key Lab Submarine Geosci & Prospecting Tech, MOE, Qingdao 266100, Peoples R China 6.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China 7.Pilot Natl Lab Marine Sci & Technol Qingdao, Lab Marine Mineral Resources, Qingdao 266237, Peoples R China
推荐引用方式 GB/T 7714	Guo, Kun,Wang, Xiaoyuan,Chen, Shuai,et al. The delamination of lower crust in continental back-arc basin: Evidence from Sr isotope and elemental compositions of plagioclase and clinopyroxene in andesites from Kueishantao, north of Taiwan, China[J]. LITHOS,2022,416:19.
APA	Guo, Kun.,Wang, Xiaoyuan.,Chen, Shuai.,Shang, Luning.,Liu, Bingquan.,...&Lai, Zhiqing.(2022).The delamination of lower crust in continental back-arc basin: Evidence from Sr isotope and elemental compositions of plagioclase and clinopyroxene in andesites from Kueishantao, north of Taiwan, China.LITHOS,416,19.
MLA	Guo, Kun,et al."The delamination of lower crust in continental back-arc basin: Evidence from Sr isotope and elemental compositions of plagioclase and clinopyroxene in andesites from Kueishantao, north of Taiwan, China".LITHOS 416(2022):19.