Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?

doi:10.1093/petrology/egr061

	Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?
	Wang, Xuan-Ce 1,2,3,4; Li, Zheng-Xiang 1,2; Li, Xian-Hua 3; Li, Jie 5; Liu, Ying 5; Long, Wen-Guo 6; Zhou, Jin-Bo 6; Wang, Fei 3
刊名	JOURNAL OF PETROLOGY
	2012
卷号	53 期号:1 页码:177-233
关键词	Hainan Island South China Sea basalts plume Cenozoic geochemistry
ISSN号	0022-3530
DOI	10.1093/petrology/egr061
文献子类	Article
英文摘要	Basaltic lavas from Hainan Island near the northern edge of the South China Sea have an age range of between late Miocene (about 13 Ma) and Holocene, with a peak age of late Pliocene to middle Pleistocene. The basaltic province is dominated by tholeiites with subordinate alkali basalts. Most analysed samples display light rare earth element (LREE) enriched REE patterns and ocean island basalt (OIB)-like incompatible element distributions. The basalts contain abundant undeformed high-Mg olivine phenocrysts (up to Fo(90.7)) that are high in CaO and MnO, indicating high-magnesian parental magmas. Independent barometers indicate that clinopyroxenes in the basalts crystallized over a wide range of pressures of 2-25 kbar (dominantly at 10-15 kbar) and that the melt cooled from about 1350 degrees C to 1100 degrees C during their crystallization. The compositional characteristics of the basalts indicate that their generation most probably involved both low-silica and high-silica melts, as represented by the alkali basalts and tholeiites, respectively. Our results show that the source region for the Hainan basalts is highly heterogeneous. The source for the tholeiites is mainly composed of peridotite and recycled oceanic crust, whereas the source for the bulk of the low-Th alkali basalts consists predominantly of peridotite and low-silica eclogite (garnet pyroxenite). Some high-Th (>= 4 ppm) alkali basalts may have been produced by partial melting of low-silica garnet pyroxenite (eclogite). We estimated the primary melt compositions for the Hainan basalts using the most forsteritic olivine (Fo(90.7)) composition and the most primitive bulk-rock samples (MgO > 9.0 wt % and CaO > 8.0 wt %), assuming a constant Fe-Mg exchange partition coefficient of K-D = 0.31 and Fe3+/Fe-T = 0.1. The effective melting pressure (P-f) and melting temperature (T) of the primary melts are P-f = 18-32 kbar (weighted average = 23.8 +/- 1.8 kbar) and T = 1420-1520 degrees C for the tholeiites, and P-f = 25-32 (weighted average = 28.3 +/- 1.4 kbar) and T = 1480-1530 degrees C for the alkali basalts. The P-f - T data form an array that plots systematically above the dry lherzolite solidus but below the base of the lithosphere (similar to 55 km) and intersects the dry peridotite solidus at a pressure of about 50 kbar. The mantle potential temperature beneath Hainan Island, based on the estimate primary melt compositions, varies from about 1500 to 1580 degrees C with a weighted average of 1541 +/- 10 degrees C. The high-magnesian olivine phenocrysts, high mantle potential temperature, and the presence of recycled oceanic crust in the source region provide independent support for the Hainan plume model that has previously been proposed largely based on geophysical observations. The Hainan plume thus provides a rare example of a young mantle plume associated with deep slab subduction.
WOS关键词	SOUTH CHINA SEA ; CRYSTAL-CHEMICAL CONTROLS ; WAVE VELOCITY STRUCTURE ; TRACE-ELEMENT ; PARTITION-COEFFICIENTS ; LHERZOLITE SOLIDUS ; MAFIC LITHOLOGIES ; LIQUID EQUILIBRIA ; GARNET PYROXENITE ; OXYGEN FUGACITY
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	OXFORD UNIV PRESS
WOS记录号	WOS:000299347800008
资助机构	National Natural Science foundation of China(40803010 ; National Natural Science foundation of China(40803010 ; Australian Research Council (ARC)(DP0770228) ; Australian Research Council (ARC)(DP0770228) ; 40973044) ; 40973044) ; National Natural Science foundation of China(40803010 ; National Natural Science foundation of China(40803010 ; Australian Research Council (ARC)(DP0770228) ; Australian Research Council (ARC)(DP0770228) ; 40973044) ; 40973044) ; National Natural Science foundation of China(40803010 ; National Natural Science foundation of China(40803010 ; Australian Research Council (ARC)(DP0770228) ; Australian Research Council (ARC)(DP0770228) ; 40973044) ; 40973044) ; National Natural Science foundation of China(40803010 ; National Natural Science foundation of China(40803010 ; Australian Research Council (ARC)(DP0770228) ; Australian Research Council (ARC)(DP0770228) ; 40973044) ; 40973044)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/84338]
专题	中国科学院地质与地球物理研究所
通讯作者	Wang, Xuan-Ce
作者单位	1.Curtin Univ, Dept Appl Geol, ARC Ctr Excellence Core Crust Fluid Syst CCFS, Perth, WA 6845, Australia 2.Curtin Univ, Inst Geosci Res TIGER, Perth, WA 6845, Australia 3.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithopher Evolut, Beijing 100029, Peoples R China 4.Univ Western Australia, Sch Earth & Environm, Crawley, WA 6009, Australia 5.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou 510640, Guangdong, Peoples R China 6.Hainan Inst Geol Survey, Haikou 570226, Peoples R China
推荐引用方式 GB/T 7714	Wang, Xuan-Ce,Li, Zheng-Xiang,Li, Xian-Hua,et al. Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?[J]. JOURNAL OF PETROLOGY,2012,53(1):177-233.
APA	Wang, Xuan-Ce.,Li, Zheng-Xiang.,Li, Xian-Hua.,Li, Jie.,Liu, Ying.,...&Wang, Fei.(2012).Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?.JOURNAL OF PETROLOGY,53(1),177-233.
MLA	Wang, Xuan-Ce,et al."Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?".JOURNAL OF PETROLOGY 53.1(2012):177-233.