Late Cretaceous back-arc extension and arc system evolution in the Gangdese area, southern Tibet: Geochronological, petrological, and Sr-Nd-Hf-O isotopic evidence from Dagze diabases

doi:10.1002/2015JB011966

CORC > 地质与地球物理研究所 > 中国科学院地质与地球物理研究所 > 岩石圈演化国家重点实验室

	Late Cretaceous back-arc extension and arc system evolution in the Gangdese area, southern Tibet: Geochronological, petrological, and Sr-Nd-Hf-O isotopic evidence from Dagze diabases
	Ma, Lin 1,2; Wang, Qiang 1,2; Wyman, Derek A.3; Jiang, Zi-Qi 1; Wu, Fu-Yuan 4; Li, Xian-Hua 4; Yang, Jin-Hui 4; Gou, Guo-Ning 1; Guo, Hai-Feng 1
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
	2015-09-01
卷号	120 期号:9 页码:6159-6181
关键词	mafic rocks back-arc expansion rollback southern Tibet
DOI	10.1002/2015JB011966
文献子类	Article
英文摘要	Back-arc extension and asthenosphere upwelling associated with oceanic lithospheric subduction affect the structure and thermal regime of the arc lithosphere, which often triggers widespread extension-related mafic magmatism. Although it is commonly accepted that the Neo-Tethyan oceanic lithosphere subducted beneath the southern Lhasa block, resulting in the well-known Late Mesozoic Gangdese magmatic arc, the possible role of contemporary back-arc extension and asthenosphere upwelling has been disputed due to a lack of evidence for extension-related mafic magmatism. Here, we report detailed petrological, geochronological, geochemical, and Sr-Nd-Hf-O isotopic data for the Dagze diabases located in the north of the Gangdese district, southern Lhasa block. The zircon U-Pb analyses indicate that they were generated in the Late Cretaceous (ca. 92Ma) instead of the Eocene (42-38Ma) as previously believed. These mafic rocks are characterized by variable MgO (4.0-12.2wt %) and Mg-# (42 to 71) values combined with flat to slightly enriched ([La/Yb](N)=1.87-5.23) light rare earth elements (REEs) and relative flat heavy REEs ([Gd/Yb](N)=1.36-1.87) with negative Ta, Nb, and Ti anomalies (e.g., [Nb/La](PM)=0.16-0.51). They also have slightly variable epsilon(Nd)(t) (-1.25 to +4.71) and low initial Sr-87/Sr-86 (0.7045-0.7058) values with strong positive igneous zircon epsilon(Hf)(t) (+8.0 to +12.1) and low O-18 (5.31-6.12) values. The estimated primary melt compositions are similar to peridotite-derived experimental melts. Given their high melting temperature (1332 to 1372 degrees C) and hybrid geochemical characteristics, we propose that the Dagze mafic magmas likely represent mixtures of asthenospheric and enriched lithospheric mantle-derived melts that underwent minor crustal assimilation and fractional crystallization of clinopyroxene. Taking into account the spatial and temporal distribution of Mesozoic mafic-felsic magmatic rocks and regional paleomagnetic and basin data, we suggest that the Dagze mafic rocks resulted from asthenospheric upwelling associated with intracontinental back-arc extension during the rollback of subducted Tethyan oceanic lithosphere in the Late Cretaceous.
WOS关键词	ZIRCON U-PB ; MIDOCEAN RIDGE SUBDUCTION ; NORTHERN MARIANA TROUGH ; INDO-ASIAN COLLISION ; ADAKITE-LIKE ROCKS ; VOLCANIC-ROCKS ; LHASA TERRANE ; DEPLETED MANTLE ; SLAB WINDOW ; TECTONIC IMPLICATIONS
WOS研究方向	Geochemistry & Geophysics
语种	英语
WOS记录号	WOS:000363420000012
资助机构	Chinese Academy of Sciences(XDB03010600) ; Chinese Academy of Sciences(XDB03010600) ; National Natural Science Foundation of China(41402048 ; National Natural Science Foundation of China(41402048 ; Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS 135 project)(Y234021001) ; Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS 135 project)(Y234021001) ; 41025006 ; 41025006 ; 41421062 ; 41421062 ; 41303017) ; 41303017) ; Chinese Academy of Sciences(XDB03010600) ; Chinese Academy of Sciences(XDB03010600) ; National Natural Science Foundation of China(41402048 ; National Natural Science Foundation of China(41402048 ; Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS 135 project)(Y234021001) ; Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS 135 project)(Y234021001) ; 41025006 ; 41025006 ; 41421062 ; 41421062 ; 41303017) ; 41303017)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/62201]
专题	地质与地球物理研究所_岩石圈演化国家重点实验室
作者单位	1.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Isotope Geochem, Guangzhou, Guangdong, Peoples R China 2.CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing, Peoples R China 3.Univ Sydney, Sch Geosci, Sydney, NSW 2006, Australia 4.Chinese Acad Sci, Inst Geol & Geophys, Beijing, Peoples R China
推荐引用方式 GB/T 7714	Ma, Lin,Wang, Qiang,Wyman, Derek A.,et al. Late Cretaceous back-arc extension and arc system evolution in the Gangdese area, southern Tibet: Geochronological, petrological, and Sr-Nd-Hf-O isotopic evidence from Dagze diabases[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2015,120(9):6159-6181.
APA	Ma, Lin.,Wang, Qiang.,Wyman, Derek A..,Jiang, Zi-Qi.,Wu, Fu-Yuan.,...&Guo, Hai-Feng.(2015).Late Cretaceous back-arc extension and arc system evolution in the Gangdese area, southern Tibet: Geochronological, petrological, and Sr-Nd-Hf-O isotopic evidence from Dagze diabases.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,120(9),6159-6181.
MLA	Ma, Lin,et al."Late Cretaceous back-arc extension and arc system evolution in the Gangdese area, southern Tibet: Geochronological, petrological, and Sr-Nd-Hf-O isotopic evidence from Dagze diabases".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 120.9(2015):6159-6181.