气候变化领域集成服务门户(CCPortal): Early Jurassic high-Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo-Tethyan Ocean

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DOI	10.1002/gj.3309
	Early Jurassic high-Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo-Tethyan Ocean
	Wang, Chao; Ding, Lin; Zhang, Li-Yun; Ding, Xiang-Li; Yue, Ya-Hui
通讯作者	Wang, C (通讯作者)
发表日期	2019
ISSN	0072-1050
EISSN	1099-1034
起始页码	2508
结束页码	2524
卷号	54 期号:4
英文摘要	Over the past few years, an increasing number of Early Jurassic magmatic rocks have been found in the southern Lhasa terrane and well studied; however, high-Mg andesitic rocks are considerably rare, and the Mesozoic palaeotectonic framework of Neo-Tethyan Ocean remains controversial. The present study focuses on Early Jurassic high-Mg andesites that outcropped in the Quxu area, southern Lhasa terrane. In the Quxu area, the Early Jurassic (189 Ma) volcanic sequences are mainly composed of andesites and basaltic andesites and are unconformably in contact with Late Triassic diorites (226 Ma). These volcanic rocks are characterized by SiO2 (49-58 wt.%), MgO (6.2-11.1 wt.%) and Mg# (61-69), TiO2 (0.48-0.76 wt.%) and TFeO/MgO ratios (0.80-1.13), with geochemical features similar to those of high-Mg andesites. Their depleted mantle-type Nd (epsilon(Nd)(t) = +4.9 to +6.9) and Hf (epsilon(Hf)(t) = +9.6 to +14.9) isotopic compositions, together with their geochemical characteristics, suggest that the Quxu high-Mg andesites were most likely produced by the interaction between the asthenospheric mantle and lithospheric mantle that metasomatized by slab-derived fluids. The diorites belong to metaluminous calc-alkaline series with highly positive epsilon(Hf)(t) values (+13.4 to +15.8) and are interpreted to be produced mainly by partial melting of the juvenile crustal basaltic rocks with minor input from the depleted mantle. We speculate that, in combination with the distribution of the Mesozoic magmatic rocks in the southern Lhasa terrane, the rollback of the subducting Neo-Tethyan Ocean was the prime reason for the Early Jurassic tectono-magmatic evolution in the southern Lhasa terrane. This process facilitated a rapid linear upwelling of the asthenospheric mantle beneath the southern Lhasa terrane and ultimately led to the large-scale magmatic flare-ups. Furthermore, events associated with slab rollback likely played an important role in crustal growth in the southern Lhasa terrane.
关键词	ZIRCON U-PB SETOUCHI VOLCANIC BELT HF ISOTOPE CONSTRAINTS TECTONIC EVOLUTION TRACE-ELEMENT GANGDESE BATHOLITH CONTINENTAL-CRUST HAFNIUM ISOTOPE NEO-TETHYS PALEOMAGNETIC CONSTRAINTS
英文关键词	high-Mg andesites; Lhasa terrane; Mesozoic magmatism; Neo-Tethyan Ocean; subduction
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:000477016000038
来源期刊	GEOLOGICAL JOURNAL
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259403
推荐引用方式 GB/T 7714	Wang, Chao,Ding, Lin,Zhang, Li-Yun,et al. Early Jurassic high-Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo-Tethyan Ocean[J]. 中国科学院青藏高原研究所,2019,54(4).
APA	Wang, Chao,Ding, Lin,Zhang, Li-Yun,Ding, Xiang-Li,&Yue, Ya-Hui.(2019).Early Jurassic high-Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo-Tethyan Ocean.GEOLOGICAL JOURNAL,54(4).
MLA	Wang, Chao,et al."Early Jurassic high-Mg andesites in the Quxu area, southern Lhasa terrane: Implications for magma evolution related to a slab rollback of the Neo-Tethyan Ocean".GEOLOGICAL JOURNAL 54.4(2019).