气候变化领域集成服务门户(CCPortal): Coexistence of MORB- and OIB-like dolerite intrusions in the Purang ultramafic massif, SW Tibet: A paradigm of plume-influenced MOR-type magmatism prior to subduction initiation in the Neo-Tethyan lithospheric mantle

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DOI	10.1130/B35005.1
	Coexistence of MORB- and OIB-like dolerite intrusions in the Purang ultramafic massif, SW Tibet: A paradigm of plume-influenced MOR-type magmatism prior to subduction initiation in the Neo-Tethyan lithospheric mantle
	Zheng H.; Huang Q.; Kapsiotis A.; Lenaz D.; Velicogna M.; Xu C.; Cheng C.; Xia B.; Liu W.; Xiao Y.; Yang P.
发表日期	2019
ISSN	167606
起始页码	1276
结束页码	1294
卷号	131 期号:2021-07-08
英文摘要	The Yarlung Zangbo Suture Zone (YZSZ) of South Tibet is divided by the Zhongba- Zhada terrane into two subparallel ophiolitic belts in its western end. The peridotite massifs of the southern belt tectonically overlie the Tethyan Himalaya sequence. The Purang peridotite body in this belt is intruded by two groups of dolerite dikes, providing significant compositional, geochronological, and isotopic information about the melting history of the Neo-Tethyan mantle. U-Pb ages of zircons separated from dolerites show that peridotites of West Purang were intruded by an early generation of dikes at 138.5 ± 2.0 Ma (Valanginian). These dolerites show ocean island basalt (OIB)-type normalized multi-elemental profiles and Sr-Nd isotopic signatures [(La/Yb)N = 13-16], high initial 87Sr/86Sr ratios (0.70598-0.70765), and low εNd(t) values (-2.6 to -2.3). Zircons separated from this group of dolerites have slightly radiogenic εHf(t) values (+2.6 to +4.6). The next generation of dolerite dikes intruded the East Purang peridotites between 124.5 ± 2.5 Ma and 124.4 ± 3.2 Ma (Aptian). These East Purang dolerites show normal mid-ocean ridge basalt (N-MORB)- type normalized multi-element patterns [(La/Yb)N = 0.6-0.9] with noticeable negative Nb and Th (±Ti) anomalies, and have high 87Sr/86Sr(i) (0.70295-0.70618) and high εNd(t) values (+7.7 to +9.2). Zircons separated from the East Purang dolerites show strongly radiogenic εHf(t) values (+3.5 to +17.0). Semiquantitative geochemical modeling demonstrates that the parental magmas of West Purang dolerites were generated from 5%-10% polybaric partial melting of a deep-seated juvenile asthenospheric source enriched by plume-type components. In contrast, the parental melts of East Purang dolerites were derived from more than 20% melting of a juvenile spinel-bearing MORBtype mantle source that was modified by subduction-related melts/fluids to a minor extent. A possible tectono-magmatic model for the petrogenesis of the Purang ophiolitic massif could be linked to incipient continental rifting and subsequent oceanic seafloor spreading associated with decompression upwelling of an asthenospheric source contaminated by plume-type components. This plume-proximal seafloor spreading-system was succeeded by the initiation of Neo- Tethyan intra-oceanic subduction close to the active continental margin of Eurasia during the Early Cretaceous. © 2019 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184950
作者单位	Key Laboratory of Offshore Oil Exploration and Development of Guangdong Higher Education Institutes, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Science, Sun Yat-sen University, Guangzhou, 510275, China; Department of Mathematics and Geosciences, University of Trieste, Via Weiss 8, Trieste, 34128, Italy; School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
推荐引用方式 GB/T 7714	Zheng H.,Huang Q.,Kapsiotis A.,et al. Coexistence of MORB- and OIB-like dolerite intrusions in the Purang ultramafic massif, SW Tibet: A paradigm of plume-influenced MOR-type magmatism prior to subduction initiation in the Neo-Tethyan lithospheric mantle[J],2019,131(2021-07-08).
APA	Zheng H..,Huang Q..,Kapsiotis A..,Lenaz D..,Velicogna M..,...&Yang P..(2019).Coexistence of MORB- and OIB-like dolerite intrusions in the Purang ultramafic massif, SW Tibet: A paradigm of plume-influenced MOR-type magmatism prior to subduction initiation in the Neo-Tethyan lithospheric mantle.Bulletin of the Geological Society of America,131(2021-07-08).
MLA	Zheng H.,et al."Coexistence of MORB- and OIB-like dolerite intrusions in the Purang ultramafic massif, SW Tibet: A paradigm of plume-influenced MOR-type magmatism prior to subduction initiation in the Neo-Tethyan lithospheric mantle".Bulletin of the Geological Society of America 131.2021-07-08(2019).