气候变化领域集成服务门户(CCPortal): Post-Collisional Silica-Undersaturated Bamaoqiongzong Volcanic Rocks from Northern Qiangtang: Indicators of the Mantle Heterogeneity and Geodynamic Evolution of Central Tibet

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DOI	10.1093/petrology/egac123
	Post-Collisional Silica-Undersaturated Bamaoqiongzong Volcanic Rocks from Northern Qiangtang: Indicators of the Mantle Heterogeneity and Geodynamic Evolution of Central Tibet
	Qi, Yue; Wang, Qiang; Wei, Gang-Jian; Wyman, Derek A.; Zhang, Xiu-Zheng; Dan, Wei; Zhang, Le; Yang, Ya-Nan
发表日期	2023
ISSN	0022-3530
EISSN	1460-2415
卷号	64 期号:1
英文摘要	The formation of post-collisional mantle-derived rocks in the Tibetan Plateau has been linked to the deep geodynamic processes that cause surface uplift. Co-existing silica-oversaturated to silica-undersaturated mantle-derived rocks have been identified in the northern Qiangtang Terrane (NQT). However, the origins of silica-undersaturated magmas are controversial, and the mechanisms responsible for variable silica activity in the mantle-derived rocks are unclear. Here, we present 40Ar/39Ar chronology, mineral chemistry, and whole-rock geochemical data for the Bamaoqiongzong (BMQZ) volcanic rocks of the NQT. The BMQZ volcanic rocks consist of olivine leucitites, trachybasalts, and phonolites and were erupted at ca. 29 Ma. All samples are unsaturated in silica and characterized by enrichment in light rare earth elements and large-ion lithophile elements, depletion in high-field-strength elements, and the presence of negative Nb-Ta-Ti anomalies and positive Pb anomalies. All samples show limited variation in (Sr-87/Sr-86)(i) (0.7079-0.7085) and epsilon(Nd)(t) values (-6.9 to -5.3). The geochemical compositions of the BMQZ volcanic rocks indicate that they were produced by partial melting of carbonated phlogopite-lherzolite within the lithospheric mantle. The formation of the olivine leucitites-trachybasalts-phonolites suite was controlled by fractional crystallization and magma mixing in a magmatic plumbing system. This plumbing system included several independent reservoirs and conduits within the crust. The enriched mantle sources of the BMQZ volcanic rocks were formed by the addition of carbonate-rich melts released from the southward-subducted Songpan-Ganzi Terrane after the Late Cretaceous. Our new results, together with published data, reveal systematic variations in geochemical compositions between silica-undersaturated and silica-oversaturated rocks in the NQT, which are ascribed to variations in the nature of the subducted continental materials added during intracontinental subduction. Carbonate-rich melts that were formed by the breakdown of carbonate minerals helped to generate the mantle sources of silica-undersaturated rocks, whereas silicate melts produced by the partial melting of sediment diapirs contributed to the generation of the silica-oversaturated rocks. On the basis of published numerical modelling of continental subduction and crustal deformation records in the NQT, we suggest that intracontinental subduction and lithospheric thinning together contributed to the generation of post-collisional mantle-derived rocks in the Tibetan Plateau.
关键词	mantle-derived rocks northern Tibet intracontinental subduction lithospheric thinning surface uplift
英文关键词	ULTRAPOTASSIC IGNEOUS ROCKS; HF ISOTOPIC CHARACTERISTICS; CENOZOIC BASIN EVOLUTION; TRIASSIC ARC MAGMATISM; SLAB-DERIVED MELTS; HOH XIL BASIN; U-PB AGES; TECTONIC EVOLUTION; CONTINENTAL-CRUST; EARLY UPLIFT
WOS研究方向	Geochemistry & Geophysics
WOS记录号	WOS:000913099800001
来源期刊	JOURNAL OF PETROLOGY
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283161
作者单位	Chinese Academy of Sciences; Guangzhou Institute of Geochemistry, CAS; Chinese Academy of Sciences; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; University of Sydney
推荐引用方式 GB/T 7714	Qi, Yue,Wang, Qiang,Wei, Gang-Jian,et al. Post-Collisional Silica-Undersaturated Bamaoqiongzong Volcanic Rocks from Northern Qiangtang: Indicators of the Mantle Heterogeneity and Geodynamic Evolution of Central Tibet[J],2023,64(1).
APA	Qi, Yue.,Wang, Qiang.,Wei, Gang-Jian.,Wyman, Derek A..,Zhang, Xiu-Zheng.,...&Yang, Ya-Nan.(2023).Post-Collisional Silica-Undersaturated Bamaoqiongzong Volcanic Rocks from Northern Qiangtang: Indicators of the Mantle Heterogeneity and Geodynamic Evolution of Central Tibet.JOURNAL OF PETROLOGY,64(1).
MLA	Qi, Yue,et al."Post-Collisional Silica-Undersaturated Bamaoqiongzong Volcanic Rocks from Northern Qiangtang: Indicators of the Mantle Heterogeneity and Geodynamic Evolution of Central Tibet".JOURNAL OF PETROLOGY 64.1(2023).