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DOI	10.1016/j.epsl.2021.116764
	Long-lived (ca. 22–24 Myr) partial melts in the eastern Himalaya: Petrochronologic constraints and tectonic implications
	Ding H.; Kohn M.J.; Zhang Z.
发表日期	2021
ISSN	0012821X
卷号	558
英文摘要	Partial melting is thought to profoundly impact the rheology and deformation behavior of the middle crust. Consequently, investigations of the pressure-temperature conditions of metamorphism, rates of heating, and durations of anatexis can provide unique constraints on tectonic processes. The Greater Himalayan Sequence (GHS), in the metamorphic core of the Himalayan orogen, is commonly considered to represent exhumed, anatectic, mid-crust. Here, we present detailed petrological and geochronological analysis of anatectic pelitic schist and felsic paragneiss from the uppermost structural level of the GHS to understand the timing and conditions of Himalayan anatexis. Petrologic analysis indicates that these rocks experienced high-grade metamorphism and partial melting up to peak conditions of ca. 720–745°C and ca. 9.6–10 kbar. Melt volumes of ca. 3% increased slightly during exhumation with nearly constant or slightly decreasing temperature, then decreased as rocks cooled, ultimate crossing the solidus at ca. 5.5 kbar and 700°C. Well-correlated U–Th–Pb ages and trace element data (HREE, Y, and Eu/Eu*) for monazite and zircon require prograde metamorphism and initial partial melting of GHS rocks at ca. 50 and 42–40 Ma, respectively, and crystallization of melts at ca. 24–18 Ma. These data indicate a long-lived (ca. 22–24 Myr) partially molten mid-crust in the eastern Himalayan orogen that formed as much as 10 Myr earlier and lasted 10 Myr longer than numerical models of viscous flow have predicted. Thermal buffering and melt stagnation may reflect feedbacks between thermal structure and shear stress. The change from thermal and mechanical stasis to rapid exhumation and cooling at ca. 24 Ma corresponds with an orogen-wide shift in deformation patterns, and may reflect arrival of mainland India. © 2021
关键词	anatexis Himalaya monazite petrochronology P–T path zircon
英文关键词	Deformation; Gasoline; Geochronology; Melting; Phosphate minerals; Shear stress; Silicate minerals; Trace elements; Zircon; Deformation behavior; Deformation pattern; High grade metamorphism; Pressure-temperature conditions; Structural levels; Tectonic implications; Thermal buffering; Thermal structure; Tectonics; deformation; fractional crystallization; geochronology; metamorphism; P-T conditions; P-T-t path; partial melting; petrology; tectonic evolution; India
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203073
作者单位	School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China; Department of Geosciences, Boise State University, Boise, ID 83725, United States; Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China
推荐引用方式 GB/T 7714	Ding H.,Kohn M.J.,Zhang Z.. Long-lived (ca. 22–24 Myr) partial melts in the eastern Himalaya: Petrochronologic constraints and tectonic implications[J],2021,558.
APA	Ding H.,Kohn M.J.,&Zhang Z..(2021).Long-lived (ca. 22–24 Myr) partial melts in the eastern Himalaya: Petrochronologic constraints and tectonic implications.Earth and Planetary Science Letters,558.
MLA	Ding H.,et al."Long-lived (ca. 22–24 Myr) partial melts in the eastern Himalaya: Petrochronologic constraints and tectonic implications".Earth and Planetary Science Letters 558(2021).