气候变化领域集成服务门户(CCPortal): Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau

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DOI	10.1016/j.epsl.2023.118316
	Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau
	Sheng, Yue; Jin, Sheng; Comeau, Matthew J.; Hou, Zengqian; Becken, Michael; Dong, Hao; Zhang, Letian; Wei, Wenbo; Ye, Gaofeng
发表日期	2023
ISSN	0012-821X
EISSN	1385-013X
卷号	619
英文摘要	Both low resistivity zones and low velocity zones are distributed in the middle-lower crust of the western Lhasa terrane, Tibetan Plateau, China. Some estimates from electrical resistivity data suggest large volume fractions of silicate melts that are difficult to reconcile with seismic velocity data that prefer lower volumes. A second conductive phase, such as saline fluids, that drastically reduces the conductivity but does not significantly affect the seismic velocity because of its low volume may be able to explain these differences. In this study, a 3-D model of the electrical resistivity structure is generated on a profile along longitude 85 & DEG;E from a latitude of 29 & DEG;N to 32.5 & DEG;N. Based on experimental measurement of melts and alkali-rich fluids (e.g., H2O-NaCl), we estimate the volume fraction of each phase that is required to explain the conductive anomalies observed in the geophysical model. The model reveals that the maximum bulk conductivity of the mid-lower crust in the south (1.52 S/m) is much higher than the conductivity of the mid-lower crust in the north (0.18 S/m) when taking 31 & DEG;N as a rough boundary, near Coqen region. We hypothesize that the conductive zones in the south of the Coqen region may result from a silicate melt and alkali-rich fluid (multicomponent) system. In contrast, partial melting alone can explain the conductive zones in the north. The hypothesis can reconcile the predictions from electrical resistivity data and seismic data, and it corresponds well with zircon Hf isotope data. For example, a combination such as the presence of <1% NaCl-bearing aqueous fluids in addition to 5-10% partial melt can reconcile electrical conductivity data and seismic data. We propose that the contributions from partial melt or saline fluids are controlled by the distinct tectonic dynamics in each region. Furthermore, the model compatible with the idea that the Indian lower crust subducted northwards beneath the Lhasa terrane and may not extend far beyond the Indus-Yarlung Zangbo suture (approximately 30-31 & DEG;N). The widespread distribution and interconnection of crustal conductors at different depths is consistent with the lateral migration of materials. However, both geophysical data sets agree that some anomalies are discontinuous along the profile. Furthermore, the low-angle subducted Indian Plate with no obvious tearing feature and a low volume of melts may have contributed to the absence of long, continuous, N-S-trending normal faults in this region.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/).
关键词	Lhasa terrane electrical conductivity melt fraction alkali-rich fluid Indian Plate
英文关键词	SOUTHERN TIBET; BENEATH; HIMALAYA; CONDUCTIVITY; INVERSION; DEEP; CONSTRAINTS; SYSTEM
WOS研究方向	Geochemistry & Geophysics
WOS记录号	WOS:001052832200001
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/283841
作者单位	China University of Geosciences - Beijing; University of Munster; China Geological Survey; Institute of Geology, Chinese Academy of Geological Sciences; Chinese Academy of Geological Sciences
推荐引用方式 GB/T 7714	Sheng, Yue,Jin, Sheng,Comeau, Matthew J.,et al. Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau[J],2023,619.
APA	Sheng, Yue.,Jin, Sheng.,Comeau, Matthew J..,Hou, Zengqian.,Becken, Michael.,...&Ye, Gaofeng.(2023).Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau.EARTH AND PLANETARY SCIENCE LETTERS,619.
MLA	Sheng, Yue,et al."Evidence for partial melting and alkali-rich fluids in the crust from a 3-D electrical resistivity model in the vicinity of the Coqen region, western Lhasa terrane, Tibetan Plateau".EARTH AND PLANETARY SCIENCE LETTERS 619(2023).