气候变化领域集成服务门户(CCPortal): Elevated Equilibrium Geotherm in Stable Continental Shield: Evidence From Integrated Structural, Hydrological, and Electromagnetic Studies on Nonvolcanic Hot Springs in the Eastern Ghats Belt, India

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DOI	10.1029/2019JB017747
	Elevated Equilibrium Geotherm in Stable Continental Shield: Evidence From Integrated Structural, Hydrological, and Electromagnetic Studies on Nonvolcanic Hot Springs in the Eastern Ghats Belt, India
	Maitra A.; Singh A.; Keesari T.; Sharma S.P.; Gupta S.
发表日期	2020
ISSN	21699313
卷号	125 期号:2
英文摘要	Nonvolcanic hot springs occur within Neoproterozoic granulites of the tectonically stable Eastern Ghats Belt in the Indian shield. Penetrative granulite facies planar structural fabrics in the northern Eastern Ghats Belt are reoriented within an E-W striking, northerly dipping ductile shear zone that is subsequently dissected by WNW-ESE trending, subvertical pseudotachylite-bearing faults and fractures. Tube and dug wells in the area yield both thermal (~60 °C) and nonthermal (~28 °C) water. Chemical analyses reveal that the thermal water is richer in Na+, K+, and Cl−, with lower bicarbonate content. Stable isotope analyses (δ2H and δ18O) of the thermal and nonthermal waters both plot on the Global Meteoric Water Line; however, tritium and 14C ages indicate that the nonthermal water is relatively modern, while the thermal waters are older. This suggests that both waters come from distinct reservoirs. Very low frequency electromagnetic studies show that water circulates through the WNW-ESE trending fracture systems but also exists in isolated pockets within the crystalline country rock. Heat production studies reveal that some host rocks have exceptionally high heat-producing element concentrations, primarily as thorium within the minerals monazite and thorite. Meteoric waters entrapped for longer times near these heat-producing element-rich pockets undergo radiogenic heating, and are shielded from the nonthermal groundwater circulating within the fracture system. The high heat-producing element distribution in the crust resulting from Neoproterozoic geological events has, thus, elevated the present-day equilibrium geotherm in the Eastern Ghats Belt, forming sources for shallow-level, nonvolcanic hot springs within a tectonically inactive terrane. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Eastern Ghats Belt; elevated equilibrium geotherm; nonvolcanic hot springs; tritium dating; VLF electromagnetic; water geochemistry
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187986
作者单位	Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, India; Department of Earth Sciences, Indian Institute of Technology Bombay, Mumbai, India; Bhaba Atomic Research Centre, Mumbai, India
推荐引用方式 GB/T 7714	Maitra A.,Singh A.,Keesari T.,et al. Elevated Equilibrium Geotherm in Stable Continental Shield: Evidence From Integrated Structural, Hydrological, and Electromagnetic Studies on Nonvolcanic Hot Springs in the Eastern Ghats Belt, India[J],2020,125(2).
APA	Maitra A.,Singh A.,Keesari T.,Sharma S.P.,&Gupta S..(2020).Elevated Equilibrium Geotherm in Stable Continental Shield: Evidence From Integrated Structural, Hydrological, and Electromagnetic Studies on Nonvolcanic Hot Springs in the Eastern Ghats Belt, India.Journal of Geophysical Research: Solid Earth,125(2).
MLA	Maitra A.,et al."Elevated Equilibrium Geotherm in Stable Continental Shield: Evidence From Integrated Structural, Hydrological, and Electromagnetic Studies on Nonvolcanic Hot Springs in the Eastern Ghats Belt, India".Journal of Geophysical Research: Solid Earth 125.2(2020).