Himanshu K. Sachan

Wadia Institute of Himalayan Geology

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Aditya Kharya

Wadia Institute of Himalayan Geology

Shashi Ranjan

National Institute of Hydrology

Divya Prakash

Shobhit University

Barun K. Mukherjee

Wadia Institute of Himalayan Geology

Chiara Groppo

University of Turin

Franco Rolfo

University of Turin

M. A. Quasim

Aligarh Muslim University

Asad Ahmad

Aalto University

K. Santosh

Wadia Institute of Himalayan Geology

Sameer K. Tiwari

Wadia Institute of Himalayan Geology

Cooperative Institutions

Wadia Institute of Himalayan Geology

Banaras Hindu University

Academy of Scientific and Innovative Research

National Geophysical Research Institute

Indian Institute of Technology Roorkee

Indian Institute of Science Education and Research Mohali

Council of Scientific and Industrial Research

Geological Survey of India

Aligarh Muslim University

Oil and Natural Gas Corporation (India)

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Tectono-metamorphic evolution of the Karakoram Terrane: Constrained from P–T–t–fluid history of garnet-bearing amphibolites from trans Himalaya, Ladakh, India

Journal of Asian Earth Sciences (2020)

Praveen Chandra Singh Himanshu K. Sachan Aditya Kharya Franco Rolfo Chiara Groppo

Protolith

10.1016/j.jseaes.2020.104293

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Citations (4)

Garnet response diamond pressure metamorphism from Tso-Morari region, Ladakh, India

Himalayan Journal of Sciences (2008)

Barun K. Mukherjee Himanshu K. Sachan

10.3126/hjs.v2i4.902

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Citations (11)

Tracing Late-Stage Fluid Sources and Vein Formation within Ophiolitic Mélanges from the Indus Suture Zone, Ladakh Himalaya

The Journal of Geology (2021)

Aditya Kharya Himanshu K. Sachan Christopher J. Spencer Koushik Sen Divya Prakash

Quartz-calcite veins in the Zildat ophiolitic mélange (ZOM) and Shergol ophiolitic mélange (SOM) of the Indus Suture Zone preserve a diversity of fluid activity in the late stages of ophiolitic mélange formation. This article presents fluid-inclusion and isotope geochemistry of these veins to understand their source and evolution in terms of pressure and temperature. The microstructures of quartz and calcite veins indicate deformation temperatures between 200° and 400°C. The δ13C and δ18O values of calcite veins from the ZOM and SOM are within the mixing hyperbolas of marine and primitive-mantle fields in the mixing model. The Sr and Pb isotopic values of calcite veins from the ZOM suggest a mid-ocean ridge basalt (MORB) fluid source of vein formation that was radiogenically enriched by metasomatism in a suprasubduction zone. For the SOM, fluids may have originated from the enriched-mantle (EM) and the depleted-MORB-mantle rocks. It is inferred that the carbonic fluids were derived from ultramafic lithologies and oceanic crust that formed the ophiolitic mélange rocks, which also host these veins. These source rocks have EM and MORB geochemical signatures that are also obtained in the quartz-calcite veins, as characterized by their C-O-Sr-Pb isotopic ratios. The magmatic saline fluid is inferred to have formed in the early stages of vein formation and to have been subsequently diluted, as exemplified by the presence of low-saline secondary aqueous inclusions. The microthermometry fluid pressure-temperature estimation of veins from the studied sections suggests that the maximum depth of emplacement of veining fluid was about 24.5 MPa (corresponding to ∼2.5 km) at 336°C. The vein-forming fluids (calcareous and siliceous) were introduced into the fractures that developed in the host as a result of deformation.

Metasomatism

10.1086/716964

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Rapid aqueous phase SO2 oxidation in winter fog in the Indo-Gangetic Plain

EGU General Assembly Conference Abstracts (2013)

Himanshu K. Sachan Chinmoy Sarkar Baerbel Sinha

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Geochronology and phase equilibria modelling of ultra‐high temperature sapphirine + quartz‐bearing granulite at Usilampatti, Madurai Block, Southern India

Geological Journal (2017)

Divya Prakash Roopali Yadav S. Tewari Hartwig E. Frimmel Nikola Koglin

Sapphirine‐bearing granulite from Usilampatti in the Madurai block of southern India preserves a variety of mineral textures and reactions that help in reconstructing a three‐stage metamorphic evolution. Corroded biotite, sillimanite and quartz inclusions within garnet represent relics from the prograde history. Peak metamorphic conditions were attained with the development of sapphirine + quartz in textural equilibrium (Stage 1). This was followed by nearly isothermal decompression, leading to the formation of sapphirine + cordierite at Stage 2. Subsequent retrograde hydration (Stage 3) is only locally evident. Using the Perple_X software and the model system NCKFMASH, the peak P‐T conditions were estimated from core compositions, and the retrograde evolution was deduced from rim or symplectite compositions of different minerals as computed by isopleths of X Mg garnet, X Ca garnet, X Mg orthopyroxene, X Mg sapphirine and X Mg biotite. The P‐T conditions for Stage 1 thus obtained, and supported by thermodynamic modelling using the winTWQ programme, is approximately 9 kbar and 940°C. Stage 2 conditions were constrained as 6.7 kbar and 900°C. Dating of zircon and monazite in the sapphirine‐bearing granulite and associated gneisses by the U‐Pb method using LA‐ICP‐MS indicates metamorphic overprint of zircon (lower intercept ages of discordant data arrays) at 546 ± 8 and 547 ± 11 Ma and metamorphic growth of monazite between 542 ± 3 and 551 ± 2 Ma. Upper intercept ages for zircon point to zircon growth at approximately 2514 ± 66 Ma. Although it remains unclear whether the metamorphic age data refer to Stage 1 or Stage 2 or, most likely, a continuum between both, they clearly document a late Ediacaran age for ultra‐high temperature (UHT) metamorphism in the area, which, based on the obtained P‐T path, was most likely the result of crustal thickening followed by uplift and erosion. Thus, it is concluded that the sapphirine‐bearing granulites formed in response to Pan‐African orogeny that led to the collision of the western and eastern Madurai domains, whereas initial zircon growth probably took place during late Neoarchaean arc magmatism that formed much of the western domain. Copyright © 2017 John Wiley & Sons, Ltd.

Cordierite

10.1002/gj.2882

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Citations (23)

Mineral Chemistry and Geothermobarometry of Amphibolite-Granulite Facies Basement Rocks Concealed Below Deccan Volcanic Covered 1993 Killari Earthquake Region, Maharashtra, India

Journal of the Geological Society of India (2021)

Priyanka Tripathi Himanshu K. Sachan V. Rajagopalan O.P. Pandey Sujeet Kumar Dwivedi

Geothermobarometry

Amphibole

Hornblende

10.1007/s12594-021-1871-3

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