Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex

A deep Schlumberger electrical sounding on the Namaqualand Granite‐Gneiss Complex has been carried out. The sounding center is situated near the middle of this body which measures approximately 500 km by 150 km. Whereas in previous investigations of a similar nature, current electrode spacings have generally been limited to less than 100 km, the use of a telephone line as an emission line has made it possible to extend the maximum current electrode separation to 270 km. Factors which may have influenced the reliability of the measurements include leakage tests, measuring accuracy, lateral effects, and surface electrode effects. The interpretation of the sounding curve which shows the existence of six layers was carried out with the aid of a computer. Some comments are made about the range of the principle of equivalence in the interpretation from the computed results. In particular the results suggest that the lower crust has an extremely high resistivity of approximately 40,000 ohm‐m supposedly due to dehydration. The final layer is conductive.

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Integration of geophysical, hydrogeological and geospatial analysis for groundwater assessment in Chotanagpur Granite-Gneiss Complex, Ranchi

10.22541/au.162435669.99582553/v1 ◽

2021 ◽

Author(s):

Gaurav Kumar ◽

Dewashish Kumar ◽

Pratibha Warwade

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Groundwater Resources ◽

Regional Scale ◽

Granite Gneiss ◽

Resistivity Tomography ◽

Weighted Overlay ◽

Gneiss Complex ◽

Aquifer Systems ◽

Groundwater Assessment

Integrated study combining electrical resistivity tomography, geology, hydrogeomorphology, and weighted overlay analysis of various surface and subsurface thematic layers proved to be a very useful tool for evaluating the heterogeneous hard aquifer systems for groundwater assessment and development. A comprehensive study was carried out at representative and varied geological settings viz., Chotanagpur Granite-Gneiss Complex (CGGC), Ranchi has been accomplished from geology and geophysical datasets. The electrical resistivity tomography results revealed potential target zones at three sites in the study area up to a maximum of 170 m depth with a large variation in aquifer resistivity ranging from 80 to 800 Ω.m. These significant findings depicted a good correlation and are validated with the lithology in the surrounding of the resistivity tomography results. Nevertheless, the weighted overlay technique act as an essential tool for spatial analysis and interpretation of potential groundwater zones in the study area as well as validated the geophysical depth models whereas in-depth study on geology and hydrogeomorphology provides a detailed hydrogeological scenario throughout the study area for the long-term sustainability of the groundwater resources both at a local and in regional scale in the typical hard rock aquifer system.

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Metamorphic evolution of the pelitic and mafic granulites from Daltonganj, Chhotanagpur Granite Gneiss Complex, India: Constraints from zircon U–Pb age and phase equilibria modelling

Geological Journal ◽

10.1002/gj.4340 ◽

2021 ◽

Author(s):

Ravi Ranjan Kumar ◽

Kenta Kawaguchi ◽

Shyam Bihari Dwivedi ◽

Kaushik Das

Keyword(s):

Phase Equilibria ◽

Granite Gneiss ◽

Metamorphic Evolution ◽

Gneiss Complex

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