Geophysical techniques have been integral part of uranium exploration programme of the organization, particularly in delineating subsurface structures and geology, having bearing on ore localization. Some of the areas where these techniques have been effectively applied in establishing continuity of mineralisation are parts of Singhbhum shear zone, Jharkhand; Rohil-Ghateshwar area, Sikar district, Rajasthan; Umra area, Udaipur district, Rajasthan; Arbail area, North Kanara district, Karnataka; and in Bhima basin, Gulbarga district,Karnataka.
a) Field equipment
The various ground geophysical equipments presently available in AMD for field use are listed below.
i) Gravity meter (Sodin make)
ii) Total field proton magnetometer (ELSEC, EG&G and SCINTREX make)
iii) Cesium magnetometer (Scintrex make)
iv) Gradiometer (Scintrex make)
v) Resistivity/ Induced Polarization (IP) equipment (IPR-10, IGS-4 both Scintrex make & IPV-2 Phoneix make)
vi) Digital Self-Potential (SP) meter (Indigenously made)
vii) Electromagnetic (TURAM) equipment (Scintrex make)
viii) Transient Electromagnetic (TEM) equipment (EM-37 System, Geonics make) for ground survey
ix) Very Low-frequency (VLF, Scintrex make)
x) Slingram and horizontal loop EM (Scintrex make)
xi) Global Positioning System (GPS, 12 channel ML-150 Micrologic)
xii) Theodolite (Nikon and Wild make)
xiii) Transreceivers (Realistic, Panasonic & Motorola make)
b) Laboratory equipment
Instruments to measure physical properties of rocks in the laboratory are listed below.
i) Magnetic Susceptibility meter (Helmholtz coil set-up for laboratory & portable Terra Science make for in-situ measurements)
ii) Conductivity meter (PELICON PRODUCTS TORRANCE, USA)
iii) Density meter (Walker & Steel balance, Indian make) and precision electronic balance.
The group is equipped with the latest state-of-the-art software packages for processing of various geophysical data sets. Some of them are developed in-house and others purchased from abroad.
a) Software developed in-house
i) MAGPROS: Developed using FORTRAN for gravity and magnetic data processing.
ii) GMINV: An inversion software for gravity and magnetic data (2D) to obtain source parameters.
iii) EXPFIT: A DOS based software written in FORTRAN for interpretation of secondary IP effects.
b) Software purchased from abroad
i) GEOSOFT : This software package, in both DOS and WINDOW versions, was purchased from Geosoft, Canada for gravity and magnetic data processing. Also, forward Modelling of the profile data is included in GMSYS.
ii) OASIS MONTAJ: This is the Windows version of the “GEOSOFT” software package currently being used for aeromagnetic data processing.
iii) RESIX IP 2DI V4: This software package, purchased from Interprex Pvt. Ltd., USA, is available for processing of 2D resistivity and IP data.
iv) EM VISION: This software package, purchased from ENCOM Technology, Australia is available for analyses and Modelling of TEM data.
a) Ground Geophysical Surveys
So far, uranium exploration has relied predominantly on radiometric techniques as a direct detection process. However, as uranium resources near the surface have more or less been discovered, emphasis is presently shifted to explore deeper resources with non-radiometric geophysical techniques as potential tool. During the last four decades, the geophysics group of AMD has been actively involved in applying the non-radiometric geophysical techniques in geologically favourable terrains in different parts of the country for exploration of uranium.Nearly 2600 sq.km. area have been covered so far by various types of geophysical surveys in the country in different terrain conditions.
Areas where geophysical survey has been successfully utilized are (a) Singhbhum shear zone, Jharkand (b) Rohil - Ghateshwar area, Sikar district, Rajasthan, (c) Umra area in Udaipur district, Rajasthan, (d) Gogi area in Bhima basin, Gulbarga district, Karnataka, (e) Arbail area in North Kanara district, Karnataka.
b) Airborne Geophysics
Airborne magnetic data are acquired every time AGRS surveys is undertaken on any defined area. These airborne data are being processed and interpreted using state-of-the-art softwares and the product generated are generally high quality colour images that make visualization and interpretation more realistic.Data pertaining to nearly 5 lakhs sq. km of area has been processed so far.