Near-surface high resolution imaging of a metallogenic zone in the northern fringe of Dalma volcanics in eastern India using electrical resistivity tomography

Lithologic boundaries from gravity and magnetic anomalies over Proterozoic Dalma volcanics

“…The three lithological units at depths ∼40, ∼25, and ∼15 m, respectively correspond to weathered intrusive/SGM, upper DVs and lower DVs and corroborate well with the major geological successions (table 1) obtained from drilling data at Parasi (22 • 57 N; 85 • 40 E) (figure 1) in the same geological domain as that of the study area; a proven gold prospective deposit (MECL 2010). The obtained results are in agreement with those of Adhikari et al (2016). They at a depth of ∼25 m obtained resistivity < 1 Ωm and attributed it to metallogeny coinciding to upper DVs.…”

“…Keating and Pinet (2011) have shown that, in general, the effect of bodies is less than the half of upward continuation height. ERT lines coincident with gravity and magnetic lines in the area show that the top of the ore body is ∼25 m and extends to a maximum depth of ∼50 m (Adhikari et al 2016). Following Keating and Pinet (2011) and keeping the ERT results in consideration, we have chosen the upward continuation at 150 m as regional anomaly both for gravity and magnetic studies.…”

“…North of DVs hosts gold deposits (Dunn 1929;Dunn and Dey 1942;Gupta 2010;Deb 2014; Geological Survey of India (http://data.gov.in/ catalog/location-gold-deposits-india-and-itssalient -features\#web\ catalog\ tabs\ block\ 1)). There has been limited geophysical work in this area (Maurya et al 2015;Adhikari et al 2016). Maurya et al (2015) carried out MT studies over Singhbhum Group Metapelites (SGM), Dalma volcanics (DVs) and Singhbhum Group Quartzite and Pelites (SGQP) and detected shallow conductors beneath it which coincides well with the proven gold deposit (MECL 2010).…”

“…The inductively coupled plasma atomic emission spectroscopy studies indicate the presence of Au, Ag, U and Cu as 0.75 ppm, traces, 22 ppm and 26 ppm, respectively (Maurya et al 2015). Adhikari et al (2016) carried out detailed electrical resistivity tomography (ERT) surveys over the detected conductor by MT studies (Maurya et al 2015) in the northern fringe of DVs. The survey was carried out to delineate the detected conductor.…”