Taptapani hot spring region, EGMB, Odisha

The Eastern Ghats Mobile Belt (EGMB), a 900 km long collisional orogeny formed over the Meso- to Neo Proterozoic time period, spans along the east coast of the Indian subcontinent. Varying in width from 300 km in the north to about 50 km in the south, with three Archean cratons bordering on its three side- Dharwar (west), Bastar (north), Singhbhum (east), and the Bay of Bengal on its southern side. The proposed study area is located in the central portion of EGMB and also includes a part of the EGMB-north, within latitudes 19⁰ N -20.5⁰ N and longitudes 83.15⁰ E -86⁰ E, within the state of Odisha. The location of the Taptapani hot spring is 19.3° N 84.24° E, situated in the Ganjam District, Odisha. The predominant rock assemblages found within the proposed study area, i.e. Eastern Ghats Province, are charnockite gneisses, diatexitic gneisses, megacrystic granitoids, anorthosite complexes (Chilika Lake, Turkel, Jugsaipatna, and part of Bolangir complexes), alkaline rocks, calc-silicate gneisses, and khondalite gneisses. 

The shear zones falling under the study area are listed below with their respective trends:

Koraput-Sonepur shear zone (NE-SW), Mahanadi shear zone (WNW-ESE), Chilka lake shear zone (NE-SW), Digapahandi Shear zone (strike parallel to the belt- almost E-W), Aska Taptapani Shear zone (strike parallel to the belt- almost E-W), Banjanagar Shear zone (strike parallel to the belt- almost E-W), Baligurha- Tel Shear zone (strike parallel to the belt- almost E-W), Vamsadhara shear zone (N-S) and Nagavali shear zone (N-S). The hot spring to be studied is located in an area enclosed by the Chilka lake shear zone, Digapahandi Shear zone, Aska Taptapani Shear zone, and Baligurha-Tel shear zones, which could possibly be acting either as the conduits for the thermal water to the spring, or the cause of its genesis due to shear zone related tectonic activity. 

Free- air gravity data provided by an improved high-resolution gravity grid from the website of the Scripps Institution of Oceanography, https://topex.ucsd.edu/cgi-bin/get_data.cgi is utilized to study the regional trends in the gravity anomaly of the area. This global gravity model has approx. 2 mgal accuracy and is based on Geosat and ERS-1 satellites data along with new altimeter data from Jason-1 and CryoSat-2 satellites (Sandwell et al., 2014), (Kende et al., 2017). Bouguer anomaly map is obtained after applying topographic corrections using the topography data from the same website, to understand the gravity variations observed in the area. The Upward Continuation filter on the Geosoft software is used to perform regional-residual separation on the Bouguer anomaly for generating the regional (deeper sources) and residual (shallow sources) anomaly maps of the area around the hot spring. 

The Bouguer gravity anomaly from the global gravity grid data is inverted following the algorithm developed by Gomez-Oritz & Agarwal (2005)  and the modified version by Gao & Sun (2019), based on Parker-Oldenburg iterative inverse method, to obtain the Moho topography (Fig. 2) below the study area. An inverted Moho topography map is generated giving insights on the crustal variation below the study area.

Further techniques and interpretation is being carried out utilizing the dataset.

To be updated.