Abstract Tural-Rajwadi group of hot springs (50−61.5 °C) is located in the southern part of the West Coast Geothermal Province (WCGP) of Maharashtra, India. The hot springs manifest in the basaltic terrain belonging to the Deccan Traps of Cretaceous-Paleocene age (∼65 Ma). To delineate the subsurface structures, a detailed geophysical exploration study has been carried out in the vicinity of the Tural-Rajwadi area for the first time deploying micro-gravity and micro-magnetic surveys in a grid of 1.25 × 4.0 km covering an area of 5 km2. The study shows prominent low gravity and low magnetic anomalies demarcating geothermal zones in the study area. Radial average power spectrum analyses of gravity and magnetic data infer seven interfaces of basalt lava flows in the subsurface. Evaluation of geophysical anomaly map reveals that the residual low gravity corroborates with a magnetic low anomaly zone and may indicate an association of a high-temperature gradient at shallow depth in the area. The study shows the presence of several NNW-SSE, NW-SE, NE-SW, and E-W lineaments, which predominantly control the manifestation of hot springs in the area. The distribution of faults, their boundaries, and depth extent have also been determined via derivative analyses, tilt derivative, and Euler’s deconvolution methods. Analyses of geophysical data using Werner deconvolution and radial average spectrum methods along two selected profiles indicate the presence of a vertical to sub-vertical conduits system extending to a deeper geothermal source in the study area. In addition, a 2D modeling study of gravity data along a 10 km profile estimates a shallow granite-gneiss basement in the depth range 770−800 m below ground level.

中文翻译：

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印度马哈拉施特拉邦西海岸地热省 Tural-Rajwadi 温泉群地球物理勘探及其意义

摘要 Tural-Rajwadi 温泉群（50-61.5 °C）位于印度马哈拉施特拉邦西海岸地热省（WCGP）南部。温泉出现在属于白垩纪-古新世（~65 Ma）德干圈闭的玄武岩地形中。为了描绘地下结构，在 Tural-Rajwadi 地区附近进行了详细的地球物理勘探研究，首次在 1.25 × 4.0 公里的网格中部署了微重力和微磁测量，覆盖面积为 5平方公里。研究表明，研究区存在显着的低重力和低磁异常，划定了地热区。重力和磁数据的径向平均功率谱分析推断出地下玄武岩熔岩流的七个界面。地球物理异常图的评估表明，剩余的低重力证实了低磁异常区，并可能表明该地区浅层高温梯度的关联。研究表明，存在几个 NNW-SSE、NW-SE、NE-SW 和 EW 纹路，它们主要控制该地区温泉的表现。断层的分布、边界和深度范围也已通过导数分析、倾斜导数和欧拉反褶积方法确定。沿两个选定剖面使用 Werner 反褶积和径向平均光谱方法对地球物理数据进行分析表明，存在延伸到研究区域更深地热源的垂直到亚垂直管道系统。此外，