An Integral Sign Conductor in the Frontal Himalaya Region and Its Tectonic Interpretation

A 3-D thin sheet model is developed synthesizing the data from different small array studies in the frontal Himalaya region. Most of the regional anomaly is simulated by a single highly conducting zone approximating an integral sign in shape (∫). The integral sign conductor (ISC) is basically an extension of Trans-Himalayan Conductor at the northern and southern ends towards east and west respectively. The conductance map indicates that the crust beneath the Indo-Gangetic Plains (IGP) lying on the western side of the ISC is electrically one order more conducting than on the eastern part. The synthesis of many geophysical signatures has permitted to infer that the Indian shield contiguous to the frontal Himalaya is mosaic of two crustal blocks of contrasting geophysical properties. In such tectonic scenario, the ISC is seen as a northeast continuation of the Aravalli range beneath the IGP and is interpreted to represent accretion zone resulting from the collision or underthrusting of the eastern crustal block beneath the western block. The clustering of epicenters along the ISC marks the continued activation of this ancient structure.