Geoelectric Architecture of Eastern Ladakh: New Insights from Magnetotelluric Imaging Across the Trans-Himalayan Suture System

The eastern Ladakh region, forming a key segment of the Trans-Himalaya, preserves the tectonic archive of the India–Eurasia collision that led to the closure of the Tethys Ocean, subduction of the Indian lithosphere, and subsequent growth of the Himalayan orogen. Despite its tectonic relevance and geothermal potential, the crustal geophysical framework of this region has remained poorly constrained. To fill this gap, we conducted detailed magnetotelluric (MT) investigations along two strategically positioned profiles: Ukdungle–Hanle–Koyul and the Tso Moriri–Pangong corridor, covering the major suture zones and associated lithotectonic units. Results from the Ukdungle–Hanle–Koyul profile delineate a steeply dipping Indus Suture Zone (ISZ), an 8–10 km thick Ladakh batholith, and a prominent ~6 km-wide conductive body at ~4 km depth beneath the Tso Moriri Crystalline (TMC) complex, with an upward extension along the ISZ. Three-dimensional modelling further reveals that these shallow conductors merge downward into a laterally extensive deep conductive zone interpreted as partial melt underlying southern Tibet and extending into eastern Ladakh. The second MT profile from the TMC complex toward the Pangong metamorphics highlights additional crustal transitions, including the shift from highly resistive Indian crust to moderately resistive crust across the ISZ, the deeper root of the Ladakh batholith at ~18–20 km, and a major 20–25 km deep conductor beneath the Shyok Suture Zone (SSZ), interpreted as a fossil magma chamber. A systematic geoelectric-strike rotation from NW–SE to E–W northward reflects the transition from Himalayan tectonics to the plateau-dominated regime of western Tibet. Together, the profiles also indicate an eastward thinning of the Ladakh batholith, refining the regional crustal architecture.
Keywords: Trans Himalaya, Tso Moriri Crystalline (TMC), Pangong metamorphics, Ladakh Batholith