Electrically Conductive Crust in Southern Tibet from INDEPTH Magnetotelluric Surveying

Abstract

The crust north of the Himalaya is generally electrically conductive below depths of 10 to 20 km. This conductive zone approaches the surface beneath the Kangmar dome (dipping north) and extends beneath the Zangbo suture. A profile crossing the northern Yadong-Gulu rift shows that the high conductivity region extends outside the rift, and its top within the rift coincides with a bright spot horizon imaged on the INDEPTH CMP (common midpoint) profiles. The high conductivity of the middle crust is atypical of stable continental regions and suggests that there is a regionally interconnected fluid phase in the crust of the region.

Electrical structure of the Himalaya of central Nepal: High conductivity around the mid‐crustal ramp along the MHT

“…We report here the first application of this technique (MT method) across the Himalaya of Central Nepal. This study extends the MT experiment carried out in southern Tibet that has revealed a zone of high electrical conductivity in the middle crust probably associated with partial melting [Chen et al, 1996;Pham et al, 1986]. In this paper, we first describe the structural setting, the data set, and the processing.…”

Thermal conditions during deformation of partially molten crust from TitaniQ geothermometry: rheological implications for the anatectic domain of the Araçuaí belt, eastern Brazil

“…Geophysical profiles and geological observations in hot orogens suggest that large volumes of the middle to lower crust were partially molten during deformation (e.g., Chen et al, 1996;McNamara et al, 1996;Nelson et al, 1996;Alsdorf et al, 1998;Unsworth et al, 2005). Indeed, the presence of even a small fraction of melt may dramatically reduce the strength of rocks and affect their tectonic behavior (e.g., Rosenberg and Handy, 2005;Labrousse et al, 2011).…”

Proceedings of the 25th Himalaya-Karakoram-Tibet Workshop

“…The MT interpretations of the data from the 1995 Yarlung-Zangbo suture profile on those 100 and 200 lines (Chen and others, 1996) were the definitive results that led to the influential interpretation of partial melt north of the suture. Field campaigns during Phase III resulted in MT acquisition from southern Tibet across the top of the Plateau to the Qaidam Basin north of the Kunlun Fault .…”

“…Regional resistivity structure of the Tibetan Plateau (Chen and others, 1996), using both broadband MT (BBMT) and long period MT (LMT) instrumentation. The MT interpretations of the data from the 1995 Yarlung-Zangbo suture profile on those 100 and 200 lines (Chen and others, 1996) were the definitive results that led to the influential interpretation of partial melt north of the suture.…”