Tectonic and crustal evolution in the NE Indian region from magnetotelluric studies
The north east Indian crust is a seat of complex tectonic processes, resulting from its simultaneous subduction along two orthogonal intercontinental thrusts, the Himalaya to the north and the Indo-Burman range to the east which meet each other at eastern syntaxial bend. Magnetotelluric studies over the Shillong plateau and lower Brahmaputra sediments have delineated the Dauki fault at deeper levels as a NE-SW striking thrust with a dip angle of about 30 degrees, along which the low resistivity layer of east Bengal sediments and the underlying oceanic crust subduct to the northwest. Another thrust,sub parallel to the Dauki thrust is observed in the lower Brahmaputra valley. This may be an intracratonic thrust within the Indian plate. The Shillong plateau and the overlying sediments seem to act as a supracrustal block, not directly participating in the subduction process. However in response to the compressive tectonic forces generated by the Himalayan and Indo-Burman subduction processes the hardened rocks of Shillong plateau, together with the Brahmaputra sediments drift eastwards relative to the softer east Bengal sediments along the surface expression of the Dauki fault leading to a dextral strike slip movement.In order to study the nature of these thrusts in the closer proximity of the eastern syntaxis, another profile(Tawang-Tejpur-Diphu) was surveyed passing through the Upper Brahmaputra valley and Mikir Hill region, about 200 km east of the earlier profile, separated by a NS trending Koppili fault. The strike and dip of the Dauki thrust show a reasonable continuation over this profile with an offset of about 20 km,which may be due to strike-slip movement along the Koppili lineament. This work is a part of our initiative in the NE India and some other transects as well as additional sites over the existing transects,are being covered. These will also be included in the presentation wherever possible.
Magnetotellurics tectonics Himalaya Indo-Burman range NE India
GOKARN S G GUPTA G SANABAM S S WALIA D
Indian Institute of Geomagnetism, Kalamboli Highway, Navi Mumbai-410218, India Center for Environmental Studies, North Eastern Hill University, Shillong-793022, India
国际会议
The 19th International Workshop on Electromagnetic Induction in the Earth(第十九届国际地球电磁感应学术研讨会)
北京
英文
115-120
2008-10-23（万方平台首次上网日期，不代表论文的发表时间）