What happens along the flank and corner of a continental indenter? Insights from the easternmost Himalayan orogen and constraints on the models of the India-Asia collision
Abstract
Investigations of continental collisions often focus on thrust belts oriented perpendicular to the plate-convergence direction and exclude belts that bound the flanks of a continental indenter despite being crucial to understanding the collisional process. Research of the Himalayan orogen, for example, has mostly centered on the east-trending thrust belt between the eastern and western syntaxes, resulting in inadequate examination of the north-trending Indo-Burma Ranges located along the eastern margin of India. To better understand the development of the entire Himalayan orogenic system, we conducted field mapping across the Northern Indo-Burma Range (NIBR), situated at the intersection of the eastern Himalaya and Indo-Burma Ranges. Our research shows that major lithologic units and thrust faults of the Himalaya extend to the NIBR, suggesting a shared geologic evolution. The structural framework of the NIBR consists of a southwest-directed thrust belt cored by a hinterland-dipping duplex, like the Himalaya. However, the Northern Indo-Burma orogen is distinct based on (1) the absence of the Tethyan Himalayan Sequence and southern Gangdese batholith, (2) the absence of the South Tibetan detachment, (3) crustal shortening greater than 80%, (4) an incredibly narrow orogen width of 7-33 km, (5) exposure of an ophiolitic mélange complex as a klippe, (6) and right-slip shear along the active range-bounding thrust fault. Furthermore, lithospheric deformation along the flank and northeast corner of India is characterized by right-slip transpression partitioned between the thrust belt and right-slip faults. Such a regime is interpreted to accommodate both contraction and clockwise rotation of Tibetan lithosphere around India, consistent with existing continuum deformation and rotation models.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.T43E..05H
- Keywords:
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- 8104 Continental margins: convergent;
- TECTONOPHYSICS;
- 8110 Continental tectonics: general;
- TECTONOPHYSICS;
- 8159 Rheology: crust and lithosphere;
- TECTONOPHYSICS;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS