Abstract
The Himalayan foreland basin formed by flexure of the Indian Plate below the advancing orogen. Motion on major thrusts within the orogen has resulted in damaging historical seismicity, whereas south of the Main Frontal Thrust (MFT), the foreland basin is typically portrayed as undeformed. Using two-dimensional seismic reflection data from eastern Nepal, we present evidence of recent deformation propagating >37 km south of the MFT. A system of tear faults at a high angle to the orogen is spatially localized above the Munger-Saharsa basement ridge. A blind thrust fault is interpreted in the subsurface, above the sub-Cenozoic unconformity, bounded by two tear faults. Deformation zones beneath the Bhadrapur topographic high record an incipient tectonic wedge or triangle zone. The faults record the subsurface propagation of the Main Himalayan Thrust (MHT) into the foreland basin as an outer frontal thrust, and provide a modern snapshot of the development of tectonic wedges and lateral discontinuities preserved in higher thrust sheets of the Himalaya, and in ancient orogens elsewhere. We estimate a cumulative slip of ∼100 m, accumulated in <0.5 Ma, over a minimum slipped area of ∼780 km2. These observations demonstrate that Himalayan ruptures may pass under the present-day trace of the MFT as blind faults inaccessible to trenching, and that paleoseismic studies may underestimate Holocene convergence.
Funder
Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada
CIRES Visiting Fellow Program / NOAA
Cairn Energy
Publisher
Proceedings of the National Academy of Sciences
Reference52 articles.
1. A. Gansser , Geology of the Himalayas, (Interscience Publishers, 1964).
2. Cenozoic tectonic evolution of the Himalayan orogen as constrained by along-strike variation of structural geometry, exhumation history, and foreland sedimentation;Yin;Earth Sci. Rev.,2006
3. Gravity anomalies, flexure of the Indian Plate, and the structure, support and evolution of the Himalaya and Ganga Basin
4. D. W. Burbank , R. A. Beck , T. Mulder , “The Himalayan foreland basin” in The Tectonic Evolution of Asia, A. Yin , T. M. Harrison , Eds. (Cambridge University Press, Cambridge, UK, 1996), pp. 149–188.
Cited by
32 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献