Seismotectonics of the Pamir

Bernd Schurr; Lothar Ratschbacher; Christian Sippl; Richard Gloaguen; Xiaohui Yuan; James Mechie

doi:10.1002/2014tc003576

journal article Aug 01, 2014

Seismotectonics of the Pamir

Bernd Schurr Lothar Ratschbacher Christian Sippl Richard Gloaguen

Xiaohui Yuan

James Mechie

Tectonics Vol. 33 No. 8 pp. 1501-1518 · American Geophysical Union (AGU)

View at Publisher Save 10.1002/2014tc003576

Abstract

AbstractBased on a 2 year seismic record from a local network, we characterize the deformation of the seismogenic crust of the Pamir in the northwestern part of the India‐Asia collision zone. We located more than 6000 upper crustal earthquakes in a regional 3‐D velocity model. For 132 of these events, we determined source mechanisms, mostly through full waveform moment tensor inversion of locally and regionally recorded seismograms. We also produced a new and comprehensive neotectonic map of the Pamir, which we relate to the seismic deformation. Along Pamir's northern margin, where GPS measurements show significant shortening, we find thrust and dextral strike‐slip faulting along west to northwest trending planes, indicating slip partitioning between northward thrusting and westward extrusion. An active, north‐northeast trending, sinistral transtensional fault system dissects the Pamir's interior, connecting the lakes Karakul and Sarez, and extends by distributed faulting into the Hindu Kush of Afghanistan. East of this lineament, the Pamir moves northward en bloc, showing little seismicity and internal deformation. The western Pamir exhibits a higher amount of seismic deformation; sinistral strike‐slip faulting on northeast trending or conjugate planes and normal faulting indicate east‐west extension and north‐south shortening. We explain this deformation pattern by the gravitational collapse of the western Pamir Plateau margin and the lateral extrusion of Pamir rocks into the Tajik‐Afghan depression, where it causes thin‐skinned shortening of basin sediments above an evaporitic décollement. Superposition of Pamir's bulk northward movement and collapse and westward extrusion of its western flank causes the gradual change of surface velocity orientations from north‐northwest to due west observed by GPS geodesy. The distributed shear deformation of the western Pamir and the activation of the Sarez‐Karakul fault system may ultimately be caused by the northeastward propagation of India's western transform margin into Asia, thereby linking deformation in the Pamir all the way to the Chaman fault in the south in Afghanistan.

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Cited By

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Building the Pamir-Tibetan Plateau-Crustal stacking, extensional collapse, and lateral extrusion in the Central Pamir: 2. Timing and rates

Daniel Rutte, Lothar Ratschbacher · 2017

Tectonics

Metrics

144

Citations

86

References

Details

Published: Aug 01, 2014
Vol/Issue: 33(8)
Pages: 1501-1518
License: View

Authors

B

Bernd Schurr

Deutsches GeoForschungsZentrum GFZ Potsdam Germany

L

Lothar Ratschbacher

Institut für Geologie Technische Universität Bergakademie Freiberg Freiberg Germany

C

Christian Sippl

Deutsches GeoForschungsZentrum GFZ Potsdam Germany; Now at Research School of Earth Sciences Australian National University Canberra ACT Australia

R

Richard Gloaguen

Institut für Geologie Technische Universität Bergakademie Freiberg Freiberg Germany; Now at Helmholtz‐Institut Freiberg für Ressourcentechnologie Freiberg Germany

X

Xiaohui Yuan

Deutsches GeoForschungsZentrum GFZ Potsdam Germany

J

James Mechie

Deutsches GeoForschungsZentrum GFZ Potsdam Germany

Cite This Article

Bernd Schurr, Lothar Ratschbacher, Christian Sippl, et al. (2014). Seismotectonics of the Pamir. Tectonics, 33(8), 1501-1518. https://doi.org/10.1002/2014tc003576

Seismotectonics of the Pamir

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