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Evolution of the Pamir salient: new sedimentological and paleomagnetic constraints from the southeastern Tajik Basin

Abstract : The Pamir Plateau forms a prominent salient into central Asia. Previous kinetic models suggest that the salient was formed since the late Eocene, by radial thrusting and dextral transfer faulting along its western and eastern boundaries, respectively. In this study, a new sedimentary section in the southeastern Tajik Basin that spans the Early Cretaceous to late Miocene was examined using sedimentological and paleomagnetic methods. Vertical-axis tectonic rotation data indicate counterclockwise rotation of 54.6±5.4º for Late Cretaceous–early Paleogene rocks, 55.5±5.2º for late Eocene–early Miocene rocks, and 67.3±5.0º for middle–late Miocene rocks. These new data, agreeing with previous studies, indicate that large counterclockwise rotation of the Tajik Basin did not happen until the middle–late Miocene; and thus challenge kinetic models that require earlier initiation of the Tajik Basin rotation, e.g., late Eocene or Oligocene, in response to growth of the Pamir salient. Field observations and AMS (anisotropy of magmatic susceptibility) data show contrast deformation styles between the middle–late Miocene and older strata, most likely indicating deformation of the Early Cretaceous–early Miocene rocks during deposition of the middle–late Miocene strata. This deformation style is consistent with recent low-temperature thermochronology data, which infer intensified middle–late Miocene exhumation in the surrounding north Pamir and southwest Tianshan. Results of this study call for reconsideration of previous kinetic models for evolution of the Pamir salient.
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https://hal-insu.archives-ouvertes.fr/insu-02413412
Contributor : Isabelle Dubigeon <>
Submitted on : Monday, December 16, 2019 - 11:06:15 AM
Last modification on : Wednesday, January 15, 2020 - 1:26:29 AM

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  • HAL Id : insu-02413412, version 1

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Lin Li, Guillaume Dupont-Nivet, Pierrick Roperch, Mustafa Kaya, Niels Meijer, et al.. Evolution of the Pamir salient: new sedimentological and paleomagnetic constraints from the southeastern Tajik Basin. American Geophysical Union Fall Meeting 2019, American Geophysical Union, Dec 2019, San Francisco, United States. pp.T53A-04. ⟨insu-02413412⟩

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