Cenozoic deep crust in the Pamir

Jennifer Schmidt, Bradley R. Hacker, Lothar Ratschbacher, Konstanze Stübner, Michael Stearns, Andrew Kylander-Clark, John M. Cottle, A. Alexander, G. Webb, George Gehrels, Vladislav Minaev

Research output: Contribution to journalArticle

90 Scopus citations

Abstract

Multiple high-grade crystalline domes across the Pamir contain Barrovian facies-series metapelites with peak metamorphic assemblages of garnet + kyanite ± staurolite + biotite + oligoclase ± K-white mica. Thermobarometry yields pressures of 6.5-8.2 kbar and temperatures of 600-650 °C for the Kurgovat dome in the northwestern Pamir, 9.4 kbar and 588 °C for the west-central Yazgulom dome, 9.1-11.7 kbar and 700-800 °C for the east-central Muskol dome, and 6.5-14.6 kbar and 700-800 °C for the giant Shakhdara dome in the southwestern Pamir. These new data indicate exhumation of the Pamir crystalline domes from crustal depths of ~. 30-40. km. New titanite, monazite and zircon geochronology, in conjunction with published ages, illustrate that this metamorphism is Oligocene-Miocene in all but the Kurgovat dome (where it is Triassic). If the Pamir had a pre-collisional crustal thickness less than 30. km and if the India-Asia convergence within the Pamir is less than 600. km, the current 70. km-thick crust could have been created by plane strain with no net gain or loss of material. Alternatively, if the pre-collisional crustal thickness was greater than 30. km or India-Asia convergence within the Pamir is more than 600. km, significant loss of continental crust must have occurred by subhorizontal extrusion, erosion, or recycling into the mantle. Crustal recycling is the most likely, based on deep seismicity and Miocene deep crustal xenoliths.

Original languageEnglish (US)
Pages (from-to)411-421
Number of pages11
JournalEarth and Planetary Science Letters
Volume312
Issue number3-4
DOIs
StatePublished - Dec 15 2011

Keywords

  • Crustal recycling
  • Exhumation
  • Geochronology
  • Metamorphic petrology
  • Pamir

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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  • Cite this

    Schmidt, J., Hacker, B. R., Ratschbacher, L., Stübner, K., Stearns, M., Kylander-Clark, A., Cottle, J. M., Alexander, A., Webb, G., Gehrels, G., & Minaev, V. (2011). Cenozoic deep crust in the Pamir. Earth and Planetary Science Letters, 312(3-4), 411-421. https://doi.org/10.1016/j.epsl.2011.10.034