The amalgamation of the Central Asian Orogenic Belt in the southwestern Tian Shan in Tajikistan is represented by tectono-magmatic-metamorphic processes that accompanied late Paleozoic ocean closure and collision between the Karakum-Tarim and Kazakh-Kyrgyz terranes. Integrated U-Pb geochronology, thermobarometry, pseudosection modeling, and Hf geochemistry constrain the timing and petro-tectonic nature of these processes. The Gissar batholith and the Garm massif represent an eastward, along-strike increase in paleodepth from upper-batholith (similar to 21-7km) to arc-root (similar to 36-19km) levels of the Andean-syn-collisional Gissar arc, which developed from similar to 323-288Ma in two stages: (i) Andean, I-type granitoid magmatism from similar to 323-306Ma due to northward subduction of the Gissar back-arc ocean basin under the Gissar microcontinent, which was immediately followed by (ii) syn-collisional, I-S-type granitoid magmatism in the Gissar batholith and the Garm massif from similar to 304-288Ma due to northward subduction/underthrusting of Karakum marginal-continental crust under the Gissar microcontinent. A rapid isotopic pull-up from similar to 288-286Ma signals the onset of juvenile, alkaline-syenitic, post-collisional magmatism by similar to 280Ma, which was driven by delamination of the Gissar arclogite root and consequent convective asthenospheric upwelling. Whereas M-HT/LP prograde metamorphism in the Garm massif (650-750 degrees C/6-7kbar) from similar to 310-288Ma was associated with subduction-magma inundation and crustal thickening, HT/LP heating and decompression to peak-metamorphic temperatures (similar to 800-820 degrees C/6-4kbar) at similar to 2886Ma was driven by the transmission of a post-collisional, mantle-derived heat wave through the Garm-massif crust.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626289 |
| Date | 10 1900 |
| Creators | Worthington, James R., Kapp, Paul, Minaev, Vladislav, Chapman, James B., Mazdab, Frank K., Ducea, Mihai N., Oimahmadov, Ilhomjon, Gadoev, Mustafo |
| Contributors | Univ Arizona, Dept Geosci, Department of Geosciences; University of Arizona; Tucson Arizona USA, Department of Geosciences; University of Arizona; Tucson Arizona USA, Institute of Geology, Earthquake Engineering and Seismology; Tajik Academy of Sciences; Dushanbe Tajikistan, Department of Geosciences; University of Arizona; Tucson Arizona USA, Department of Geosciences; University of Arizona; Tucson Arizona USA, Department of Geosciences; University of Arizona; Tucson Arizona USA, Institute of Geology, Earthquake Engineering and Seismology; Tajik Academy of Sciences; Dushanbe Tajikistan, Institute of Geology, Earthquake Engineering and Seismology; Tajik Academy of Sciences; Dushanbe Tajikistan |
| Publisher | AMER GEOPHYSICAL UNION |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | ©2017. American Geophysical Union. All Rights Reserved. |
| Relation | http://doi.wiley.com/10.1002/2016TC004285 |
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