Die metamorphe Entwicklung und Geochronologie von Blauschiefern und den unmittelbar assoziierten Nebengesteinen im südlichen Tianshan in Tadschikistan

• Antragsteller: Professor Dr. Reiner Klemd
• Fachliche Zuordnung: Mineralogie, Petrologie und Geochemie ; Paläontologie
• Förderung: Förderung von 2013 bis 2015
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 239213992

High-pressure/ultra high-pressure (HP/UHP) metamorphic rocks provide a unique opportunity to obtain insight the geodynamic evolution of collision orogens. Several HP/UHP metamorphic belts have been described in the Tianshan mountain range. The (U)HP belts in the South Tianshan of Kirgizstan and Tajikistan are believed to be the western continuation of the Tianshan HP/LT metamorphic belt in the Chinese South Tianshan. The HP/LT belts in the South Tianshan are mainly composed of blueschist-, eclogite-, and greenschist-facies meta-sedimentary rocks and some mafic meta-volcanic rocks with NMORB, EMORB, OIB and arc basalt affinities. Recent age data from the high-pressure rocks suggest a Carboniferous age for the peak of metamorphism. The prograde blueschists in the Fan Karategin belt in the South Tianshan of Tajikistan seem to stem from much shallower subduction zone depths than those in the Chinese South Tianshan and are reported to have transitional boundaries with the intimately associated greenschists. However, due to severe logistical problems the Tajik blueschists, which consist of sodic amphibole (glaucophane), albite, chlorite, phengite, epidote ± garnet ± quartz, were not recently sampled and investigated by modern petrological methods nor is the age of HP metamorphism constrained by radiogenic isotope studies. On the basis of the petrological and geochronological data from the Fan Karategin blueschist and from previously reported HP rocks from the other high-pressure belt of the South Tianshan, we anticipate to come up with a conclusive model that provides evidence for the development of the subduction-exhumation cycle which occurred during Late Carboniferous (?) times to gain insight the tectonometamorphic evolution of the South Tianshan and, thus, on the Paleozoic reconstruction of the western segment of the Central Asian Orogenic Belts (CAOB), one of the biggest collision complexes in the world.

• DFG-Verfahren: Sachbeihilfen
• Beteiligte Institution: Technische Universität Bergakademie Freiberg; Institut für Geologie