Janybek Baslakunov (Kyrgyzstan)

Email: bjanybek @mail.ru

Thesis title:  HP and UHP metamorphic rocks of the Choloktor suite of the Atbashy Range (Southern Tien-Shan).

Supervisor:  Prof. Akira Takasu (2005-2007).

Eclogite-bearing complexes of the Atbashy Range of Kyrgyzstan occur in the Hercynian folded belt of the Southern Tien-Shan. The upper parts of the allochthon are composed of metamorphic rocks of the Atbashy complex. A narrow tectonic slab occurs in the northern margin of the Atbashy complex. This tectonic slab contains eclogite lenses, and is named as the Choloktor suite. Tectonically, the Choloktor suite is located in the uppermost part of the allocthon.

The geologic structures in the Choloktor suite has been observed along the Kembel Valley. The Choloktor suite consists of HP and UHP metamorphic rocks, including eclogites and glaucophane schists. These metamorphic rocks contain mineral evidence of HP and UHP metamorphism, including quartz pseudomorphs after coesite, and lawsonite and phengite with high Si concentrations (Dobretsov, 1974; Bakirov, 1989; Tagiri et al., 1996; Puelles and Takasu, 1996). Ophiolite complexes also occur in the Choloktor suite. These ophiolites can be considered as the protoliths of the eclogites.

The aims of my study are:

• To describe the HP and UHP rocks petrologically, and to determine the chemical compositions of the constituent minerals.
• To study the bulk rock chemistry of the HP and UHP rocks.
• To determine the metamorphic age of these rocks.
• To establish P-T conditions of the metamorphism.

I will carry out petrographic description of the thin sections by optical microscopy, and study metamorphic petrology, methods of age determination, and methods of chemical analysis. Mineral analyses with be made by EPMA, and whole-rock chemistry determined using XRF and ICP-MS.

Detailed study of the HP and UHP rocks and their surrounding lithologies will allow determination of the conditions of the metamorphic P-T-t paths of rocks, and improve our understanding of the geodynamic evolution of the area.