Azamat Bakirov (Kyrgyzstan)

Email: bakirov_a @mail.ru

Thesis title:  Geological and petrological study on the HP and UHP metamorphic rocks of the eclogite-bearing complex in the Makbal area, the Kyrgyz Tien-Shan.

Supervisor:  Prof. Akira Takasu (2004-2006).

The Tien-Shan is divided into three mountain ranges, the northern Tien-Shan, the middle Tien-Shan and the southern Tien-Shan. The Makbal eclogite-bearing complex occurs in the Caledonian folded belt of the Northern Tien-Shan and is located in the western part of the Kyrgyz Ridge. Eclogitic rocks are contained in the Akdzhon Group, the oldest formation in this region. The Akdzhon Group is divided into two units, the Neldy and Makbal Formations. The Makbal Formation is characterized by quartzose schists, but thin marbles also occur intercalated with quartz schists and pelitic schists. Eclogites and amphibolized eclogites crop out in the Akdzhon Group as lens- or sheet-shaped bodies ranging from one to several tens of meters in thickness. Coesite and inclusions of quartz pseudomorphs after coesite in garnet have been found in garnet-chloritoid-talc schists from the Makbal Formation. The protolith age of the Akdzhon Group is not known, but has been considered to be Lower Proterozoic. The Akdzhon Group is directly overlain by low-grade slates and marbles, the ages of which are thought to be upper Proterozoic. Ordovician granitic rocks have also caused contact metamorphosism of the Akdzhon Group.

The aims of the my present research are:

• o determine the physical conditions of the formation of the HP and UHP rocks;
• To determine metamorphic ages of the metamorphic rocks;
• To determine the protoliths and P-T-t paths of the metamorphic rocks;
• To discuss the tectonics of formation of the UHP metamorphic rocks and uplift of such deep-seated metamorphic rocks.

I will carry out petrographic description of thin-sections by microscope, chemical analyses of minerals by EPMA, and major and trace element analyzes of by XRF and ICP-MS. I will also determine the ages of the metamorphic rocks using Sm-Nd and U-Pb chronological techniques.

Detailed study of rocks from the HP and UHP complex in the Makbal Formation will reveal P-T-t conditions of the metamorphic rocks, and I intend to discuss the tectonic process of formation and exhumation of the UHP metamorphic rocks. This two-year study has important petrological and geological significance.