Ph.D. student LONG Lingli and his teacher GAO Jun research the geochemical and geochronological studies of granitoid rocks from the Western Tianshan Orogen.

This study suggests a two stage model of continental growth of ‘syn-subduction lateral accretion of arc complexes’ and ‘post-collisional vertical accretion of underplated mantle material’, which may also be relevant for the western segment of the Central Asian Orogenic Belt (CAOB) in the Phanerozoic. The reworking and involvement of old crust are more obvious in the Western Tianshan Orogen compared to other parts of the CAOB comprising the Western Junggar, Eastern Junggar, Alataw and Altay terranes.

Fig. 1. Statistics of the zircon U–Pb ages obtained for the granitoids intruding into the Western Tianshan Orogen.

Fig. 2. Plot of initial Sr isotopic compositions (87Sr/86Sr) versus εNd(t) values showing that the granitoids in the Western Tianshan Orogen n have more enriched isotope compositions compared to the granitoids in the West Junggar, East Junggar, Alataw, and the Chinese Altay terranes.

Fig. 3. Tectonic model showing the evolution and the continental growth mechanism of the Western Tianshan Orogen.

Long. et al. Geochemical and geochronological studies of granitoid rocks from the Western Tianshan Orogen: Implications for continental growth in the southwestern Central Asian Orogenic Belt. Lithos. 2011, 126: 321-340（Download Here）