Abstract: Granitoids are well developed in the southern Yili Block intruding the Proterozoic metamorphic rocks of the Tekes Group. Their ages and tectonic settings are poorly constrained. Our field investigations indicate that the granitoids are composed of weakly foliated biotite granites, strongly foliated two mica granites and undeformed biotite granites. Whole-rock geochemical and zircon U-Pb geochronological analyses revealed that the weakly foliated biotite granites and strongly foliated two mica granites belong to peraluminous calc-alkaline series and formed during 438 Ma and 426 Ma, respectively. Whereas, the undeformed biotite
granites emplaced during 400-380 Ma and have geochemical features similar to typical calc-alkaline series, showing enrichment in the large ion lithophile elements and depletion of the high field strength elements. Combined with regional geological data and previous results, we propose that the Paleozoic granitoids in the study area resulted from two episodes of magmatism related to different tectonic settings, namely, the Early Paleozoic peraluminous calc-alkaline, weakly foliated biotite granites and strongly foliated two mica granites were generated in the post-orogenic setting during the amalgamation of the Kazakhstan microcontinent, and the mid-late Paleozoic calc-alkaline, undeformed biotite granites were produced in an active margin related to subduction of
the Junggar Ocean.

Key words: Kazakhstan Microcontinent, Yili Block, Western Tianshan Orogen, granitoids, Junngar Ocean, subduction orogeny