ISSN 0016-8521, Geotectonics, 2013, Vol. 47, No. 4, pp. 291–309. © Pleiades Publishing, Inc., 2013. Original Russian Text © Yu.S. Biske, D.L. Konopelko, R. Seltmann, 2013, published in Geotektonika, 2013, Vol. 47, No. 4, pp. 61–81. 291 INTRODUCTION The Tien Shan Orogen in its broad comprehension from the Qizilqum Hills 1 in the west to the Gobi Altay in the east is the Late Paleozoic (Hercynian in the broad sense of this term) collisional structure up to 3000 km in extent, which is accessible for investigation owing to the Cenozoic within-plate activation, which 1 The Tien Shan Mountains extend through China, Kazakhstan, Kyrgyzstan, and Uzbekistan. In each of these countries the cur- rently used geographic names differ in spelling and cannot be rationally unified. In this translation, the proper names are spelled according to the local styles and thus are changeable, e.g., Tian Shan, Junggar, Yili in China and Tien Shan, Zhongar, Ili elsewhere. Translator’s comment. has created a highly dissected mountain system. The central position in the Tien Shan region is occupied by the southern part of the Kazakhstan (Kyrgyz–Kazakh, Kazakhstan–Yili in other publications) paleoconti- nent, the crust of which was formed in the Silurian as a result of amalgamation of older, mainly Neoprotero- zoic continental masses and Early Paleozoic island arcs. The Precambrian blocks comprise the microcon- tinents of the Middle Tien Shan, and the Moyynqum and Ysyk-Köl massifs of the Northern Tien Shan (Fig. 1). The Central Tien Shan in publications by Chinese authors [44, 52, 78–80, 82] is a continuation of one of these massifs (the Ysyk-Köl Massif, in our opinion, though other interpretations are known). This narrow Geodynamics of Late Paleozoic Magmatism in the Tien Shan and Its Framework Yu. S. Biske a , D. L. Konopelko a , and R. Seltmann b a St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 199034 Russia b CERCAMS, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom e-mail: gbiske@hotmail.com Received May 10, 2012 Abstract—The Devonian–Permian history of magmatic activity in the Tien Shan and its framework has been considered using new isotopic datings. It has been shown that the intensity of magmatism and composition of igneous rocks are controlled by interaction of the local thermal upper mantle state (plumes) and dynamics of the lithosphere on a broader regional scale (plate motion). The Kazakhstan paleocontinent, which partly included the present-day Tien Shan and Qizilqum, was formed in the Late Ordovician–Early Silurian as a result of amalgamation of ancient continental masses and island arcs. The Devonian began here with heating of the mantle that resulted in the within-plate basaltic volcanism in the southern framework of the Kazakh- stan paleocontinent (Turkestan paleoocean) and development of suprasubduction magmatism over an exten- sive area at its margin. In the Middle–Late Devonian, the margins of the Turkestan paleoocean were passive; the area of within-plate oceanic magmatism shifted eastward, and the active margin was retained at the junc- tion with the Balqash–Junggar paleoocean. A new period of active magmatism was induced by an overall shortening of the region under conditions of plate convergence. The process started in the Early Carbonifer- ous at the Junggar–Balqash margin of the Kazakhstan paleocontinent and the southern (Paleotethian) mar- gin of the Qarakum–Tajik paleocontinent. In the Late Carboniferous, magmatism developed along the northern boundary of the Turkestan paleoocean, which was closing between them. The disappearance of deepwater oceanic basins by the end of the Carboniferous was accompanied by collisional granitic magma- tism, which inherited the subduction zones. Postcollision magmatism fell in the Early Permian with a peak at 280 Ma ago. In contrast to Late Carbonif- erous granitic rocks, the localization of Early Permian granitoids is more independent of collision sutures. The magmatism of this time comprises: (1) continuation of the suprasubduction process (I-granites, etc.) with transition to the bimodal type in the Tien Shan segment of the Kazakhstan paleocontinent that formed; (2) superposition of A-granites on the outer Hercynides and foredeep at the margin of the Tarim paleoconti- nent (Kakshaal–Halyktau) and emplacement of various granitoids (I, S, and A types, up to alkali syenite) in the linear Qizilqum–Alay Orogen; and (3) within-plate basalts and alkaline intrusions in the Tarim paleocon- tinent. Synchronism of the maximum manifestation and atypical combination of igneous rock associations with spreading of magmatism over the foreland can be readily explained by the effect of the Tarim plume on the lithosphere. Having reached maximum intensity by the Early Permian, this plume could have imparted a more distinct thermal expression to collision. The localization of granitoids in the upper crust was controlled by postcollision regional strike-slip faults and antiforms at the last stage of Paleozoic convergence. DOI: 10.1134/S001685211304002X 1 1 1