Timing, Petrogenesis, and Setting of Paleozoic Synorogenic Intrusions from the Altai Mountains, Northwest China: Implications for the Tectonic Evolution of an Accretionary Orogen

Geochemistry, zircon U–Pb ages and Hf isotopes of the Paleozoic volcanic rocks in the northwestern Chinese Altai: Petrogenesis and tectonic implications

“…(e.g. Windley et al, 2002;Jahn et al, 2004;Wang et al, 2006Wang et al, , 2009Yuan et al, 2007;Tong et al, 2007;Briggs et al, 2007).…”

Confirmation of ultrahigh-temperature metapelitic granulite in the Altay orogen and its geological significance

“…The metamorphic zones can be divided into kyanite-type and andalusite-type, and show a main feature of greenschist-amphibolite facies metamorphism [13,15], and locally granulite facies metamorphism [16][17][18]. The greenschist-amphibolite facies metamorphism was thought to have occurred in the late Devonian (*365 Ma) [11,15], probably associated with the arc-continent collision during the early to middle Palaeozoic [11,19]. Other researchers further consider that the low-pressure high-temperature metamorphism occurred in the period of 380-390 Ma, and was associated with the development of ridge-subduction and slab-window formation [20][21][22].…”

“…A large number of granitoids and orthogneisses occupy about 40 % of rocks in the orogenic belt, consisting mainly of early Palaeozoic syn-orogenic and late Palaeozoic post-orogenic granitic bodies, and may be subdivided into tonalite, granodiorite and biotite granite, with minor two mica granite [19]. The ages of the former are mainly between 370-450 Ma, with a geochemical signature of arc magmatism [19,25], whereas the ages of the latter are between 270-280 Ma [26][27][28][29], with a mantlederived signature [30].…”

“…The ages of the former are mainly between 370-450 Ma, with a geochemical signature of arc magmatism [19,25], whereas the ages of the latter are between 270-280 Ma [26][27][28][29], with a mantlederived signature [30]. Additionally, some mantle-derived mafic intrusive rocks and an ultramafic intrusive complex of about 280 Ma occur at Kalatongke and Wuqiagou in Fuyun County [31,32].…”

“…This is not only consistent with the tectonic setting reflected from the anticlockwise P-T path, but also compatible with the development of several gneissic thermal dome structures in the Altay region. Since the major phase of amphibolite facies metamorphism in the Altay orogenic belt occurred in the Devonian [15], and its corresponding arccontinent collision formed the framework of this orogenic belt [11,19], together with the time consistence of the UHT metamorphic event with the large Erqis deep fault or shear zone [33], it is suggested that this UHT metamorphism in the orogen could be an overprinting structural thermal metamorphic event caused by the Permian Tarim mantle plume activity.…”