Zircon and muscovite ages, geochemistry, and Nd–Hf isotopes for the Aktyuz metamorphic terrane: Evidence for an Early Ordovician collisional belt in the northern Tianshan of Kyrgyzstan

Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

“…Chu-Ili was separated from the North Tien Shan Microcontinent throughout the Ordovician. Accretion of the two in the Early Ordovician (Late Floian: 480 to 475 Ma), depicted by Kröner et al (2012, fig. 19), is not supported because, firstly, there is no evidence for the existence of an active margin along the south-western side of Chu-Ili facing Zhalair-Naiman; secondly, instead of a hypothetical Lower to Middle Ordovician accretionary wedge attached to Chu-Ili, successions of oligomict slope-rise deposits of the Upper Cambrian to Middle Ordovician rocks can be traced almost continuously for 600 km along its south-western margin.…”

“…Thus it is likely that Kalmykkol-Kokchetav was a source of crustal fragments within the western of the Boshchekul Terrane. The Precambrian zircon age spectra of Kalmykkol-Kokchetav have no similarity with those of Tarim and North Tien Shan (Degtyarev et al 2015, p. 587), although Kröner et al (2012) stated that Late Precambrian zirconic spectra of North Tian Shan show similarity to 'Mid Tien Shan' (= Karatau Naryn) and Tarim.…”

Detrital zircons from Neoproterozoic sedimentary rocks in the Yili Block: Constraints on the affinity of microcontinents in the southern Central Asian Orogenic Belt

“…1). It was formed by long-lived Paleozoic subduction of the Paleo-Asian Ocean and accretions of several microcontinents (e.g., Yili Block, Chinese Central Tianshan Block, Ishim-Middle Tianshan in Kyrgyzstan, Aktau-Junggar in Kazakhstan, Gao et al, 2007Gao et al, , 2011Kröner et al, 2012Kröner et al, , 2013. In China, this orogenic belt is divided into four tectonic units, namely the Chinese North Tianshan (NT), the Yili Block (YB), the Chinese Central Tianshan Block (CTB) and the Chinese South Tianshan (ST) (Fig.…”

“…The CAOB is a complex collage of ancient microcontinents, island arcs, seamounts and oceanic plateaux (Sengör and Natal'in, 1996;Jahn et al, 2000Jahn et al, , 2004Xiao et al, 2004;Windley et al, 2007;Eizenhöfer et al, 2014;Han et al, 2015;Eizenhöfer et al, 2015a,b;Han et al, 2016a,b). Microcontinents and continental fragments are considered to have been incorporated into the CAOB during its accretion (Windley et al, 2007;Gao et al, 2011;Kröner et al, 2012;Alexeiev et al, 2015;Zhang et al, 2015aZhang et al, ,b,c, 2016. However, their origins are still controversial, with some researchers assuming that some microcontinents within the CAOB had a Gondwana derivation and were then accreted onto the southern margin of the Siberian Craton (Zonenshain et al, 1990;Buslov et al, 2001;Dobretsov et al, 2003;Kheraskova et al, 2003;Laurent-Charvet et al, 2003;Xiao et al, 2010).…”

Geochemistry, zircon U–Pb ages and Lu–Hf isotopes of early Paleozoic plutons in the northwestern Chinese Tianshan: Petrogenesis and geological implications

“…Similar granitoids in the SYGB and CTGB provided zircon U-Pb ages of 523-424 Ma and 479-416 Ma, respectively (Gao et al, 2009b;Han et al, 2004;Li, 2011a;Long et al, 2007b;Qian et al, 2009;Shi et al, 2007;XBGMR, 1993;Xu et al, 2010;Yang and Zhou, 2009;Yang et al, 2006;Zhu et al, 2006). In addition, several early Paleozoic magmatic belts have recently been documented in neighboring regions such as the Kyrgyz northern Tianshan (470-472 Ma) and the East Kyrgyz Range (449-451 Ma) (Kröner et al, 2012), the Kyrgstan Northern Tianshan (441-461 Ma) (Kröner et al, in press, 2013b), as well as the Chun-Yili Mountain (475-508 Ma) (Alexeiev et al, 2011). These Pearce, 1995Pearce, , 2008.…”