Juxtaposition of adakite, boninite, high-TiO2 and low-TiO2 basalts in the Devonian southern Altay, Xinjiang, NW China

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

“…During this period, a subduction-related setting was suggested by geochemical studies of mafic to intermediate volcanic rocks, granitoids and clastic rocks in the Chinese Altai (Niu et al, 1999(Niu et al, , 2006Xu et al, 2003;Zhang et al, 2004;Chen et al, 2006;Long et al, 2008aLong et al, , 2010. Nd isotopic characteristics of the granitoids indicated a significant addition of juvenile materials, suggesting that mantle-derived magmatism played an important role in the formation of early Paleozoic granitoids in the Chinese Altai (Jahn et al, 2000;Yuan et al, 2007;Wang et al, 2009).…”

Magmatic sequences in the Halasu Cu Belt, NW China: Trigger for the Paleozoic porphyry Cu mineralization in the Chinese Altay–East Junggar

“…Furthermore, according to previous researches in the southern margin of Chinese Altay Mountains (Niu et al, 1999(Niu et al, , 2006, the occurrence of juxtaposed Devonian boninite, high-TiO 2 and low-TiO 2 basalts, adakites, which were produced by partial melting of subducted young oceanic crust, together with the cherts, turbidites, and minor gabbros also indicate an island arc setting (Liu et al, 1993;Xu et al, 2003;Niu et al, 2006;Xiao et al, 2009b). Moreover, the tectonic setting of the arcs and intervening seaways in the Paleozoic is further supported by the dismembered ophiolites distributed in the East Junggar region (Xiao et al, 2009b), for example, the Armantai and Kelameili ophiolites, which mark the residues of PAO branches.…”

Magnesian andesites in north Xinjiang, China

“…1). Both lateral accretion of arc complexes and vertical accretion of underplated mantlederived materials are evident from island arc volcanic rocks, Neoproterozoic to late Paleozoic ophiolites and Paleozoic alkali-rich granites with positive eNd values (Zhao et al 1993(Zhao et al , 1996(Zhao et al , 2006aJahn et al 2000Jahn et al , 2004Han et al 1997Han et al , 2006Gao et al 2006;Niu et al 2006a). The tectonic framework and evolution of north Xinjiang remains the subject of debate, including the issue of whether it is composed of Phanerozoic accretionary orogenic belts or terranes (Xiao et al 2006), or Neoproterozoic basements inlaid in Phanerozoic orogenic belts ).…”

“…1b). In addition, the origins of strong mineralization of Cu, Ni, Au and Pb, Zn have been proposed to be related or partially related to these high-magnesian igneous rocks in north Xinjiang (Chen et al 1996;Niu et al 2006a;Wang et al 2006). Most of them are large-or giant-scale deposits, such as the large scale Ashele Cu and Zn ore deposit, Axi Au ore deposit and Tuwu-Yandong Cu ore deposits.…”

“…Magnesian andesites, dacites and diorites are widespread in north Xinjiang. They have been referred to mainly as HMAs or boninites in the literature (Zhang et al 2003;Niu et al 2006a;Wang et al 2006). High-Mg andesites contain clinoenstatite and are characterized chemically by having 52-63% SiO 2 ,[8% MgO and \0.5% TiO 2 (Kikuchi 1889;Le Maitre 2002).…”