Petrography and zircon U–Pb isotopic study of the Bayanwulashan Complex: Constrains on the Paleoproterozoic evolution of the Alxa Block, westernmost North China Craton

Origin of the Alxa Block, western China: New evidence from zircon U–Pb geochronology and Hf isotopes of the Longshoushan Complex

“…All these data indicate that the Precambrian metamorphic basement of the western Alxa Block experienced the ca.1.85 Ga high-grade metamorphic event, and we interpret ca.1.85 Ga as the final formation time of the crystalline basement of the western Alxa Block. In the eastern Alxa Block, similar late ) metamorphic ages are also recorded in different basement rocks from the Bayanwulashan (e.g.,Dong et al, 2007, Wu et al, 2014 and the Diebusige Regions (e.g.,Geng et al, 2007Geng et al, , 2010 Dan et al, 2012a), further indicating the eastern and western Alxa Block may have experienced the same Late Paleoproterozoic tectonothermal events.…”

Tracking deep crust by zircon xenocrysts within igneous rocks from the northern Alxa, China: Constraints on the southern boundary of the Central Asian Orogenic Belt

“…7c). Geochronological studies have demonstrated multiple magmatic events in the YNH zone Zhou, 2010, 2012;Li et al, 2010;Shi et al, 2012;Wang, 2012;Gong, 2013;Feng et al, 2013;Zhang et al, 2013d;Dan et al, 2014a,b;Wu et al, 2014;Zheng et al, 2014), although magmatic rocks forming at several phases are not exposed or have been destroyed at the present erosion level (Fig. 7c).…”

“…Although knowledge on the Precambrian history is limited due to the restricted extent of exposed basement, the basement has been interpreted to be mainly composed of pre-Neoproterozoic medium-to high-grade metamorphic assemblages (ca. 2.4-1.7 Ga), such as the Diebusige metamorphic complex, the Bayanwula Shan metamorphic complex, and low-grade sedimentary sequences (Darby and Gehrels, 2006;Geng et al, 2006;Zhou and Geng, 2009;Dan et al, 2012;Wu et al, 2014), as well as several Neoproterozoic granites (929-904 Ma, Geng and Zhou, 2010;Dan et al, 2014b). The exposed igneous rocks include large granitic intrusions with minor diorite and mafic plutonic rocks (Fig.…”

“…Numerous zircon xenocrysts from several tectonic units were identified in many of these studies Zhou, 2010, 2012;Li et al, 2010;Wu, 2011;Shi et al, 2012;Wang, 2012;Gong, 2013;Feng et al, 2013;Zhang et al, 2013c;Dan et al, 2014b;Wu et al, 2014;Zheng et al, 2014). These zircon xenocrysts may provide a good opportunity to trace information on the deep continental crust and to constrain the boundary between the CAOB and the Alxa Block.…”

LateCarboniferous–earlyPermian arc magmatism in the south‐westernAlxaTectonicBelt (NW China):Constraints on the latePalaeozoic subduction history of thePalaeo‐AsianOcean

“…The Precambrian basement consists of granitic gneiss and metasedimentary rocks (Bureau of Geology and Mineral Resources of Nei Mongol Autonomous Region [BGMRNM], ). Their protoliths ages range from latest Archean–Palaeoproterozoic (~2.5–2.0 Ga; Dan, Li, Guo, Liu, & Wang, ; Wu et al, ) to early Neoproterozoic (Hu, Gong, Wu, Liu, & Liu, ). 40 Ar‐ 39 Ar dating on hornblende from the metamorphic basement rocks revealed early Permian cooling ages interpreted as affected by the amalgamation processes of the CAOB (Geng & Zhou, ).…”