Important crustal growth in the Phanerozoic: Isotopic evidence of granitoids from east-central Asia

The late Paleozoic to Mesozoic evolution of the eastern margin of the Central Asian Orogenic Belt in China

“…Referred to as the Altaids by Sengor et al (1993Sengor et al ( , 2014 and as the Central Asian Foldbelt in Russia (Sorokin et al, 2011), its evolution commenced in the Proterozoic and continued into the Cenozoic (Windley et al, 2007;Xiao et al, 2010). The recognition, based on Nd systematics and more recently confirmed by hafnium-in-zircon data, that most of the Phanerozoic rocks are juvenile (Jahn et al, 2000b(Jahn et al, ,2000cWu et al, 2000;Wang et al, 2015a,b) has led to questioning the commonly held tenet that crustal growth during the Phanerozoic was minimal. However, this premise has itself been questioned recently, with Kröner et al (2014) arguing that significant variations in zircon eHf values at any given magmatic age suggest that the granitoid magmas were derived from compositionally and chronologically heterogeneous crustal sources.…”

Geochemical and isotopic constraints on the evolution of Late Paleozoic dyke swarms in West Junggar, Xinjiang, China

“…In the present area, the undeformed mafic dykes dissect the deformational structures such as fold and faults which were related to subduction-accretionary process indicating the cessation of subduction-accretionary process when the mafic dykes were emplaced. Thus, the occurrence of mafic dykes in West Junggar indicate a within-plate extensional setting which is coeval with the widespread lithospheric extensional events in the North Xinjiang (Coleman, 1989;Han et al, 2006;Jahn et al, 2000aJahn et al, , 2000bWang et al, 2004;Ouyang et al, 2006;Pirajno et al, 2008) rather than a typical subductional environment (Geng et al, 2009(Geng et al, , 2011Liu et al, 2009a;Tang et al, 2010Tang et al, , 2012Yin et al, 2010;Zhang et al, 2011a). The arc signature exhibited in the trace element patterns can be well explained by partial melting of a SCLM which was recently metasomated by subduction process prior to Late Paleozoic.…”

“…The arc signature exhibited in the trace element patterns can be well explained by partial melting of a SCLM which was recently metasomated by subduction process prior to Late Paleozoic. The Late Paleozoic mafic dyke emplacements may be the pieces of vertical growth of continental crust in North Xinjiang (Nelson, 1992;Han et al, 1997;Jahn et al, 2000aJahn et al, , 2000bKovalenko et al, 2004;Chen and Arakawa, 2005). …”

Geochronology and petrogenesis of granitic rocks in Gangdese batholith, southern Tibet

“…Both Rb-Sr and Sm-Nd systematics are commonly applied to constrain the source characteristics of granites, as old crustal materials always show higher 87 Sr/ 86 Sr ratios, lower 143 Nd/ 144 Nd ratios and older Nd model ages than the juvenile crust [85] . This inverse Sr-Nd correlation makes it an effective method to trace the magma source and crustal evolution.…”