Age and geochemistry of western Hoh-Xil–Songpan-Ganzi granitoids, northern Tibet: Implications for the Mesozoic closure of the Paleo-Tethys ocean

Age and geochemistry of western Hoh-Xil–Songpan-Ganzi granitoids, northern Tibet: Implications for the Mesozoic closure of the Paleo-Tethys ocean: Comment

“…Therefore, we disagree the rollback model of Zhang et al (2014a) but acknowledge the high quality of the chronological, geochemical, and isotopic data presented by Zhang et al (2014a).…”

“…2 Late Triassic-Early Jurassic adakitic and I-type granitoids, and was interbedded by minor volcanic rocks (e.g., Weislogel, 2008;Zhang et al, 2007aZhang et al, , 2014a. This areally extensive terrain, juxtaposed with major Chinese continental blocks across several outstanding Paleo-Tethyan sutures, is a characteristic feature in central-western China, and forms a key to understanding the tectonic evolution of the Tethys and Asia (e.g., Zhang, 2001Zhang, , 2002Zhang et al, 2008bZhang et al, , 2012.…”

“…For example, deep seismic investigations (e.g., Wang et al, 2007), geochemical and isotopic studies on the magmatic rocks (e.g., Zhang et al, 2007aZhang et al, , 2014a, and tectonic modeling (Zhang, 2001(Zhang, , 2002 indicate that the complex may currently be underlain by a South China-type continental basement, although it has been traditionally interpreted to be floored by oceanic crust (e.g., Şengör et al, 1988;Nie et al, 1994;Zhou and Graham, 1996). A comprehensive investigation of the turbidites, incorporating geology, petrology, mineralogy, geochemistry and isotopes, reveals that the trubidites had complex sources including the Dabie ultrahigh-pressure metamorphic rocks, the Kunlun arc and the central…”

“…Recently, Zhang et al (2014a) proposed that rollback of the subducting Paleo-Tethys oceanic slab led to partial melting of overlying continental arc fragments and genesis of the We consider that there are two essential prerequisites for the correctness and applicability of the rollback model of Zhang et al (2014a): 1) the so-called Yidun arc,…”

“…Prior to the arc magmatism, the Yidun terrane could even be a passive margin that was separated from the Songpan-Ganzi Terrane by the pre-existing Ganzi-Litang Ocean., based on broad geologic, geographic and detrital zircon Zr-Hf isotope investigations (e.g.,Zhang et al, 2002; Wang et al, 2013). Therefore, it is clear that the Yidun arc (a Triassic arc; e.g.,Zhang et al, 2002; geologically correlated with the Kunlun arc (an arc active from the Cambrian through the Triassic; e.g.,Feng et al, 2010;Zhao et al, 2010; Dai et al, 2013; Li et al, 2013; ) and that the Yidun arc is not a part rifted from the Kunlun arc during the Triassic as proposed byZhang et al (2104a).Likewise, the the so-called Songpan-Ganzi and Hoh-Xil arcs ofZhang et al (2014a), cannot be geologically correlated with the Kunlun arc because no magmatic rocks older than the Triassic have been documented there there so far, and thus are not rifted parts from the Kunlun arc. Instead, the Songpan-Ganzi and Hoh-Xil areas are…”