Paleozoic multiple subduction-accretion processes of the southern Altaids

An Early Permian (ca. 280Ma) silicic igneous province in the Alxa Block, NW China: A magmatic flare-up triggered by a mantle-plume?

“…However, these diagrams could instead reflect the tectonic settings in which the protoliths were formed, or reflect the melting of mixed sources (e.g., Li et al, 2003). The tectonic setting of the~280 Ma granitoids can be constrained, however, by the timing of ocean closure between the CAOB and Alxa Block (i.e., Paleo-Asian Ocean), although this timing is itself highly disputed (e.g., Wang et al, 2010b;Wilhem et al, 2012;Xiao et al, 2009Xiao et al, , 2010. Numerous Early Permian (ca.…”

Metasomatized lithosphere–asthenosphere interaction during slab roll-back: Evidence from Late Carboniferous gabbros in the Luotuogou area, Central Tianshan

“…Recent studies of Early Permian mafic-ultramafic complexes from the Beishan area in the southernmost CAOB suggest they were emplaced in the subduction-related environment (Ao et al, 2010). They also indicate that particular examples of accretionary orogenesis in the southern part of the CAOB may represent episodes within a longer-lived process (Ao et al, 2010;Xiao et al, 2009). Consequently, multiple episodes of accretion likely occurred in the CAOB (Xiao et al, in press) and were likely to be still ongoing during the Late Carboniferous in the western Tianshan.…”

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

“…Early Paleozoic sedimentary rocks mostly occur in the Central domain, while late Paleozoic sedimentary and volcanic rocks are exposed in other domains (e.g. He et al, 1990;Windley et al, 2002;Chen and Jahn, 2002;Long et al, 2007Long et al, , 2010Sun et al, 2008;Xiao et al, 2009). The Early Paleozoic Habahe flysch sequence is considered as the oldest sedimentary sequence in the Chinese Altai.…”

“…Sengör et al, 1993;Windley et al, 2007;Cawood et al, 2009), during which various terrains (e.g. ophiolites, seamounts, island arcs and microcontinents) were accreted onto the southern margin of the Siberia Craton (Buslov et al, 2001;Badarch et al, 2002;Khain et al, 2003;Kuzmichev et al, 2005;Windley et al, 2007;Kelty et al, 2008;Xiao et al, 2008Xiao et al, , 2009). Long-lasting accretionary process results in mélanges, disorder of regional stratigraphy and development of thrust faults, while subduction of oceanic crust brings crustal materials into mantle and enhances intensive crust-mantle interactions (Sengör and Natal'in, 1996).…”