Prolonged Late Mesoproterozoic to Late Triassic Tectonic Evolution of the Major Paleo-Asian Ocean in the Beishan Orogen (NW China) in the Southern Altaids

The accretionary processes and the continental growth of Altaids are still controversial. Beishan orogen is situated in southernmost an ideal tectonic site to address these issues. In this study, we report results new field-based lithological mapping structural analysis on Huaniushan complex orogen, which composed blocks serpentinized ultramafic, gabbro, basalt, chert, limestone, other rocks within a strongly deformed cleaved matrix sandstone schist. Our zircon U-Pb date reveal that gabbro block formed at 504 ± 3 Ma. geochemical isotopic data gabbroic basaltic show they relics Mid-Ocean-Ridge (MORB)-type Ocean-Island-Basalt (OIB)-type oceanic lithosphere, with high values ε Nd (t) (+4.3–+14.5) Hf (+8.07–+17.74). maximum depositional ages (MDAs) two were dated 309 5 Ma 502 11 Ma, respectively. isotopes detrital zircons from sandstones indicate derived only Shuangyingshan–Huaniushan arc north. Accordingly, was part Liuyuan fringed arc, and, therefore, by northward subduction plate. Combined basalt yields age 1,071 concluded has Furthermore, sedimentary have 1,071–270 920–234 respectively, suggesting Ocean open ca. 234 Thus, studies Ocean, major branch Paleo-Asian may experienced prolonged history, starting late Mesoproterozoic (1,071 Ma) terminating later than Triassic (234 Ma), long development series seamounts and/or plateaus emplaced into complex.