The final collision of the CAOB: Constraint from the zircon U–Pb dating of the Linxi Formation, Inner Mongolia

Abstract

a b s t r a c tThe Linxi Formation occupies an extensive area in the eastern Inner Mongolia in the Central Asian Orogenic Belt (CAOB). The Linxi Formation is composed of slate, siltstone, sandstone and plant, lamellibranch microfossils in the associated strata. Major and trace element data (including REE) for sandstones from the formation indicate that these rocks have a greywacke protolith and have been deposited during a strong tectonic activity. LA-ICPMS UePb dating of detrital zircons yield ages of 1801 to 238 Ma for four samples from the Linxi Formation. 425e585 Ma, together with the w500 Ma age for the metamorphism event previously determined for Northeast China, indicates that their provenance is the metamorphic rocks of Pan-African age that have a tectonic affinity to NE China. A few older zircons with UePb ages at 1689e1801 Ma, 1307e1414 Ma, 593e978 Ma are also present, revealing the Neoproterozoic history of NE China. The youngest population shows a peak at ca. 252 Ma, suggesting that the main deposition of the Linxi Formation was at late Permain. Moreover, the ca. 250 Ma zircon grains of all four samples yield weighted mean 206 Pb/ 238 U ages of 250 AE 3 Ma, 248 AE 3 Ma, 249 AE 3 Ma, and 250 AE 2 Ma, respectively. These ages, together with the youngest zircon age in the sample ZJB-28 (ca. 238 Ma), suggest that the deposition of the Linxi Formation extended to the early Triassic. Combining with previous results, we suggest that the final collision of the Central Asian Orogenic Belt (CAOB) in the southern of Linxi Formation, which located in the SolonkereXra MoroneChangchun suture, and the timing for final collision should be at early Triassic.Ó 2015, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

The lithosphere structure of the Great Xing’an Range in the eastern Central Asian Orogenic Belt: Constrains from the joint geophysical profiling

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Superposed deformation in the Helanshan Structural Belt: Implications for Mesozoic intracontinental deformation of the North China Plate

“…The N-S shortening have been mainly attributed to closure of the Paleo-Asia Ocean at 250-200 Ma (Wang et al, 2011), or to collision between North China and the Yangtze Plate Zhang et al, 2014). However, recent research suggests that the final collision of the Central Asia Orogenic Belt (CAOB) occurred at the end of the Permian to the Early Triassic (Deng et al, 2009;Han et al, 2014), which is inconsistent with the timing of the WNW-ESE trending structures described above. The timing of NNE-SSW oriented shortening appears to have been closely related to collision of the North China Plate with Yangtze Plate along the Qinling-Dabie Orogen.…”

The latest geodynamics in Central Asia: primary and secondary mantle melting anomalies in the context of orogenesis, rifting, and lithospheric plate motions and interactions

“…Герцинские (силлурийско-каменноугольные) островные дуги Южного мегаблока (как части Южномонгольско-Хинганской или Тяньшань-Южнохингалинской зо-ны) отделялись от Северо-Китайского кратона и аккретированных к нему террейнов Солонкерским швом [Yanshin, 1974;Belichenko, Boos, 1990;Tseden et al, 1992;Kozakov et al, 2007;Windley et al, 2007;Parfenov et al, 2003;Wan, 2010]. Солонкерский па-леоокеан закрылся, по разным оценкам, в поздней перми или раннем триасе, во временном интервале от 275 до 248 млн лет назад [Ruzhentsev et al, 1989;Kovalenko et al, 1996;Şengör, Natal'in, 1996;Parfenov et al, 2003;Wan, 2010;Qin et al, 2013;Zhou, Wilde, 2013;Han et al, 2015].…”