Provenance analysis and tectonic setting of the Upper Jurassic Series in Mohe Basin, northeast China: Implication for the closure of Mongol–Okhotsk Ocean

Abstract

The Mohe Basin, to the south of Mongol–Okhotsk suture belt (MOSB) closely, is a good window into investigations of the evolution of the Mongol–Okhotsk Ocean during the Late Mesozoic. Sandstone samples of the Upper Jurassic Series in the Mohe Basin, Mohe, and Kaikukang formations are studied in detail in terms of petrography, geochronology, and geochemistry. All samples have low compositional and textural maturity, which are located in the areas of dissected arc and basement uplift in Dickinson's discrimination diagrams. LA‐ICP‐MS U–Pb zircon dating yields the youngest concordant ages of 173 ± 4 Ma and 157 ± 3 Ma for the Mohe and Kaikukang formations, respectively, which constrain the maximum sedimentary periods of them. The peak ages of all concordant ages correspond identically to the regional magmatic activities on both the Siberian Craton and Erguna Block. All samples demonstrate geochemical characteristics not so different from the upper continental crust, whose provenance is felsic in lithology and is situated in active continental margins. Thus, a Mohe foreland basin and its binary provenance are strongly suggested, with the Erguna Block – a southern source and the Siberian Craton – a northern one. Based on all the evidence above, a simple tectonic model of the evolution of the Mongol–Okhotsk Ocean is raised, that is, from the Triassic to the Middle Jurassic; the Mongol–Okhotsk oceanic plate continued to subduct under the Siberian Craton and the Erguna Block, triggering intense magmatism in these areas. In the Late Jurassic, the rapid closure of the Mongol–Okhotsk Ocean caused the basement uplift and intense denudation which provided abundant sources of dissected arc and basement materials for the Mohe Basin.

Tectonic evolution of Mohe area, North‐east China: Evidence from the Early Ordovician to Early Cretaceous magmatism and tectonism

“…Mohe Basin, a foreland basin formed in the later Jurassic (Z. X. Guo et al, 2017; He, Li, Mo, & Sorokin, 2005; Liang et al, 2019; Q. Zhang et al, 2019), is located in the northern margin of the Erguna Block and the southern margin of Mongol–Okhotsk suture zone. The basement of the Mohe Basin is composed of Xinghuadukou Group and a small number of intrusive rocks (Figure 1c).…”

“…B. Wu & Zheng, 2004; W. L. Xu et al, 2013; Zhou & Wilde, 2013; Zhou et al, 2011, 2015, 2018; Zhao et al, 2016). There are still many disputes about the tectonic evolution of the Erguna Block from Early Ordovician to late Early Cretaceous (Fan, Guo, Wang, & Lin, 2003; Liang et al, 2019; Meng, 2003; J. Tang et al, 2015; Q. Zhang et al, 2019; Zhou et al, 2015; Zorin, 1999; Zorin, Zorina, Spiridonov, & Rutshtein, 2001). Some scholars believe that magmatic events in the Erguna Block during the Early Ordovician are mainly related to the collision and collage of Erguna Block and Xing'an Block (Ge, Wu, Zhou, & Rahman, 2005).…”

“…However, others believe that the magmatic event in this period was formed in the tectonic environment of the transition from compression to extension and was related to the closure of the Palaeo‐Asian Ocean between the Erguna Block and the Siberian Craton (G. Wu et al, 2015). For the Mesozoic magmatic events of the Erguna Block, it is generally believed that the Mongol–Okhotsk tectonic domain mainly influenced the Late Permian to Early Cretaceous (Dai et al, 2018; Fan et al, 2003; Liang et al, 2019; Meng, 2003; Q. Zhang et al, 2019; Zorin, 1999; Zorin et al, 2001). The Early Cretaceous may be influenced by the Palaeo‐Pacific Ocean and Mongol–Okhotsk Ocean dual tectonic domains (W. L. Xu et al, 2013).…”

“…The Mohe area is located north‐west (NW) of the Erguna Block and closed to the eastern part of the Mongol–Okhotsk suture zone. It is crucial to study the evolutionary history of the eastern part of the Mongol–Okhotsk Ocean and the western part of the Erguna Block (Liang et al, 2019; Q. Zhang et al, 2019).…”

“…Therefore, identifying rock genesis and the tectonic evolution of magmatic events in the Mohe area is essential in indicating the tectonic events in NE China. However, in recent years, numerous studies have focused on the formation of the sedimentary sequence in the Mohe area (Z. X. Guo et al, 2017; Liang et al, 2019; Wang et al, 2015; Q. Zhang et al, 2019). Nevertheless, it is scarce in the research on the genesis and tectonic background of magmatic events from Palaeozoic to Mesozoic in the Mohe area.…”