Late Permian intermediate and felsic intrusions in the eastern Central Asian Orogenic Belt: Final-stage magmatic record of Paleo-Asian Oceanic subduction?

Abstract

The Central Asian Orogenic Belt (CAOB), which formed by closure of the Paleo-Asian Ocean, is one of the largest Phanerozoic accretionary orogens on Earth. However, the timing of final closure of the Paleo-Asian Ocean remains debated. Here we present new zircon U-Pb dating, oxygen fugacity estimates, and whole-rock geochemical and Sr-Nd isotopic data from intermediate and felsic intrusive rocks in the Chunhua area of NE China to constrain their petrogenesis and assess the tectonic implications for the evolution of the eastern CAOB. Zircon U-Pb dating indicates that the intrusive rocks formed in the late Permian (257-261 Ma). Based on their chemical compositions, two groups of rocks can be identified. Group Ι consists mainly of dioritic rocks (e.g., gabbroic diorites, diorites and tonalites) with relatively low SiO 2 but high MgO contents and Mg# values. Petrological and geochemical characteristicsshow that Group Ι rocks were formed by mixing of mantle-and crust-derived magmas.Mafic microgranular enclaves within Group Ι rocks have high MgO contents (up to 9 wt%) and depleted isotopic compositions (ε Nd (t) = +4.3 to +7.2), and probably represent mafic end-member magmas derived from a metasomatized lithospheric mantle, which subsequently were injected into the felsic crustal magmas. In contrast, Group ΙI rocks are mostly granodiorites characterized by high SiO 2 and low Mg# values, with high Sr/Y and La/Yb ratios. These rocks were probably generated by partial melting of mafic lower crust with little or no addition of mantle materials.Trace element modeling suggests that intracrustal differentiation was dominated by hornblende fractionation and caused the high Sr/Y and La/Yb signatures of Group ΙI

Age and Tectonic Setting of Mesothermal Magmatic Hydrothermal Vein‐Type Pb–Zn–(Ag) Mineralization in the Xiaohongshilazi Deposit, Central Jilin Province, Northeast China

“…The central Jilin Province is located at the junction between the eastern segment of the CAOB and the North China Block and experienced the evolution of the Paleo‐Asian Ocean, Xing'an–Mongolian Orogeny, and the superposition of the Mesozoic subduction of the Paleo‐Pacific Plate (Zeng et al ., , ; Xu et al ., ). The Late Triassic–Early Jurassic geodynamic scenarios of this area remain debated, especially on the exact timing of final closure of the Paleo‐Asian Ocean and the initial subduction of the Paleo‐Pacific Plate beneath the Eurasian Plate (Wu et al ., ; Pei et al ., ; Zhou et al ., ; Xu et al ., ; Eizenhöfer et al ., ; Pei et al ., ; Ma et al ., ). In recent decades, numerous geochronological and petrogeochemical data of igneous rocks and sedimentary rocks have been accumulated in the region.…”

“…The central Jilin Province is located at the junction between the eastern segment of the CAOB and the North China Block and experienced the evolution of the Paleo-Asian Ocean, Xing'an-Mongolian Orogeny, and the superposition of the Mesozoic subduction of the Paleo-Pacific Plate (Zeng et al, 2012(Zeng et al, , 2013Xu et al, 2013). The Late Triassic-Early Jurassic geodynamic scenarios of this area remain debated, especially on the exact timing of final closure of the Paleo-Asian Ocean and the initial subduction of the Paleo-Pacific Plate beneath the Eurasian Plate (Wu et al, 2007;Pei et al, 2008a;Zhou et al, 2009;Xu et al, 2013;Eizenhöfer et al, 2014;Pei et al, 2018;Ma et al, 2019 Cao et al, 2013;Xu et al, 2013;Wang et al, 2017). This significant conclusion is also confirmed by the sedimentology, structural deformation, paleobiogeography, and paleomagnetism in the region (Zhou & Wilde, 2013 (Pei et al, 2008a, b;Xu et al, 2013).…”

Singularity Analysis of Volcanic Ages and Implications for Tectonic Setting in the Mesozoic, Great Xing’an Range, Northeast China

“…Firstly, Mesozoic volcanic rocks are widely distributed not only in the main continental area of China but also in Korea and Japan [2], which cannot be explained by the subduction of the Mongol-Okhotsk Ocean. Secondly, the ophiolitic mélange along the Solon-Ker suture zone at the southern margin of the GXR and the Late Permian intermediate and felsic intrusions indicates that the final closure of the Mongol-Okhotsk Ocean occurred during the Middle or end-Permian (252-272 Ma) [27,28]. It is very difficult to interpret why large-scale volcanic rocks are in the early Cretaceous, rather than in the Permian.…”

Heat- and melt-fluxed melting of lower continental crust: Insights from two types of subduction-related granitoids in northeastern China and the implications for crustal reworking and growth

“…1B), including the Erguna, Xing'an, and Songliao blocks and the Jiamusi-Khanka massifs (Zhou and Wilde, 2013). From the Neoproterozoic to late Paleozoic, archipelago-type accretionary orogenesis dominated the area of NE China (Xiao et al, 2003;Ma et al, 2019). The amalgamation of multiple terranes (e.g., arc systems and microcontinents) led to various NE China blocks being combined (Zhou and Wilde, 2013).…”