Neoproterozoic–Early Cambrian igneous and sedimentary sequences in the Songliao Block, NE China: Records of Rodinia supercontinent evolution in eastern Central Asian orogenic Belt

Abstract

As the core of NE China blocks (i.e., Songliao, Jiamusi-Khanka, Erguna, Xing’an), the Songliao Block plays an important role in understanding the Precambrian evolutionary history of the eastern Central Asian Orogenic Belt (CAOB), as well as the linkage with reconstructions of Rodinia supercontinent. In this work, we present sedimentological, whole-rock geochemical, and zircon U–Pb–Hf isotopic data for the Neoproterozoic-early Cambrian igneous and sedimentary rocks in eastern Songliao Block. The newly identified 954 ± 2 Ma gneissic syenogranite pluton，916 ± 5 Ma meta-basaltic andesite, and the reported 929–841 Ma intrusive rocks formed the Precambrian crystalline basement of the eastern Songliao Block, which was overlain by the late early Neoproterozoic to early Cambrian stable sedimentary cover. The early Neoproterozoic (954 Ma) gneissic syenogranite was likely the product of muscovite dehydration melting of sedimentary rocks in deep crust during the post-collisional setting, probably associated with the collision between the Songliao and Jiamusi-Khanka blocks. The late Neoproterozoic to early Cambrian Chenming Formation displays characteristics of passive margin deposition, which formed after the opening of Paleo-Mudanjiang Ocean at 777 Ma. Integration of the spatial and temporal distributions of Neoproterozoic magmatism and sedimentation in the Songliao, Erguna, Xing'an and Jiamusi-Khanka blocks, as well as the geochemical variations from 0.96 to 0.73 Ga, we suggest that the blocks in NE China have experienced a similar two-stage Neoproterozoic tectonic evolutionary history associated with the Rodinia assembly and breakup. An early advancing subduction along peripheral Rodinia led to the collision and collapse extension between the Songliao and Jiamusi-Khanka blocks before 954 Ma, and the generation of 929–880 Ma syenites and granitoids in compressional continental arc setting. Then the retreating subduction formed the 850–737 Ma mafic and felsic rocks in Songliao, Erguna and Jiamusi-Khanka blocks, and caused breakup of the joint continent and opening of the Paleo-Mudanjiang and Paleo-Xinlin oceans, two branches of Paleo-Asian Ocean, since 777 Ma. In response to the oceanic spreading, the passive continental margin sedimentation developed in these blocks during 750–520 Ma.