Tectonic implications of new zircon U-Pb ages for the Xinghuadukou Complex, Erguna Massif, northern Great Xing'an Range, NE China

The nature and the timing of formation of the Xinghuadukou Complex of NE China are important to further our understanding of the Precambrian geological evolution of the Erguna Massif and the eastern segment of the Central Asian Orogenic Belt (CAOB). Here, we present the results of zircon U-Pb dating of a metavolcanic rock and 11 granitoid basement samples collected from the complex. We use these data to determine the age and tectonic origin of the complex and to examine the linkages between this complex and the surrounding tectonic domains and older cratonic areas. Igneous zircons from the metavolcanic rock yield a magmatic age of ∼850 Ma, indicating that the supracrustal rocks that represent the original Xinghuadukou Group formed during the Neoproterozoic. Petrological data and new zircon U-Pb ages for these samples enabled the identification of multiple stages of granitoid magmatism within different sections of the Xinghuadukou “Group”, indicating that this group, which was originally thought to have formed contemporaneously actually records the emplacement of granitoids at 957-786, 479-418, 265, and 209-192 Ma. This result indicates that the Xinghuadukou Complex records multiple stages of magmatism and contains various Neoproterozoic supracrustal components. Combining the new age data with regional geological data, we propose that the Erguna Massif should be considered part of the Mongol domain as it has a close affinity to other blocks that formed part of this domain during the Neoproterozoic. These data suggest that all of the complexes and terranes within the Mongol domain belong to the CAOB and were finally accreted to the southern margin of the Siberian Craton in the early Paleozoic.