SHRIMP Zircon Dating of Meta-Sedimentary Rock from the Qinling Group in the North of Xixia, North Qinling Orogenic Belt: Constraints on Complex Histories of Source Region and Timing of Deposition and Metamorphism
摘要
This paper carried out a geochronological research on zircons from a meta-sedimentary rock (biotite plagioclase gneiss) sample in the north of Xixia, a typical distribution area of the Qinling Group in the Qinling orogen belt. The zircons show complex core-rim structures in CL images. A total of forty-seven zircons have ages ranging from >3.0 Ga to ~400 Ma. Combined with early data, some conclusions can be drawn as follows: 1) the protolith of the meta-sedimentary rock of the Qinling Group was formed after Paleoproterozoic; 2) the zircon features show that the studied rock underwent metamorphism from upper amphibolite-granulite facies in early stage; and 3) the source region providing detritus for the Qinling sediments shows a long and complex evolution history, there might be Archean basement in Qinling and adjacent areas.