Early Paleoproterozoic continental crust magmatism in the Xueye area, Western Shandong, China: Evidence from U-Pb age and trace element geochemistry of zircon

The basement of North China Craton (NCC) is a research hotspot in the field of Precambrian geology, as it contains a great deal of information about the formation and evolution of continental lithosphere. In this paper, LA-ICP-MS zircon U-Pb dating and trace element analysis has been carried out on a monzogranite sample from the basement of the Xueye area in Western Shandong, North China. Although no concordia age can be obtained from the 206Pb/238U and 207Pb/235U data of the zircon grains, these data are distributed along a discordant line, the upper intersection of which gives the formation age of the sample (2356Ma). The concentrations of some trace elements, such as U, Yb, Y, Hf, Th and P, in the zircon grains strongly indicate that the sample is a product of continental crust magmatism. Besides, the relative less extent of Eu anomalies as well as the high concentrations of Th and Pb of the zircon grains indicate that the sample does not belong to anorogenic granitoid. Therefore, the monzogranite is orogenic and its formation may be related to continent-continent or ocean-continent collision. As a result, it can be inferred that a rigid continental plate had been formed by early Paleoproterozoic. Zircon grains in this sample have experienced different extent of alteration since their formation. Most of the zircon grains that have been analyzed have experienced serious alteration, which indicates that there has been intense hydrothermal activity in this area since early Paleoproterozoic.