Geochemistry, Geochronology, Hf Isotope and Tectonic Significance of Late Jurassic Huangdi Pluton in Xiuyan, Liaodong Peninsula

Late Jurassic magmatic activity in the Liaodong Peninsula was less and the research degree was lower. In this paper, zircon U-Pb dating, geochemistry and zircon Lu-Hf isotope analysis were carried out to further understand the tectonic dynamics of the Liaodong Peninsula in the Late Jurassic. The U-Pb weighted mean age of magmatic zircons in the Huangdi granite is 161.1±3.6 Ma (MSWD=1.4), indicating that the formation of the Huangdi granite is the Late Jurassic, which is the product of the Yanshanian magmatism. The pluton contains muscovite and other aluminum-rich minerals geochemical data show that the pluton is the peraluminum calcium alkaline series, enriched with LILE such as K, Rb, Cs, and Ba, and depleted HFSE such as Nb, Ti, and P. With the characteristics of light rare earth element enrichment and heavy rare earth element loss, Eu is a moderate negative anomaly (δEu=0.33-0.80).The average A/CNK value of the granite is 1.10, and the corundum molecule (>1%) appears in the CIPW standard mineral. It is considered that the pluton is an S-type granite that has undergone a high degree of crystallization differentiation. The CaO/Na₂O ratio of the Huangdi granite is less than 0.3, and the ε_Hf(t) is less than 0 (-36.968 to -23.298), indicating that the rock is formed by the mudstone of the earth's crust. The single-stage Hf mode age is T_DM=1 728-2 311 Ma, the two-stage Hf mode age is T_DM^C = 2 680-3 568 Ma. It is shown that the time when the constituent materials of the source rock of the pluton were separated from the mantle reservoir was Neo-Archean to Ancient Archean.In summary, the pluton is formed in the background of the ancient Pacific plate subduction to the Eurasian continent and the subduction angle becomes larger and submerged deeper.