Study On The Genetic Mineralogy And Diagenesis Of Sanfoshan Pluton In The Early Cretaceous, Jiaodong

anfoshan pluton is the component of Muping-Rushan gold metallogenic zone,which locate at the Jiaodong easternuplift region in North China Craton eastern margin. It belongs to a part of the Weideshan super-unit, invading in Kunyushangranodiorite pluton.In the south itengages with the Duogushan biotitemonzogranite. It is a typical Mesozoic granite,and its‘representative rocks exposed in Rushan Sanfoshan area.According to the main elements discrimination diagram and combined with the petrographic study, it showsthat Sanfoshanbelonging to monzogranite-syenite granite series, the main part is monzogranite. With the analysis of petrology and geochemistry of major, trace and rare earth elements features, the author calculate magma water content xH2Ois3.53%~4.57%, differentiation index 85~95.It belongs to a kind of quasi-aluminium to weakly-peraluminous, K-rich calc alkaline highly fractionated I-type granite.Through the three geochemical analysis of Sanfoshan,the plutonbelongs aluminum-weakly peraluminous high differentiation I-type molten granite.Genetic mineralogy study with electron probe analysis and zircon trace element test shows that k-feldspar, plagioclase, hornblende, biotite average crystallizing pressure is 10*108Pa.Its source region at a depth of about 33 Km.The magma shows mixing characteristics but close to crust source.The author calcite the formation of the magma chamber pressure(P) with an average of 2.8*108Pa and emplacement depth of about 9Km.It says that Sanfoshan pluton is a medium~deep phase intrusive pluton.The 593 ℃ crystallization temperature is calculated by using two-feldspar temperature-gauge, and cimnined with the results of the previous zircon thermometer. The temperature((T) of crystallization of Safoshanplutonis 700 ~ 800 ℃.The Ce positive anomaly,Eu negative anomaly of zircon and hornblende analysis indicates that the magma with high oxygen fugacity.The biotite study shows that magma oxygen fugacity fo2 is ΔFMQ> ΔFMQ+2.According to the zircon U-Pb dating shows that the granite-forming age between the 120-112 Ma but three are three 135.6Ma, 136.1Ma, 133.8Ma data maybe the evidence of 130 Ma Kunyushan magma activities. According to Zhang(2011) analysed zircon Hf model-age results,there are two weighted average ages 2385 ±20Ma and 2096±65Ma.It indicates the source material may be Paleoproterozoic Jingshan or Fenzishan.Combined with the geological background, the emplacement mechanism can be summarized as follows: in Late Jurassic to Cretaceous affected by the Tethyan tectonic domain and the Pacific tectonic domain structure dynamic shift,and the middle and easternpart of the Chinese mainland regional institutional transformation occurs, North China Craton eastern margin came into the late Mesozoic extensional tectonic environment. In Early Cretaceous, along the orogen to split away from the fault system leads to upwelling asthenosphere ring material and mantle wedge partial melting, from upper mantle and lower crust magma intrusion.At about 120-112 Ma,syenogranite,fine-grained and coarse-grained monzonitic granite fomed, which constitute Sanfoshan pluton,for condensation differentiation and evolution in the process of crystallization.