Petrologic Characteristics And Petrogenetic Study Of Intrusive Rocks In TangLi Mining Area,North Wuyishan Area

Lizikeng volcanic basin is located in the north wuyi orogenic belt,where found many Cu-Pb-Zn ore deposit with good prospecting.However,there are a lot of dispute over the petrogenesis and tectonic settings research in this area recent years.Tangli mining area is located in the northwestern of Lizikeng volcanic basin.The intrusive rock of Tangli are significant rock record of tectonic properties in the subduction and collision process.Therefore,this article select intrusive mass in Tangli mining area as our research object,combined with petrologic characteristics,geochemical and Sr-Nd-Pb isotope analysis,petrogenesis and tectonic settings of the rocks are discussed systematically in this paper.?1?After lithology and geochemical research,we recognise the intrusive rock of Tangli mining area two main lithology.They are biotite quartz monzonite and granite porphyry.The similar evolution characteristics of it's main elements suggest they were product of magmatism in the same period.This paper use of zircon LA-MC-ICPMS U-Pb dating two samples,the result shows that the diagenetic age is 138.02±0.49 Ma and 138.7±1.2 Ma,both for the early cretaceous,late mesozoic intrusion.?2?The biotite quartz monzonite SiO₂ content change in 63.25 65.44%,Al2O3 content is between 16.44 17.31%,total alkali content change in 9.22 9.65%,K2O/Na2 O ratio between 1.76 2.09,A/CNK between 1.04 1.19.The granite porphyry SiO₂ content change in 71.75 74.79%,Al2O3 content is between 12.56 13.70%,total alkali content change in 8.31 9.45%,K2O/Na2 O ratio with 1.76 2.09,A/CNK between 1.47 2.40.Both of them with rich K2 O and alkali,low-Fe Mg,peralumious,devided to calc-alkalic series of igneous rock.?3?The amount of REE in the Tangli mining area is high,the LREE and HREE fractionated obviously,the Eu is negative abnormality,and the REE distribution pattern is the right incline type of the LREE enriched.The LILE,such as Rb,Th,Pb are enriched.The HIFS such as Ba,Nb,Ta,P,Ti deficit.No obvious Ce negative abnormality.ISr 0.7091 on average,initial ?Nd?t?values from 10.49 to 7.59 and depleted-mantle model ages?T2DM?is bout 1.7 Ga,?206Pb/204Pb?i values is 18.010,?207Pb/204Pb?i values is 15.587,?208Pb/204Pb?i values is 38.479,belong to the rock type for the "I" to make the transition to "S" type granite.?4?The tectonic setting of Tangli mine are intrusive rock is continent and ocean converges in late mesozoic,low angle of the Pacific plate subduction,the formation of the NE,NNE nappe tectonic,causing the crust thickening,maga from crust and mantle mixing,the magma invasion process contamination by a certain degree.The early cretaceous intrusive rock in Tangli are was formed from the continent and ocean converges tectonic setting of yanshan period.It was a transition from subduction setting to continent collision setting.