Study Of The Geochemistry And Genesis Of Gold-black Rock Series In Alex Area

In this paper,the LA-ICP-MS zircon U-Pb dating and the geochemical characteristics of the rock are combined with 1: 1 million thematic geological mapping and other methods to study the age and tectonic environment and material source of the gold-bearing black rock strata in Alxa Right Banner TeBai.Through the lithogeochemistry characteristic to study on the tectonic environment and material source of black rock series.As the result,The ratio of MgO/CaO was low,Indicating sedimentary area in TeBai relatively humid climate;The ore bearing strata in the study area are relatively deficient in some high field strength elements such as U,Th,Nb and Ta;TeBai gold black rocks REE chondrite normalized curves are basically the same,Average value of REE is 159.23×10^-6,Average value of LREE is 139.68×10^-6,Average value of HREE is 19.55×10^-6,LREE enrichment,HREE loss of the negative correlation;Eu negative anomaly is more obvious,Ce has weak negative anomaly;According to the main and trace elements obtain The ore bearing clastic rock of TeBai mining area for the accumulation of the oceanic island arc and near the continental margin arc environment,The process of sedimentary evolution is relatively simple,The provenance mainly comes from the acid igneous rock zone in the recurrent orogenic belt,Participation of mafic rocks in the process of sedimentary diagenesis.According to the Mesoproterozoic Agulugou ownership dispute problem of strata in Alxa mesoprotozoic.Choose the ore bearing sericite quartz phyllite as the research object to carry out U-Pb geochronology of detrital zircon LA-ICP-MS in TeBai parts of the formation.Concordia age is mainly distributed in the 2 age interval,525⁴61Ma and 1505¹079 Ma,respectively.The peak age of the young group was 473±3 Ma.Limit the maximum sedimentary age of Middle Ordovician of Mesoproterozoic Agulugou in Alxa Right Banner TeBai.Reflect the frequency characteristics of age data,The formation has the characteristics of multi source and multi period supply,The 1505¹079Ma may be derived from the debris into the Middle Proterozoic granitic rocks in the Longshoushan group.The 525⁴61Ma debris originated from themagmatic arc produced by the subduction of the North Qilian ocean,The results indicate that the early Paleozoic magmatism in the Alxa block is related to the subduction of the North Qilian ocean,It is of great significance to understand the connection between the Alxa block and the North Qilian ocean.North Qilian oceanic crust with Qilian block subduction to the Alashan block in Cambrian-Ordovician period,Due to the impact of the collision,The northern Qilian oceanic crust gradually formed to form the northern Qilian orogenic belt,Qilian plots and Alashan plots are gradually Flattened.Magmatic rocks detritus of North Qilian orogenic belt continue to move northward to the TeBai to form a black rock-type strata.Tebai gold deposit?Zhulazaga gold deposit and Haoyaoerhudong gold deposit constitute the direction of nearly 230° black rock type gold belt Inner Mongolia central and western regions,This is of great significance for China to find black rock type gold mine.