Aptian Magmatic Activity And Mineralization In Dongqiao-Shenzha Area Of Tibet

The comprehensive analysis of the magmatic activity in Dongqiao-Shenzha area was conducted in basis of the detailed field geological survey to research area,combined with 1/250000 scale regional geological surveys,1/50000 scale regional geological surveys/ mineral geological surveys,relevant scientific research reports,published papers,dissertations,and the geochronological and petrochemical data of the research area for nearly 20 years from mentor team members,and in basis of many tools,such as chronology,petrography,and rock geochemistry.The following basic understanding was obtained:1.The ages of medium-acidic intrusive rocks in the Bange area and Xiongmei-Shesuo area were respectively123±1Ma?114±08Ma and 113.49±0.87 Ma,which were formed in the Aptian.Magmatic rocks in the Aptian are mainly calc-alkaline-high-potassium,calcium-alkaline,and I-S granites.2.In the study area,Apt magmatic activity was the most active,revealing a large area of medium-acid magmatic rock.In the basis of combining previous achievements and the results of this research,the distribution of Apt magmatic rocks in Dongqiao-Zhenzao area in Tibet was systematically determined,that is,the intrusive rocks are mainly concentrated in the northeast-southwest line,while there is no distribution in the northwest and southeast areas,and the rock ages are concentrated between 124-113 Ma Ma.The Aptian volcanic rocks,which are relatively concentrated,are mainly distributed on the west side of the research area.They are mostly found in the Donis group and have a small range of age changes,ranging from 116-113 MMa.3.The data of the main volume,trace amount,and rare earth element of the rock mass of this study were plotted,it was concluded that the collected second-stage rock mass samples all fell in the corresponding granite and granodiorite range,which is consistent with the field name and belongs to sub-alkaline rock series and to the calcium alkaline-high potassium calcium alkaline series.Combined with previous data,all granite samples in the Aptian are relatively enriched in LILE,such as Rb,Th,U,and depletion of high field strength elements,such as Nb,P,Ta,Ti.A small amount of plagioclase crystals remain were occurred during the evolution of magma before crystallization.LREE in granodiorite are relatively enriched,and the differentiation of light and heavy rare earth elements is obvious.No plagioclase crystal remains in the evolutionary process before magmatic crystallization.4.Combining with this research and previous data,the same magmatic rocks were exposed in the north of the research area,and large-area arc magmatic rocks were exposed in the south.Through preliminary research,it was determined that the Aptian Dongqiao-Shanzha area is in the stage of the close collision between the Beibuban-Nuyang,and the subduction stage of the Gangdise in the south,and then a schematic diagram is drawn.5.Under the guidance of the basic idea of resource potential analysis,combined with typical mineral deposits,mineralization displays,and method anomaly information,five metallogenic prospects were preliminarily delineated,namely: Xiongmei-Shesuo Prospect,Zanzongcuo prospect,Dongqiao prospect,Maqian prospect,Yugulayuan prospect.