Mesozoic Granite Structure Measurement And Typical Gold Deposits Geological Features In Jiaodong Area

The Jiaodong area is the third largest gold concentration area in the world,and its gold reserves and production have long accounted for about one-fourth of the country’s total.Predecessors have conducted systematic studies on deposits,structures,geochemistry and metallogenic regularities in this area.The formation of the Jiaodong gold deposit is closely related to the Mesozoic granites,but the study of the granite diagenetic structure is lagging behind.Under the guidance of the mentor,taking the Jiaodong granite diagenesis as the thesis topic,focusing on the observation and analysis of the same magmatic rock structure,has important scientific significance and the value of prospecting guides.I participated in the completion of the National Science and Technology Support Plan Project《Integration and Demonstration of Prospecting Geochemistry Methods in the Gold Mine of the Jiaozhou Northwest 》 and the Shandong Gold Group’s scientific research project《Three-Dimensional Research and Deep Prediction of the Erosion Mineralization System in the East of the Linglong Gold Field》,at the same time,through field structure measurement,indoor test analysis and comprehensive research,we have made progress in the diagenetic study of granites and contributed to the geological prospecting work in the mining area.Based on these efforts,the paper was submitted on time and some new achievements and understandings have been achieved:(1)The Guojialing squeezed granodiorite-like granodiorite was the main type,and it was involved in the completion of the structural geological filling of the exquisite Linglong similar quasi-bismuth biotite granite and the Luanjiahe-type exacerbated coarse-grained equal granodiorite.The figure provides the geological basis for the study of granite rheology.(2)The observation of the interior structure reveals that the shear-phase granite develops a S-C deformation fabric and consists of biotite,amphibole,feldspar quartz and other minerals;the potassium feldspar speckles in the extruded phase granodiorite are in a conjugated distribution,and the dark-colored minerals develop a northwest flowline;Quartz,feldspar,and mica in the extensional granite are evenly distributed,with no obvious directional magmatic joint structure.These understandings actually suggest theidentification of the rheological structures of the extrudate,shear-phase,and extensional rocks.(3)New insights into the stress field characteristics of controlled alteration belts in fault zones.Through the geological survey of the mining area,it is found that the phenomenon of altered mineralization in the area is very obvious,and has the characteristics of gradual transition and mutual superposition.Most of the structural alterations are developed in the lower plate of the main fracture surface.The closer to the fracture,the higher the alteration strength of the lower plate,and the higher the gold content.The strain ratio of rock was measured by dynamic recrystallization statistics method of quartz particles.The dislocation density was used to estimate the differential stress values and the relationship between different alteration zones.The results show that the strain ratios far from the fractured rock and the structural differential stress values are lower.This finding provides structural basis for the zoning law of altered mineralization.Combined with metallogenic geochemical analysis,it is found that the best location of mineralization is related to the sharply changing section of stress and strain.