| Since the 1970 s,a large number of epithermal gold deposits have been discovered in the Pacific Rim.The epithermal gold deposits have not only become the focus of research,but also become one of the important types of gold deposits.However,Xiaoxing 'anling is located in the western belt of the circum-Pacific metallogenic belt.Since Mesozoic,it has been subducted by the Pacific Rim and has provided a good power source for mineralization.The eastern part of Yidong Linchang is located in Xiaoxinganling-Zhangguangcai ling magmatic arc and Yichun-Yanshou magmatic arc.The Eastern Yidong Linchang gold deposit is located in Xiaoxinganling-Zhangguangcailing polymetallic metallogenic belt,which is one of the important metallogenic belts in Heilongjiang Province.The northern part of the belt is Xiaoxinganling gold concentration area.In recent years,large gold deposits such as Dongan gold deposit,Gaosongshan gold deposit and Wulaga gold deposit have been discovered in the area.There are Daxilin iron deposit and Xiaoxilin lead-zinc deposit in Yichun city in the south of Yichun city,which indicates that the eastern part of Yidong Linchang has favorable metallogenic geological conditions and good metallogenic prospects.The main manifestations are:Regional stratigraphic characteristics: The volcanic rocks of the Banzifang and Ningyuancun Formations of the Lower Cretaceous are mainly rhyolite,andesite and pyroclastic rocks.There are large area of Lower Cambrian old Taomiao high group,Yanshan formation and middle lower Ordovician Bao Quan formation.As the old basement,the Palaeozoic and lower Cretaceous strata have high gold abundance.Regional Tectonic Characteristics: The tectonic location of Yidong Linchang area is located in Xiaoxing'anling-Zhangguangcailing magmatic arc and Yichun-Yanshou magmatic arc.The region has undergone two major stages of tectonic development(paleo-Asian Ocean marginal accretion and evolution stage,and littoral Pacific continental margin activity stage).The frequent magmatic activity and strong tectonic activity in the region provide sufficient magmatic and tectonic conditions for regional mineralization.Characteristics of regional magmatic rocks: Late Triassic granite diorite,monzonite,alkali-feldspar granite and early Cretaceous granite are exposed in the area.According to 15,000 ore survey,the Late Triassic granite is closely related to Mo,Fe,Cu,Pb and Zn deposits,and the molybdenum deposit in Southwest Shannan has been found in the south of the study area.The late three Permian two granite and early Cretaceous granodiorite are closely related.The Eastern Yidong Linchang gold deposit is hosted in the intermediate-acid volcanic rocks of the Lower Cretaceous Ningyuancun Formation and Banzifang Formation.The NNE trending structure is an important ore-controlling and conducting structure.Au mineralization is associated with low-medium temperature hydrothermal alteration types such as silicification,clayization and pyritization,and is a medium-low temperature hydrothermal gold deposit.Based on the study of regional geological background and metallogenic geological conditions in the eastern part of Yidong forest farm,combined with the geophysical and geochemical exploration results of 1: 50000 and 1: 20000,and according to the engineering verification results of trench exploration and drilling,a grade I metallogenic prospect is delineated.Gold ore bodies occur in the contact zone between the Lower Cretaceous Banfang Formation and the Ningyuancun Formation volcanoes,where silicification,pyritization and carbonation are developed,and regional NNE trending structures and magmatic activities are intense,providing ore-guiding,ore-hosting and heat-source conditions for their mineralization.Ten gold ore bodies and many gold mineralized bodies have been discovered during the preliminary engineering verification,including two industrial grade gold and silver ore bodies,which fully shows that this area has a good prospecting prospect. |
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