| The eastern part of Yanbian area in Jilin Province, is an important gold andpolymetallic metallogenic area of mineral resources, which is rich in variety of mineralresources, mainly the production of gold, copper, lead, zinc, tungsten, molybdenum, ironand other minerals[2]. The gold and copper are dominate mineral resources with greatpotentials in the area, the known deposits and mineralization points give a widedistribution.In2008,Jilin Provincial Department of science and technology want toaccelerate and improve the utilization and development of gold and copper,establish thegold and copper mineral resources prediction project and carry out a systematicalresearch.1. Comprehensive geological data[1]The eastern part of Yanbian area in Jilin province,located in the circum of Pacificregion and Xingkai[2],experienced the development stage of circum Pacific tectonicdomain and of Asian tectonic domain.The geological conditions in the area exposed strataare complex,including Paleozoic,Mesozoic and Cenozoic,the Paleozoic strata.Intrusiverocks of granite in the area of are more developed[2].Main volcanic rocks is volcanic activity in Mesozoic Cenozoic, which is erupted inthe center-type along the fault zone and the depression basin and in fracture-type volcanicapparatus and volcanic rocks (Xuan Wuyan) platform.The main fault zone is in WangqingNW–to the fault zone, the old black-Yanji NE fault zone, five road ditch vernalization NE faults, all of which play a key role in the fracture of the tectonic evolution, controllingrock and basin,precious metals and mineralization of polymetallic[2]. Typical foldstructures of the area are Wudaogou syncline and small cap ridge anticline.2. Geochemical interpretationWe use sediments of chemical elements within the region to carry out statistical theanalysis, select15kinds of metallogenic elements related to gold, copper.By the analysison these15elements, combined with the geological conditions,we analyze the regionalmetallogenic conditions of gold and copper to dig out deeper geochemical information.First,from the perspective of geochemical parameters,we get the conclusion thatAu,Cu elements as discrete elements are rich in the study area.In the area, combination ofAu, Cu activity related to the formation of mineral are anomaly,namelyAu,As,Ag,Cu,Bi,Sb and W,Cu,Bi,Mo and other elements formed complex structure,large–scale composite anomaly.Finally, by using the stream sediment data to explain Au, Cu and other13elements,analyze the chemical characteristics of Au,Cu, and calculate the abnormal lowerlimit of Au and Cu are1.77×10-9and26.62×10-6respective.Gold anomaly is mainlydistributed in the middle of the studying area located in the Panhandle,north of Yanji,Montenegro and Hunchun old transition zone and the eastern region of Hunchun,withzonal distribution in space to things as the main direction of abnormal Au.Au has thecharacteristics of irregular shape,sizes and abnormal low.The abnormal distribution ofcopper in the study area,East and West,East North in zonal distribution, abnormal sizedifference.3. Geophysical interpretationThis study uses the data from gravity and aeromagnetic survey results, the accuracyof which is1:250000. The analysis and reasoning is based on the geological structure,strata, magmatic rocks,etc.,such that we can get deeper understanding of the geologicalinformation in the area,expanding the area of gold and copper production capacity ofinformation,so as to improve the quality of the evaluation results.In the gravity and magnetic survey,Regular changes happened on the observation value with different observation height of different magnetic density ofbody.According to the qualitative interpretation,the upward continuation height are200meters,500meters,1000meters and5000meters.And calculating on the first orderderivative and vertical two order derivative in four directions of0degree and45degree,90degree and135degree. Then by using the "association"principle based on those resultsalong with the regional tectonic interpretation,we achieve the reasoning on tectonicinferences from gravity information, which shows North East fracture is moreprominent,North East fracture zone,the characteristics of the typical representative ofTumen-Luo Zigoufault zone is the depth of cut and extending far.The traces, in other directions is small-scale but density,show the faults in east-westoriented features.4. Analysis on typical depositsStudying on geological characteristics of typical deposits in the study area tounderstand and master the geological conditions,which lay a solid foundation for theconstruction of geological concept model of ore deposit and play a controlling role in theformation of the deposit．This study on Ciweigou deposit,Xiaoxinancha gold deposit, the Nongping Audeposit,Naozhi gold and silver copper deposit is a representative, analyzes thecharacteristics of the study area, gold copper metallogenic background, geologicalcharacteristics, mineralization, mineralization, sums up the study of gold,copper orecontrolling conditions for the Cambrian-Ordovician strata,faults,Yanshan intermediateacid intrusive rocks and geochemical anomaly area.5. Analysis of metallogenic conditionsThe important content of this study is analyzing on metallogenic conditions of goldand copper,which laid a good foundation for the prediction of mineral resources andprovide a guarantee for the credibility of prediction results.From the research, we obtainedthat tectonic units,strata,structure,magmatite geochemical and geological conditions in thestudying area play an important controlling role in gold copper deposit.The researching area lies in the environment among two depressions and a long uplift [3]and the rift units was separated by the regional fault zone.The uplift is known as theMudan Ling–Chunhua broken region is expanded in east-west direction.To the north ofDunhua-Du Huangzi fault zone,to the south is Xinhe-Madida fault zone.It has been foundthat the expensive and polymetallic ore deposits (points),mineralization points aredistributed in the range of long break zone confined in[2].The distribution characteristicsproved that there is a close relationship between tectonic units and mineral.The fracture structure in the area play a controlling role in the distribution of gold andcopper by direct or indirect effects, where the indirect effect is controlled by the tectonicmagmatic activities and the activities of spray and he direct effect is controlled by fracturestructure,The distribution rule in the known ore deposits (points), mineralization is a NorthEast belt,North West into the distribution of three rows and four columns;known deposits(points) and mineralized points distributed in the intersection of fracture zone orfault,which embodied characteristics of faults controlling on the gold and coppermineralization.Such as mineralization concentration area of Xiaoxinancha,Madida-Nongpingarea,Ciweigou,Naozhi and FiveStars Mountain are all controlled by different levels offaults from east to west,north to east, north to west and north to south[2].The faults of the area not only provides a channel for migration of ore fluid,but alsothe precipitation sites for the precipitation of ore-forming substance.The formation is not only the geological ore formation,some also provides the sourceof ore-forming materials of gold and copper deposits.There are many obvious differencesbetween the period of dew formation and gold and copper mineralizationactivities[2],where the main ore bearing strata were from the Cambrian Ordovician periodof Wudaogou group,Permian Triassic liberation Village and Daxinggou group[2,4].In the researching area,the rock activities are the late Yanshan stage,when thedominate are acidic intrusive rocks,the direct source of gold and copper mineralization,onouter contacting zone which produced gold copper ore.The high background field of element gold,copper is an important symbol ofgold,copper ore.The gold,copper in high background field,such as Xiaoxinancha, Nongping Au,Naozhi,accounted for90%of known origin.The abnormality of gold andcopper is characterized by high strength,large scale,highlighting the center.6. Prediction and assessment of mineral resourcesThis study uses clustering analysis,correspondence analysis and quantitative analysisand grey correlation analysis,grey cluster analysis mathematical model to estimate of goldand copper deposits metallogenic prediction quantitatively,realized the prediction on theposition of gold and copper deposits.Among the31geological units,7in grade A,6ingrade B,10in grade C and8in grade D．7. Prediction results(1)Collected the information on the land,mineral resources and ore systematically,which provide the preparation for carrying out the mineral geological work.(2)For the first time,we explain the data on the gravity and magnetic on the basis ofthe principle of aeromagnetic,and get to know the geological characteristics from theperspective of geophysical,where the reasoning results on gravity and magnetic in thefaults has the enlightenment function on the understanding of Mesozoic Magmaticactivities,snow mountain rock and the relationship between mineral resources.(3)We re-know the geological history of the studied area by the theory and method ofgeodynamics,divide the development stage of paleo Asiatic tectonic domain and of thecircum Pacific tectonic domain and summarize the relatively independent evolutionaryprocess in each stage of development,but the latter played a strong transformation roleon the geological record of the former.(4)Divide the gold deposits into three types by the ore components in this area on thebasis of the study on a typical deposit.With the known ore deposits as the goal,the application of information correlationmethod,we analyze the ore controlling conditions and metallogenic elements in this area toestablish the gold (silver,copper)deposit in the comprehensive information prospectingmodel.(5)We chose27geological variables and realized the mathematical transformation ofwhich by the way of taking values under the guidance of the analysis on comprehensive prospecting model and ore controlling conditions.(6)We checked the prediction results by field investigation and collected39samples,where the testing results on Au and Cu of5have significance to ore prospecting.(7)we proposed advice on the arrangements for further exploration of gold andCooper deposits in the region and circled4future districts as the recent chosenprospecting minerals. |
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