The Survey Of Metallogenic Geologic Condition Of Lead-zinc Deposit And Metallogenic Prediction With Synthesis Information In The West Of Guizhou

The lead and zinc resource are the kinds of mineral that are mainly researched in《Mineral Resource Guarantee Engineering》of Fifth Plan made by TerritorialResource Department and are also the important mineral resource in Guizhouprovince. But over a long period of time, there is a saying for the Lead-Zinc Ore ofGuizhou, that is "full of stars and seldom of moon" and the Lead-Zinc Ore in thewest of Guizhou cannot be captured for a long time.For many years it has been difficult to find the mineral resources of more thanmiddle size in Guizhou and the methods that find a mineral resource basing on itselfcannot meet the current requirements for geological mineral examination. So it isnecessary to utilize the new theories and new methods as well as adopt the multiplemethods and synthesis formation (such as geology, geophysics, chemistry and remotesensing etc.).The west of Guizhou is the most important place for accumulating the mineralresources of silver, lead and zinc, and the site of it is at a triangle zone consistingwith a deep fructure of Xiao Jiang, in the trend of near north-south regionally, thedeep fracture of Mile-Shizong in the trend of east-north and the deep fracture ofZiyun-Yadu in the trend of west-north, which are all at a metallogenic belt of leadand zinc in Zhaotong-Liupanshui (Grade III). Above three deep fractures have thecharacters of multiphase activity and multiphase change. With the block character ofregional geochemistry, the anomaly of geophysical and the mineral assessmentresults of geologic full-dress investigation, it is showed that there are perfectgeologic background conditions for lead and zinc mineralizing in the west ofGuizhou and there would be possible to find a large size of lead and zinc mineral inthe area through strengthening the synthesis metallogenic information research anddeveloping the work measures.1, Metallogenci geologic condition analysisThrough utilizing the synthesis information data of areal geology, geophysicsand geochemistry in the west of Guizhou and with the analysis of metallogenicgeologic character and mineralizing geologic condition as well as the anatomy oftypical deposit, we have set up a metallogenic mode for the lead-zinc ore area innorth-west Qian.The metallogenic conditions of lead and zinc in west of Guizhou mainly are thatthe background of tectonic structure is in the fold belt of upper Yangzitian and nearto the fracture in the boundary of chasmic channel of Liupanshui;the conditions ofmagmatic rock are the basalt of Emei mountain, the distribution area of diabase andthe outsider of touch belt;the geophysics field is at a girdle and a magnetic gradientzone with north-south trend;the geochemistry field is at a zone with large content oflead and zinc in Weining-Shuicheng-Ziyun-Luodian;the horizon contributing tomineral mainly are Carboniterous System, and secondly Devonian System andPermian System;the type of genesis mainly is the low-temperature hydrothermalhorizon controlling with carbonate as a wall rock;The material sources come from asfollowing: the Palaeozoic horizon is as a mineral resource, and the natural watermainly is as a water source and the thermal source mainly comes from a heatquantity of mantle thermal plume and structure thermal. The main marks of findingmineral geologically are that the main thrust faulting of strong strain area structurallyand the borderland of secondary thrust faulting as well as the triangle top of strongstrain area are the main sector for controlling to form the mineral field, and theregional slipping surface and palaeo-solution cavity are main fields for controllingthe ore bed and ore body. The character symbols of geochemistry mainly are thatthere is a high anomaly of Pb and Zn in the sedimentary of drainage system, at sametime the high anomaly of Cd, Ag and Mo distribute in its center.2. The research of metallogenic prediction with synthesisinformationUsing geology as a prior premise, basing on summarizing and analyzing thebackground and geologic condition of mineralization systematically, utilizing the8metallogenic prediction theories and methods with the synthesis information, at sametime utilizing the relationship of the distribution between the orebeds of large-scaleand supersized and the orebeds of middle and small size, the mineral sites, salinitysites and anomaly dense-set areas to set up a mineralizing model and predictionmodel with syntheses information and try to find the large scale orebeds by aadvanced mathematical geologic and computer method to develop the synthesesinformation metallogenic prediction research concentrating on the west part ofGuizhou.In the paper, we have orientated and locally measured the anomalous concentratedareas of geochemistry components and the concentrated areas of orebed on the GISplatform, and developed the interpretation along with the linear and annularstructures of different depth layer, and have deduced that the buried basements andburied rock mass in the west of Guizhou mainly control the mineralizing of lead andzinc, which have provided the important evidences for analyzing the structure ofGuizhou Maintain areas, specially for analyzing the buried structure and geologicbody. We have concluded the major works and the obtained results as following:(1) Geologic interpretation with the gravity and aeromagnetic informationBasing on the characters of gravity and aeromagnetics and the structures of linearand annular that have been interpreted, as well as correlating with the basementmapping, the igneous rock and the anomalous geologic events with high, middle andlow temperatures components, we have obtained the following results: 1. the F1 faultinterpreted by aeromagnetic data, which trend is north-south to west-north, dividedinto two parts that the east part is a outcrop basement, the west one is a buriedbasement and the direction of basement is west-east;2.Having correlated the annularstructure interpreted by gravity data with the anomalous temperature components ofhigh, middle and low degree, it shows that some combination anomalies haveappeared regularly along the annular line, therefore we can deduce that those annularblocks are generated from rock bodys.(2) the powerful metallogenic analysis by basementIn the paper, we have analyzed the character of basement and circled the range andspace distribution of basement. In the west of Guizhou, there mainly are basements.The trend of basement bedding is the west-east and is divided into many blocks ofdiamond shape by a series of fractures with north-east trend and west-east trend. Wehave surveyed the powerful analysis of lead and zinc mineralizing by each basementunits through utilizing the theory of quantification Ⅲ, the method of R factoranalysis and character analysis, finally have divided the available metallogenic unitswithⅠ,Ⅱgrade of lead and zinc. The concluded rule that the basement controls themineral is that: The orebed basically distributes along the edge contact belt ofbasement or the abrupt belt of basement.(3) the research of rock mass controlling and its specializationThe method is interpreted by gravity data. It mainly crops out the buriedmid-acidness rock mass in the west of Guizhou province. We have divided theavailable metallogenic units of Pb and Zn ofⅠ and Ⅱ grade and have analyzed thecontrol factors. Then we have correlated the mid-acidness rock mass withgeochemistry components of Pb, Zn and known orebed. We have concluded that themost of ore beds of Pb, Zn distribute along the edge of mid-acidness rock and thetransitional zone, which shows that the ore beds of Pb,Zn in Guizhou mainly are thehydatogenesis with middle and low temperature, the hydatogenesis of hightemperature is seldom. It is also showed that the mid-acidness rock mass is the mainthermal source and mineralizing source for forming above ore beds;(4) the powerful metallogenic research of linear structureIn the paper, we have divided the linear structure of lead and zinc in Ⅰ,Ⅱgrade. We have respectively correlated the linear structure interpreted by gravity dataand aeromagnetic data with the known minerals distribution of lead, zinc and theanomaly of geochemistry component, it shows that the linear structure interpreted bygravity data and aeromagnetic data play an important role in controlling the lead-zincmineral and the anomalies of component;(5)Editing the catchment basin and surving its metallogenic specializationIn the paper, we have edited the catchment basin and correlated it with theanomalies of orebed and geochemistry components, so as to arrive and orientate thedense area of orebed and the range of anomalous dense unit. We would optimize thefirst and second grade units of lead and zinc through estimating the metallogenicspecialization;(6) Orientation forecastWe have correlated the edited catchment basin with the anomaly of orebed andgeochemistry components of lead and zinc (the sedimentary of water system), thendivided the dense area and the anomalous dense unit of lead and zinc orebed throughutilizing the faulting structure as a boundary. It includes 12 dense areas of leadorebed with 21 anomalous dense areas;12 dense areas of zinc orebed with 20anomalous dense areas, at the same time we have optimized 13 first and secondgrade units of anomalous dense area of lead and zinc;(7)Quantitative predictionWe have selected the basement, the rock mass, the linear structures interpreted byaeromagnetic data and gravity data, catchment basin, the predicted unit area and thecomponent anomalous area of lead and zinc mineral to be the geologic variable, andthen have picked them up and set assignment to them. We have also set up amultivariate regression equation through utilizing the application quantificationtheory Ⅰand multivariate regression analysis method to calculate the correlationparameters of lead and zinc mode ( independent variable) and have estimated theprediction amount of 9 anomalous units of zinc and the source amount of 7 modeunits.(8)dividing the metallogenic prospective area and synthesis evaluationWe have divided 6 prospective areas of lead mineralizing and 10 prospective areasof zinc mineralizing in the west of Guizhou.1. The prospective area character of Pb: We have predicted 6 anomalous denseareas of lead mineral with middle size in the west of Guizhou, which includes oneknown mineral area with an enlarging scale. They respectively are No.12, whichpredicted source amount is 140 thousand tons;No.21, which predicted sourceamount is 150 thousand tons;No.22, which predicted source amount is 260 thousandtons;No.23: which predicted source amount is 140 thousand tons and No.24, whichpredicted source amount is 100 thousand tons. The known unit of orebed area isNo.100011, which known reserve is 30 thousand tons and predicted resource amountis 110 thousand tons;2. The prospective area characters of Zn : we have predicted 10 anomalousdense areas for searching for the zinc mineral with middle size in the west ofGuizhou, including one known orebed area with enlarging scale;they respectivelyare No.22, which predicted resource amount is 380 thousand tons;No.30, whichpredicted resource amount is 140 thousand tons;No.31, which predicted resourceamount is 140 thousand tons;No.32, which predicted resource amount is 13thousand tons;No.25, which predicted resource amount is 130 thousand tons;No.16,which predicted resource amount is 100 thousand tons;No.17, which predictedresource amount is 130 thousand tons;No.13, which predicted resource amount is170 thousand tons;No.14, which predicted resource amount is 250 thousand tons.The known unit of orebed area is No.100011, which known reserve is 30 thousandtons and the predicted resource amount is 150 thousand tons.3. The analysis of synthesis evaluating factor:Basing on the predicting work for mineralizing, we have concluded that themain control factors of mineralizing are the side of mid-acidness rock mass and itsrock contact belt, the contact belt of basement and cover rock, the edge of buriedbasement, the inverted sequence structure, the Moho buried abrupt belt, Bouguergravity anomaly gradient belt etc. After having correlated with the mid-acidness rockmass, buried basement and each cover layer, most of them are at the edge of first andsecond grade mid-acidness rock mass, the contact belt of buried basement and coverlayer or rock mass.