| The Pb,Zn,Cu multi-metal—barite ore deposit of western Dayaoshan, Guangxi is locating in Guizhong basin, western of the Dayaoshan mountain, which is one of the most important exploration area of "The Tenth Five Years Plan"of Guangxi. Eventhough, the study of metallogenetic mechanism and new technology for ore prospecting and forecasting in this area is fall behind, as a result, the ore exploration in this aera have got little achievement since the finding of Panlong Pb-Zn deposit in 2003. So, based on field work and room study, this paper analyzed the minerogenetic mechanism, and then built the mineralization model for this area, generalized the major ore constraints, summarized the metallogenetic law, at the last, we have also did some mineral resource prediction and assessment (MRPA) for this area in GIS.There are many wording for the metallogenetic mechanism in this area, after studied many literatures, we found all these wording are focusing on two respects:①Someone thout the ore in this area was mainly controlled by stratum, and the ore was forming in mid-low temperature water sedimentary and then reformed by later hydrothermal,the main mineral resources are galena,sphalerite,barite;②While the others hold the point that the ore was mainly controlled by deep faults, and the ore was forming in hydrothermal silting these fault and cranny,so the main mineral resources are galena,sphalerite,chalcopyrite,barite and so on. In these, based on the ore forming setting analysis,this article have discussed the stratum,lithology,structure,hot water sedimentary rock and the epigenesis after deposition,at the end,we have cited a typical ore deposit to explain the analysis. A great many exposition have made known that the ore in this area have the three ore controlling factors "source,fill,cover" to an organic whole and three ore forming laws" stratum,face,position"to an organic whole character.To the mineralization, source bed +dolostone,biological fossil bearing carbon limestone and crush belt between layers+mudfish or mud-bearing stone have beening constituted to form the three ore controlling factors "source,fill,cover" to an organic whole. While to the mineralization laws,ore contained stratum+ sedimentary face+ constructive position have beening constituted to form the three ore forming laws"stratum, face, position" to an organic whole.There are five kinds of hot water sedimentary rock,they are barite, silicolite, ferrodolomite, secondary layer silicolite, nodular chert limestone,the study about their distributed,occurrence,forming environment and the rock geochemical character have prove that they have formed in a wide ranging hot water sediment event,and therefore formed the hot water sedimentary buildups barite-silicolite-ferrodolomite-secondary layer silicolite-nodular chert limestone in the Xiangzhou fault basin,there are strong relation between the hot water sedimentary buildups and the ore deposits,the hot water sediment event have played a important role in the ore forming course.As a result,this paper hold the opinion that there are three types of ore deposit in the study are,the first type is the syngenetic Pb-Zn-multi-metal—Barite ore deposit formed in the sea floor hot water sedimentent, the second type is the stratabound Pb-Zn-multi-metal ore deposit formed as the hot brine evolution in the fault basin, while the third type is the structure-constrainted Cu-multi-metal—Barite ore deposit formed as the hydrothermal silting these fault-cranny and reactived with country rock. The ore-forming matters mainly came from Devonian and Cambrian stratum, some portion came from deep magmatism; The ore-bearing fluid came from the seawater and rainwater, which infiltrated follow the deep faults and been heated in the deep, but there was still deep fluid mixed into the ore-bearing fluid.The heat mainly came from the terrestrial heat and magmatism.At different region or different type of ore deposits have different ore forming temperature, overall, the Pb,Zn,Au deposit in the northern part has the ore forming temperature 181—230℃, while the Pb,Zn,pyrite in the southern part has the temperature 135—197℃.We have did the valley's secondary soil geochemical prospecting at the scale 1:25000 in some parts of this area systemly, meanwhile, we have collected 1:50000,1:100000 soil geochemical data this area systemly, then we larged the 1:25000 soil geochemical data's scale to 1:50000 or 1:100000, and then did some revise to the data we collected using these data, at last draught the anomaly map again. This article would select the main ore-forming element to state the soil geochemical character. On the whole, we found the soil geochemical has some characters as the following:①The Au,Cu,Ba,Zn,Pb anomaly is very obvious in silicification area, while the Zn,Pb anomaly is very obvious in limestone area, and the Au,Ag,Cu is very obvious in silicolite area;②The Ba anomaly is very widespread, especially in silicification area, while in the "Guanqiao formation" in limestone area, the Ba anomaly is also very widespread, and the Zn takes second place;③There are mainly two types of elements group in anomaly, one group is the Ba-Zn-Pb while the other group is the Ba-Cu-Au;④From north to south, there are some laws in the elements grouping, that is they have such grouping from Cu-Au-Zn-Pb-Ba-Ag to Ba-Zn-Pb-Cu to Pb-Zn-Ba as from north to south。Beside, we have stated the geophysics character in our study area simply.Based on these knowledge, we summarized the mineralization law in our study area. At the time of mineralization, the minerogenetic began as the low Devonian forming, and then in the "Guanqiao sedimentary"of low Devonian, there came the hot brine minerogenetic as the Xiangzhou fault basin had already formed, most of the deposit in our study area had formed in this time.And at the Yinzhi-Yanshan period, this area had undergone great tectonic movement and magmatism, the ore deposit had been reformed, and the nervation of Cu,Pb,Zn had arised. In the space distribution, the tectonic setting determined the ore deposits distributed, the source bed and the interface of layers determined the ore-bearing stratum, while the mini-structure,hot water deposit,alteration and minerogenetion had determined the ore body's location mineral's grouping and zoning.In the mineral grouping, metallogenic specialization and heritage, as well as the tectonic setting and metallogenic geology condition determined the ore types and mineral grouping.At the last, we have built two kinds of mineral resource prediction and assessment model, No.1:to the strata-bound Pb,Zn,pyrite and barite deposit; No.2:to the hydrothermal Cu,Pb,Zn,Au and barite deposit. According to the two MRPA model, we abstracted geology variances and evaluated each of them, revised them by expert commentary, and then sorted them according the benefit to mineralization each geology variances did, at last we calculated the weight of each geology variances in every forecast grid and generated the map for the preferable ore-finding area.After that work, we have defined four probable ore-forming area, they are Dongxiang-Tongwan Pb,Zn,pyrite probable forming area, Shuicun-Dongxiang Pb,Zn,Cu probable forming area, Toupai-Sicun barite,Cu,Pb,Zn probable forming area and Guchang-Longjiang Cu,Au,barite probable forming area, Meanwhile, we have also defined thirteen preferable ore-finding area, among them, the A grade is four,B grade is four,and C grade is five.After this study, we got the conclusion as following:①There are three types ore deposit in western Dayaoshan, the first type is the syngenetic Pb-Zn-multi-metal—Barite ore deposit formed in the sea floor hot water sedimentent, the second type is the stratabound Pb-Zn-multi-metal ore deposit formed as the hot brine evolution in the fault basin, while the third type is the structure-constraints Cu-multim-metal—Barite ore deposit formed as the hydrothermal silting these fault-cranny and reactived with country rock. Among them,the second type is very widespread in our study area,and so it is the main type we should pay great attention to in our exploration.②The hot water sedimentary had played a important role in the metallogenic, they have strong relation between the ore deposit in space distribution and genesis, and the characters is very obvious and stable.While in the past ore exploration and study in this area, we payed little attention to the hot water sedimentary, so we should realize the importance of the hot water sedimentary and do some stud, we may make great progress in our exploration unexpected, it is also one of the most important step to go away from the traditional exploration thinking in this area.③There is a very typical character that the ore in this area have the three ore controlling factors "source, fill, cover" to an organic whole and three ore forming laws"stratum, face, position"to an organic whole character.④The ore indication and ore-finding sign is very clearly in the preferable ore-finding area, the ore-forming condition is good, there are many ore deposits and mineralization outcrops in the preferable ore-finding area too, meanwhile, most of this area have skin-deep exploration, so if we have the right theory and better technology, there is no doubt that our exploration will make great progress in this area.
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