The Synthetic Informational Prognosis Of Metallogenic Prospecting And Volcanic Mineralization Of Longbohe Copper Deposit In Jinping County Of Yunnan Province

Demand of mineral resources grows increasingly in China, with the rapid development of economy. However, the guarantee of major minerals resources is quite low, and situation of supply for mineral resource is quite severe in China. In this case, in order to ensure economic safety, high-efficient, continuously developing of our country, we should discover more mineral resources of varieties and type, depending on the scientific and technological progress, with the effective modern mineralizing theory and prediction.Copper resources has been lack as one of mineral resources of our country long-term. It has become a hotspot of the mining for our country to seek those mineral resources of lack. Since our country carried out the stratagem of west development, the mining has become the key industry of Yunnan province, and the new upsurge of geological research and mining exploitation have appeared again in Yunnan province. Longbohe copper deposit locates the southeast region of Yunnan, its region geo-structure position is in the Red River suture line connected with the Yangzi tectonic plate and the QingZangDian tectonic plate. The mining area may be divided into two ores zones bounded Red River fault. The mineralization of east ore zone lay in a suit of low metamorphism volcanic rock series, and the mineralization of west ore zone lay in the AilaoShan group deep metamorphism rock series.The doctorate dissertation , The volcano mineralization and the comprehensive information metallogenic targeting of Longbohe copper deposit in Jinping county, Yunnan Province, is based on national territory resources major key investigation project of Chinese geology Investigation Bureau《Yunnan JingGu-JinPing area copper mine appraisal》( serial number of project: 200010200112) and the " The tenth five years plan" key area zone project of the Nonferrous Geological Bureau in Yunnan Province《The prospecting appraisal of Jinping - Yuanyang - LuChun area gold- copper polymetallic deposit in Yunnan province (serial number of project: 2002-011). It aims research at costal part of the mining and the geological survey of our country, using the volcano mineralization theory and the synthesis information mineralization forecast method, to carry out the research of the synthetic information metallogenic prediction in Longbohe area. Carried out widespread field geological investigation and inside synthetic research, under the investigation and research results of the predecessor ,the author has gained the following main achievements:1 The theory achievement1.1 To Summarize overall systematically regional geological condition first time, and study synthetically metallogenic geological background related with the many kinds of genesis deposits in this area, and point out that they are the product of the different stages geological evolution in the united geo-structure background.1.2 By mineral compages, the low metamorphic volcanic rock series consist of the metamorphic andesite, metamorphic sub-volcanic rock and metamorphic base volcanic rock in east ore area of Longbohe copper deposit. In the categorised diagram of geochemistry, the samples of the low metamorphic volcanic rock series mainly lie in the area of alkaline basalt, so the rocks should be most a set of sodic-rich and alkaline basalt series. The discrimination diagram of the different tectonic environment basalt reveals that basalts belong to a intraplate basalt environment. Various geochemistry evidences indicate that the basalts are results of the homologous magma at different evolvement stages. Their primary magma is the result of metasomtic and enriched mantle melting in the tectonic environment of the continental intraplate setting. The fractional crystallization has important position during magma evolution. Their formation relate with plate dive, magma upwelling and draw function. We also proved the era of this low metamorphic volcanic rock series is not Triassic, but is Meso-Neoproterozoic, and confirm its age as 1,600 million years. 1.3 This article summarized the geological characteristic of the deposit in detail, classifieded reasonably and newly the deposit, studied the metallogenic types, and established the metallogenic model. East ore zone includs four kinds of metallogenic types: the metamorphogenic base volcano rock type, the metamorphogenic volcano-hydrothermalism type, the hot water sediment deposit and the structure crushed zone type. They have the metallogenic model of 5 floors and a ladder. West ore-zone includes three kinds of metamorphogenic types: contains copperish magnetite type, copperish pyrite sediment and metamorphosed rock type, the quartz pulse type.1.4 Stable isotope research of the deposit indicated : Sulfur mainly comes from volcanic rock; lead is basically in normal lead scope; metallogenic matter comes from the mix source of lithosphere and the upper mantle. The metallogenic solution is mixed flow of magma water, subterranean heat bittern, metamorphogenic water. Researching geochemistry characteristic of the fluid inclusion, metallogenic fluid is considered as middle temperature, middle-high salinity, and middle-high density which belongs to the high metallogenic Na⁺ - Ca²⁺ chloride type. Temperature, salinity, pressure in volcanic and sediment metallogenic period is higher than that in hydrothermal and modified metallogenic period.1.5 Concept of comparison deposit is handled first time to contrast with Longbohe copper deposit and some typical, similar domestic and foreign deposits. It not only enriches metallogenic theory, develop prospecting thinking, but also has important strategic significance to the regional prospecting and the researching.â‘ Contrasting between the east ore zone of Longbohe copper deposit and Dahongshan iron-copper deposit, remarkable research results are obtained, prospecting thinking of iron and copper is broadened in the ore area and the region. The research proves: the low metamorphic sodium volcanic rock series extend to north-west; the two deposits resemble each other in combined character of rock, lithology, petrochemistry, geochemistry, form era and character of main microelements and isotope. The comparability makes this area to become the most advantaged area to discover Dahongshan model iron-copper deposit. The two mineral deposits are also extremely similar in the mineralized types and the structure environments, and both belong to the metallogenic and volcanic massive sulphide deposit.â‘¡The west ore zone of Longbohe copper mine is much similar to Shengquan copper mine (Vietnam) in character of lithology, structure, magma and mineralization. The two mines are considered as products of the different zone and the same lithofacies. So there is prospecting potential to explore big copper deposit of Vietnam shengquan model in the west ore zone in Longbohe copper mine, and it is possible to explore huge potential ore bodies in deeper of the west ore zone in Longbohe copper mine.1.6 By the exploration and research recent years, we analysed ore-controlling factors, and basically found out metallogenetic law and places of occurrence of rich and big ore bodies. We general concluded all kinds of ore prospecting indicators, and established the controlling model and the metallogenetic model of deposit. The controlling model is two faults to nip one anticline in the east ore zone. The two faults are Honghe fault and Alonggu-Longshan fault, and one anticline is Longda(south) or Laoxinjie anticline(north). The controlling model in the west ore zone is the metallogenic geological bodies, the join of two faults, and the interlayer fracture zone. The metallogenetic model can be concluded as environment of taphrogeosyncline, sedex, hydrothermal superimposition and structure reworking.1.7 At first, we introduce the volcanic metallogenetic theory and the hydrothermal sedex metallogenetic theory to the research of deposits in the ore area. We propounded a new academic cognition about deposit genesis. We consider Longbohe copper mine as a middle temperature , composite polygenetic deposit of the metallogenic volcanic sedex, hydrothermal superimposition and reworking, late tectonic reworking. Metallogenetic time extended form Meso-Neoproterazoic to Mesozoic. Form time of the original copper deposit is approximate 1650～1750Ma, then the original copper deposit suffered from reworking of Jinning movement, Yinzhi movement, Yanshan movement and Xishan movement. Metallogeny has characters of the long term, multi-stages, multi-source, multi-phases, multi-genesis.1.8 By exploration and the practice, we present a new prospecting technology thought. In the east ore-zone ,it is generalized to trace stratum and lithology→to identify volcanic organ→to distinguish ore-bearing structure→to seek for wall-rock alteration→to check the anomaly of geophysical prospecting, geochemical prospecting→to put engineering means in practice . In the western ore-zone ,it is conclude to explore the advantaged stratam (Wudoukeng formation of Ailaoshan group )→to identify the best ore-containing structure(the north-west reverse fault)→to enclose the felsic dikes→to observe the mineralized and altered evidence→to carry out the geophysical and geochemical exploration(the magnetic method and the electrical method )→to evaluate anomaly→to verify.1.9 Presenting circle principle and divisiory reason of metallogenic prognosis, we carried out the metallogenic prognosis with synthetic information in this ore area, and then pointed out prospecting direction, selected 10 prospecting targets. They are four I level prospecting targets, three II level targets and three III level targets. Finally, we has pointed out that Longbohe copper deposit is a big copper deposit associated iron and gold, and put forward proposal for next step prospecting work deployment to the geological production department.1.10 It is one of innovation for the article to discovered gold ore body(mineralization) and thulium mineralization in the study area, to which special attention should be caused.2 Methods results The outstanding achievements were obtained by applying various methods and means to carry out systematical research and integrated technologies to the topic .A comprehensive model of the geological exploration is built on the first time on the basis of synthesis of geological prospecting model, geological-geochemical prospecting model , geological-geophysical prospecting model and geological-remote sensing model, etc. These models can provide some scientific foundation for the metallogenetic forecast in this area and give methodological guide on searching for the same type of deposit. Practice has proved that the organic optimum of geology, geophysical prospecting, geochemical prospecting, remote sensing and drilling methods are effective on ore -prospecting, which can find more industrial ore-body. Simultaneously, experience on organization and management are gained in the process of study.3 The appliance effective and reserves results3.1 The three optimized prospecting targets obtained by applying the comprehensive model were provided to the production department during the study .With certifications by pit and drilling test ,one copper deposit, two iron deposits and one gold mineralized site are founded lately. The newly increased 334₁ copper resource are 200,800 tons, the prospecting results are very good. Furthermore, in the whole deposit area, 333+334₁ copper resource can be estimated to 1,000,000 tons.3.2 In the eastern ore-belt of Longbohe copper deposit ,333+334₁ copper resource are 412,838 tons totally with the 1.47% average grade, the data has been investigated and checked by CGSB (China Geological Survey Bureau). The latent economical value of the deposit costs more than 28,000,000,000 RMB.