(1) Incorporate ore deposits into rocks and ore-bearing geological bodies into structural unit evolution, and carry out research work from a systematic perspective. In terms of research ideas, starting from the geological distribution of important magmatic sulfide deposits and massive sulfide deposits in the world, this paper summarizes their metallogenic characteristics in time and space, compares the types and geological distribution of magmatic sulfide deposits and massive sulfide deposits in China and the world, and summarizes the metallogenic characteristics of two important deposits in China. On this basis, the metallogenic characteristics of magmatic sulfide deposits and massive sulfide deposits in Qilian Mountain are studied, and their metallogenic regularity is explored.
As a special rock with important utilization value, ore deposit is the product of geological process under certain conditions. A certain geological structural unit will inevitably produce various interrelated branching actions in a certain tectonic activity process, and form a mineral deposit metallogenic combination which is most closely related to a specific geological process in different geological parts. The complete process of continental cracking, ocean basin appearance, subduction and tectonic convergence from late Neoproterozoic to early Paleozoic in Qilian Mountains formed different metallogenic responses. For example, massive sulfide deposits related to continental rift, island arc rift and back-arc spreading ridge (represented by Baiyinchang, Langlike and Xuequan respectively), skarn tungsten (copper and molybdenum) deposits related to active continental margin (represented by Xiaoliugou) and low-temperature epithermal precious metal deposits (represented by Hanshan), and sandstone copper deposits related to foreland basin after structural convergence (represented by Tianlu). According to the similar complete metallogenic system, it is predicted that porphyry copper (molybdenum) deposits should be formed in the active continental margin and mature island arc environment, but so far it has not been found that there are no important conditions for forming such deposits, or it may be caused by inadequate exploration work. In any case, the metallogenic system is only a systematic view, and the metallogenic combination and intensity are different due to the differences of geological conditions in different regions and times. But from the research point of view, it can provide an exploration idea. This book focuses on the study of specific deposit types and the possible genetic forms of similar deposits in different microfacies.
(2) The similar deposits of adjacent tectonic units are integrated into a system, and the research work is carried out from the perspective of connection. Among the successful examples of world exploration, there are many successful examples of selecting the target area by using the connection viewpoint to study the metallogenic background and metallogenic conditions. This is a geological correlation method widely used in today's prospecting and exploration, and it is a related metallogenic viewpoint. For example, by comparing the geological background of Zambia's super-large copper deposit, the super-large uranium-copper deposit in the Olympic Dam of Western Australia was successfully explored. The continental rift basalts of Lake Superior 1Ga in Wisconsin in the northeastern United States are also compared with the continental overflow basalts in Norilsk, Russia and Voisey Bay, Canada, and it is considered that they belong to igneous provinces with super mantle plume. The ultramafic rocks in Jinchuan area of Longshou Mountain and Lashuixia area of Lajishan in South Qilian Mountain may belong to the same large-scale magmatic activity, which is the practice of this study from the perspective of contact. The viewpoint of connection is also reflected in the close combination of deposit formation and basic geological research results. Using the achievements of supercontinent formation and cracking block transformation in geological history can provide new ideas for regional prospecting, and the discovery of mineral deposits can also be used as important evidence of continental accumulation and dispersion.
(3) Ore deposit science is closely combined with petrology, structural geology and geochemistry, and research work is carried out from a comprehensive perspective. For metal sulfide deposits closely related to magmatism, it is impossible to achieve in-depth results with a single research method of ore deposit science, which is also the development trend of contemporary ore deposit science research, fully absorbing the research methods and achievements of other disciplines and developing into a comprehensive discipline based on ore deposit science research. This book focuses on the exploration of regional mineralization, with special emphasis on the application of the latest knowledge of igneous petrography, trace element geochemistry, isotope geology, Precambrian continental reconstruction and regional tectonic geology, aiming at providing a new research framework for the metal sulfide deposits related to magmatism in Qilian Mountain, and trying to develop, supplement and innovate the previous research results.
This book selects two important types of metal deposits in a metallogenic belt for research, mainly focusing on the regional metallogenic research and regional prospecting potential analysis of the two types of deposits. The specific technical route is as follows:
(1) literature collection and analysis, and put forward the research focus. On the basis of predecessors' work, fully collect the existing literature and achievements, and further collect the latest relevant literature at home and abroad on the basis of comprehensive analysis and research. After comparative study, select the main content of the study and highlight the key points as the main research content.
(2) Carry out field work according to the implementation project. Based on the ongoing project work, the contents of field investigation are carefully designed, and field data are collected through route geological profile, large-scale structural-lithofacies mapping, special sample collection, etc., and field observation and research are carried out on adit exploration and stope of important ore bodies, and new problems are put forward by synthesizing the data.
(3) Revise the understanding and clarify the research ideas. Based on the comparative study of the comprehensive results of field data and previous achievements, this paper draws lessons from the new understanding and discoveries at home and abroad, and makes a comparative study with important deposits and metallogenic belts at home and abroad, forming a new research idea, which has been confirmed and improved in further field work.
(4) Deepen the achievements and improve the research outline. Write a special paper on the previous research results and new understanding results, further deepen the understanding and clarify the overall framework of the paper. While revising the monograph, gradually form the overall goal and research content structure of the thesis, and improve the outline of the thesis.
(5) Focus on key points and strive for innovative achievements. The soul of scientific research is innovation, and the source of innovation is repeated practice. After the research outline is clear, it is necessary to further collect information and carry out field work to make up for the weak links in the research and make the research results perfect day by day.
In the research work, the prospecting problems of these two types of large and super-large deposits are emphatically considered. Since the 20th century, with the rapid development of global economy, the demand for bulk metal mineral resources has developed rapidly. According to the statistics of the International Copper Association, in 2000, the global copper consumption reached 6.5438+0.52 million tons, of which China reached 2.5 million tons, accounting for 654.38+07% of the global copper consumption. At present, China has replaced the United States as the world's largest consumer of copper, and China needs copper. It can be seen that the prospecting task of China copper mine is arduous. The price of nickel ore in the world has rebounded, and the price of nickel in the international mining market has reached 12250 USD/ton. Nickel has become a global strategic resource, and the global enthusiasm for finding nickel ore has greatly increased. At present, most of the magmatic Cu-Ni PGE ore belts related to mafic-ultramafic rocks in China have been set foot in by foreign exploration companies, which also reflects the urgent demand for nickel ore prospecting in the world mining industry.
The world's largest magmatic nickel sulfide deposit, the sudbury nickel mine, is in deep exploration. Yingqiao Company redrafted the exploration strategy of the mining area from 200 1, trying to find a new ore body with a buried depth of about 1500m, which can be mined near the mining area. The exploration adopts a three-dimensional model and uses the electromagnetic anomaly data of previous wells. The borehole MAC- 100 constructed in 1996 was re-measured, and the EM system of UTEM No.4 well was used. Drilling confirmed that new sudbury contact zone mineralization, namely disseminated-intensive disseminated and massive pyrrhotite, nickel pyrite and chalcopyrite, was discovered in the south of the eastern margin of sudbury igneous complex. The mineralization width of footwall is 0.5~20m. At present, 4.6 million tons of ores with estimated resources have been controlled, including 2. 17% of nickel, 4.9% of copper, 2.6g/t of gold, 3.66g/t of platinum and 8.56g/t of silver. This is an important example of deep prospecting in the old mining area. As a world-class giant magmatic nickel sulfide deposit, Jinchuan deposit in the study area also has the problem of further prospecting, and this problem is becoming more and more important. According to the recent cooperation contract signed by Rio Tinto Mining Development Co., Ltd. of Britain and Chyi Chin Mining Company of Gansu Province, the two parties will jointly conduct risk exploration for Longshoushan copper-nickel mine in Gansu Province. Rio Tinto will use high-precision aeromagnetic survey to carry out risk geological exploration in an area of about 2000km2 in Longshou Mountain, Gansu Province, with a view to discovering new world-class copper-nickel deposits. The above-mentioned successful exploration examples and the actual demand for exploration encourage us to actively increase the research efforts to open up new prospecting fields in this area.
It is reported that the copper market in China is no longer elegant due to the exhaustion of mineral resources. At that time, the annual output of Zheyaoshan and Huoyanshan opencast mines reached more than 4 million tons, which can be described as "work at sunrise and rest at sunset". From 1956 mining to pit closure in the mid-1980s, the two stopes contributed 8 13000 tons of copper, but at present, the accumulated loss of Baiyin Company has reached 4.7 billion yuan, and the asset-liability ratio is 160. Looking for new mines and opening up new mining areas should be one of the ways out for silver. The research and exploration of Cyprus-type copper-rich deposits in North Qilian Mountains have important theoretical value and practical significance.
The research work of this book is based on the previous work. Mainly relying on the author's participation in the large-scale land and resources survey project "Prediction of super-large copper-nickel (platinum group) magmatic sulfide deposits in China (No.:20010200058)" (2001~ 2003) and the mineral resources compensation project hosted by the Ministry of Land and Resources "Investigation of Xuequan Copper Mine in Sunan Yugur Autonomous County, Gansu Province"
The project "Study on the Prediction of Super-large Cu-Ni (Platinum Group) Magmatic Sulfide Deposits in China (No.2001KLOC-0/0200058)" is a national Cu-Ni deposit metallogenic regularity and prospecting prediction project presided over by Academician Tang Zhongli. The purpose is to compare the background of Chinese mainland and the characteristics of mafic-ultramafic rocks with the metallogenic environment and ore-bearing rocks of world-class Cu-Ni magmatic sulfide deposits. The author was fortunate enough to participate in this project. The research focus of this project is to summarize the metallogenic characteristics of magmatic sulfide deposits in Chinese mainland, and to evaluate the metallogenic potential of Emei basalt in the western margin of Yangtze ancient land, small and medium-sized intrusions in the southwestern margin of North China ancient land and newly discovered mafic-ultramafic intrusions in the southwestern margin of Tarim ancient land. At the same time, the possibility of large magmatic copper-nickel sulfide deposits in the northern margin of Junggar landmass in northern Xinjiang (represented by Karatongke copper-nickel deposit), the southeastern margin (represented by Huangshan copper-nickel deposit), the northeastern margin of North China ancient land (such as Chibaisong and Hongqiling deposits) and the southeastern margin of the Yangtze River (Baotan Kemate magmatic nickel sulfide deposit) was discussed. Jinchuan deposit on the southwest edge of North China ancient land is the only world-class super-large magmatic copper-nickel (platinum-bearing) sulfide deposit in China, and it is also an area of concern for copper-nickel mineral exploration and researchers in the world. Since the discovery of this deposit, the geological work has basically never been interrupted. In recent years, British mining companies have carried out audio controlled source magnetotelluric sounding (CSAMT) exploration of deep-buried intrusions in the periphery. In order to make a further breakthrough in the prospecting of this deposit type, we need to make a further breakthrough in understanding. This book has made a positive breakthrough on this issue. Emei basalt in the western margin of Yangtze ancient land is the only large igneous province (Zhongdeng,1995; Xu et al, 200 1), can provide a research site for magmatic copper-nickel sulfide deposits in our province, but large-scale copper-nickel mineralization has not been found in this area. Mafic-ultramafic rock mass is newly discovered in the southwest margin of Tarim ancient land, and copper-nickel mineralized mafic-ultramafic rock mass was discovered in the comprehensive survey of mineral resources in West Kunlun in recent years, which should be the product of rift on the margin of Tarim ancient land.
"Investigation of Xuequan Copper Mine in Sunan Yugur Autonomous County, Gansu Province" is an exploration and research project under the guidance of Xia, the author, aiming at evaluating the prospecting potential and prospect of Cyprus-type massive sulfide deposits formed in the oceanic crust environment in this area. The clarity of the project itself urges the author to deeply study the metallogenic environment and genetic model of this kind of deposit, and review the regional metallogenic intensity and possible preservation methods under the regional geological background. The types of massive sulfide deposits in North Qilian Mountains were divided into two types in the past: massive sulfide deposits related to felsic volcanic rocks and massive sulfide deposits related to basic volcanic rocks. The existing industrial deposits are basically related to felsic volcanic rocks, such as Baiyinchang, Gadaban and Guomisi in Qingshuigou-Bai Liu Gully. Massive sulfide deposits related to basic volcanic rocks are only found in the east of Tiger Mountain, and there are 9 small deposits in the west, such as Quanshui and Gougou. In the research on the genesis of marine volcanic rocks and the prospecting potential of related minerals in Beilianshan during the Eighth Five-Year Plan and more than 950 years, Xia predicted that massive sulfide deposits related to tholeiite series in the back-arc expanding oceanic crust environment had important prospecting potential based on the identification and confirmation of residual tholeiite (Xia et al., 1996). The discovery of Xuequan (Shikuligou) copper deposit in Sunan, Gansu Province initially confirmed this understanding, but the prospecting prospect is still inconclusive, and the exploration work is still in progress. It is of great significance to study the metallogenic mechanism and ultimate preservation mode of the deposit. The existing work shows at least two metallogenic styles: one is that in pyroclastic rocks and massive basalts mainly formed by central volcanic eruption-overflow in the early stage of back-arc expansion, the spout of metallogenic hydrothermal circulation system was formed at the intersection of primary annular and radial fractures around the ancient crater, and the metal sulfide ore body formed was deeper than the plate ore body. The ore minerals are mainly chalcopyrite, pyrite and pyrrhotite, with a small amount of sphalerite, and sometimes the content of sphalerite can be higher than that of chalcopyrite, which is related to the metallogenic position. Porphyry rocks were found in the ore minerals represented by No.Ⅵ ditch in Curie ditch, Xuequan stone, indicating further enrichment and transformation in the later stage, so the Cu content can reach more than 30%, which is a typical copper-rich mine. The other is that in the typical submarine pillow basalt, the cracks formed by parallel spreading ridges or vertical spreading ridges form the jet system of hydrothermal circulation system, and the copper sulfide body with a certain extension is irregular. Therefore, there are two main types of mineralization: the initial stage of back-arc expansion and the mature stage. It should be pointed out that layered ore bodies can be formed when ore-forming fluids act on volcanic depressions.
The project "Study on the Prospecting Potential Evaluation of Jinchuan Copper-Nickel-Platinum Group Deposit in Lajishan Area, East Qinghai, China" is a scientific research project signed by Xi Institute of Geology and Mineral Resources and internationally renowned mining company Western Australia Mining Company (WMC) to evaluate the feasibility of exploration and evaluation. It is a prospecting idea proposed by the author to simulate the metallogenic conditions of Jinchuan copper-nickel deposit at that time and reshape the later structural transformation style. Magmatic sulfide deposits mainly have two types of ore: one is disseminated ore, which is generally considered as the ore formed by melting in magma chamber. The ore has low metal content, which is called Class II ore abroad, and it is unlikely to form a large-scale deposit. The other is sponge siderite (net) ore, which is molten (immiscible) sulfide in deep magma chamber or rock pillar and located at the bottom of magma chamber when it enters high position. Known as class I ore abroad, it is a necessary condition for large-scale mineralization. More than 90% of the ores in Jinchuan deposit are composed of Class I ores, which indicates that there is a strong melting separation in the deep magma chamber, and the magma is constantly replenished. Although the ore body of Luoshuixia deposit is small, it is mainly Class I ore, which is the result of the deep magma chamber detachment infiltrating into the high-sulfur liquid phase formed by the high-level magma chamber (pulp chamber). This possibility can only be provided by large-scale magmatism. It is speculated that this large-scale magmatism may be the manifestation of the same event as that indicated by Jinchuan.