1. Source of the task
The Malkansu Manganese Ore Belt is located in the western section of Kungai Mountain in the west of West Kunlun, and its administrative division is under the jurisdiction of Aktao County of Kyzyl-Su Kirgiz Autonomous Prefecture of Xinjiang Uygur Autonomous Region, which is an east-west manganese ore belt with a length of nearly 100 km. In 2016, a national-level consolidation exploration area for the national prospecting breakthrough strategic action was established in the region - the manganese ore consolidation exploration area in the Markansu area of West Kunlun, Xinjiang, and the main type of deposit is sedimentary manganese ore. A number of large and medium-sized manganese deposits (Figure 1) and a number of manganese ore prospecting clues have been discovered in the area, such as Ortokanesh, Muhu and Malkantu, among which the Ortokanesh manganese ore has entered the development stage. There is a large number of fourth series cover areas in the middle of the Malkansu manganese ore belt, the manganese-bearing rock system is covered by the fourth series, and the extension of the fourth series coverage area and the manganese ore body outside the known manganese deposit is not known. Therefore, geological survey units mainly based on the Xi'an Geological Survey Center of the China Geological Survey, the Second Geological Brigade of the Xinjiang Bureau of Geology and Mineral Resources, and the Northwest Geological Exploration Institute of the General Administration of Metallurgy and Geology of China have carried out a large number of surveys and explorations in the Malkansu Manganese Ore Belt, with the national public welfare survey as the mainstay, leading the Xinjiang Geological Exploration Fund and enterprises to conduct manganese ore surveys, exploration and development.
Figure 1 A brief map of the geology and mineral resources of the area around West Kunlun Malcansu
Second, the idea of prospecting is determined
In recent years, the West Kunlun Malkansu area has made a major breakthrough in the prospecting of high-quality manganese ore, and newly discovered manganese carbonate deposits such as Ortokanesh, Muhu and Malkan soil, with stable strata and large thickness, are the richest manganese carbonate deposits in northern China. By the end of 2018, the shallow manganese-rich ore resources of 300m have reached more than 5,000 ×104t, with an average grade of more than 30%; the manganese-bearing rock system extends from east to west to Tajikistan, with great prospecting potential in the periphery and depth, and is expected to become the most important 100-million-ton high-quality manganese ore resource exploration and development base in the Silk Road Economic Belt.
The prospecting and exploration of manganese ore in the Malkansu manganese ore belt is also a typical example of the theoretical application of "prospecting for ore", especially in the western extension section of the Muhu-Malkan soil manganese mining area in the eastern part of the Malkansu manganese ore belt and the extension of the deep ore body, and a good prospecting effect has been achieved. From 2016 to 2019, the Xi'an Geological Survey Center of the China Geological Survey and the Second Geological Brigade of the Xinjiang Bureau of Geology and Mineral Resources carried out a large number of investigations in the area for the surface ore bodies that have been discovered, using the theory of "prospecting for minerals" in their periphery and depth. In particular, the Xi'an Geological Survey Center of the China Geological Survey systematically analyzed the mineralization characteristics, ore control factors and prospecting potential of manganese ore through comprehensive geophysical profile tests on the basis of the sedimentary environment research of the manganese-bearing rock system of the Malkansu manganese ore and the structural analysis of the mine area. In the fourth series coverage area of the Muhu-Malkan soil manganese ore mine, the comprehensive geophysical profile test was carried out, and the hidden ore body was investigated by innovative use of well-ground excitation measurement, and the subsequent drilling work proved that the manganese ore body continued to extend to the west, expanding the prospecting space of the manganese ore belt.
From 2017 to 2018, 3 of the 5 verified boreholes constructed in the western section of the Muhu manganese mine and the fourth series coverage area on the north side were seen. Among them: 5 layers of hidden manganese ore bodies were found in the 3 lines, with a cumulative apparent thickness (i.e., false thickness, the same below) of 8.92 m and a manganese grade of 9.42% to 22.11%; the 18 lines found 2 layers of cryptohed manganese ore bodies, with a cumulative apparent thickness of 2.69 m, a manganese grade of 22.77% to 25.44%, and the total length of the main ore body extension exceeded 3 km. Drillographic measurements of wells implemented in the borehole of the western section of the Muhu manganese ore in 2019 show that the manganese ore body continues to extend in a south-westerly direction, pointing the way for the next step of prospecting and exploration in the region. Third, the choice of technical methods
The manganese minerals in the Malkansu area are located in the Malkansu Fault Basin, and the ore-bearing strata are in the thin layered limestone sandwich of the upper Carboniferous Karaat Formation, which is closely related to the sedimentary environment of the land canopy facies and the edge facies of the basin. The main body is a low-energy zone, rare in organisms, and the rocks are darkly hued. Most of the particles are fine-grained and mud-grained calcite, and there are fewer land-based debris. According to the output characteristics of the manganese ore body of the Malkansu manganese ore belt and the genesis characteristics of the deposit, the selection of the prospecting method mainly considers the following factors.
First, based on the typical deposit research and the special geological survey of 1:50,000 minerals, the sequence and sedimentary facies of the manganese-bearing rock system were preliminarily determined, the sedimentary environment was analyzed, and the marker layer system of the manganese-containing rock system was established. The manganese minerals in the Malkansu area are located in the Malkansu Fault Basin, and the ore-bearing strata are in the thin layered limestone sandwich of the upper Carboniferous Karaat Formation, the thickness of the manganese-bearing rock system is large, the manganese-rich ore-bearing layer is stable, and the length of the territory is about 100 km from east to west, and it has extended to the territory of Tajikistan to the west. The fold structure of the area has developed, and manganese deposits such as Ortokanesh, Malkantu and Muhu have been discovered, as well as manganese ore sites such as Susarbulak, Botoyan, Botuoyannan and Tokuzibulak. The limestones of the manganese-bearing ore rocks in the Ortokanesh and Muhu manganese ore areas are closely related to the sedimentary environment of the land greenhouse facies and the marginal facies of the basins. The main body is a low-energy zone, rare in organisms, and the rocks are darkly hued. Most of the particles are fine-grained and mud-grained calcite, and there are fewer land-based debris. Deep water, less sunlight, weak hydrodynamic energy, lack of nutrients, high salinity, low temperature, etc., are not suitable for biological reproduction.
Second, in view of the characteristics of the regional manganese-bearing rock system covered by the fourth series, the comprehensive prospecting method test of manganese mineral exploration was carried out in the Malkansu manganese ore belt, and the geophysical anomalies of different lithology and geological units of Malkansu were preliminarily summarized. The abnormal polarization rate of the well-geodiarrection measurement circle can be effectively speculated about the extension of the hidden ore body, and the excitation method can effectively reflect the shallow stratigraphic boundary, which has obvious effects on the division of the Carboniferous manganese-containing rock system, and the distribution characteristics of the geological body within 500m of the buried depth can be indicated through the difference in geomagnetic depth resistance, and the local gravity anomaly can be used to roughly determine the range of the hidden manganese ore body, which provides a geophysical basis for understanding the deep fold morphology, the distribution of the manganese-containing rock system, the search for hidden ore bodies and the deployment of mineral exploration.
The third is the necessary drilling verification in the hidden area. Drilling verification is a necessary means of prospecting for hidden ore bodies, and on the basis of the previous analysis of the sedimentary environment of the manganese-bearing rocks of the Malkansu Manganese Ore Belt, the favorable areas of prospecting are delineated through comprehensive geophysical profile analysis. Through the comprehensive optimization evaluation of the prospecting target area, the hidden manganese-rich ore body was selected for deep drilling verification in the westward extension of the Muhu manganese ore, and the hidden manganese-rich ore body was found.
The fourth is to expand the regional manganese ore prospecting space, on the basis of remote sensing interpretation and mineral resource potential investigation of the Malkansu manganese ore belt, the prospecting target area is selected, and the special survey of manganese ore is selected to carry out manganese ore prospecting in the favorable area of mineralization, and the regional manganese ore prospecting space is expanded.
Fourth, the process of exploration and discovery
(1) The exploration process of mineral deposits
Since 2008, Xinjiang Baiyuanfeng Mining Co., Ltd. has carried out detailed investigation of the manganese deposit in Ortokanesh in the western part of the exploration area, circled a manganese ore belt with a length greater than 3km in the mining area, controlled 2 of the ore bodies, estimated that the manganese ore resources within 400m of the inclined depth reached 270×104t, and predicted the prospect resources to reach 3500 ×104t, and the manganese grade was between 30% and 40%, which was a large manganese-rich deposit.
From 2013 to 2015, the Northwest Geological Exploration Institute of the General Administration of Metallurgy and Geology of China carried out a general investigation of manganese ore in the first and second districts of Ortokanesh.
From 2015 to 2016, the Second Geological Brigade of the Xinjiang Bureau of Geology and Mineral Resources used the two rights of the autonomous region to investigate and evaluate the manganese ore in the Muhu Belt in the exploration area, delineated 18 manganese ore bodies in 5 ore belts, predicted it to be a large manganese-rich deposit, and found 3 new manganese mineralization clues in the area, which preliminarily confirmed that the manganese ore in the region was produced in the Shangcharinous sand limestone, which was a marine sedimentary manganese-rich deposit, pointing out that the length of the manganese ore belt in the region was greater than 100 km, and the prospecting potential was huge.
From 2015 to 2017, the Zhongnan Geological Exploration Institute of the General Administration of Metallurgy and Geology of China carried out the project of "Prospect Investigation and Evaluation of Manganese Ore Resources in the Malkansu Area of Ucha County-Aktao County, Xinjiang" in the Markansu area of West Kunlun, and analyzed the mineralization conditions and prospecting potential of manganese ore in the area.
From 2016 to 2018, the China Geological Survey's Xi'an Geological Survey Center undertook the china geological survey project "West Kunlun Iron Lead and Zinc Resource Base Survey and Exploration Demonstration" secondary project and its subordinate sub-project "Xinjiang Kenxiville-Atoinak 1:50,000 Manganese Ore Special Mineral Geological Survey", which investigated the characteristics of manganese-bearing rock systems in the Malkansu area and their extension to the east, and found that there was a certain extension of manganese-containing construction to the east. Through the implementation of the project, greater breakthroughs have been made in prospecting in the hidden area of the Malkansu Manganese Belt and in the Permian middle of the belt.
(2) Prospecting thinking and understanding
Malkansu manganese ore belt manganese ore prospecting work from the initial manganese ore prospecting clues to large-scale manganese ore resource base, its prospecting process follows the practice - understanding - practice - re-understanding process, in different stages of prospecting and exploration, continuous comprehensive analysis of the previous prospecting exploration data, the formation of a guide to the prospecting theory, guidance of the prospecting and exploration work. In the early stage of prospecting, only a small number of manganese mineralization clues were found on the surface, and due to the influence of topographic conditions and fourth series coverage, the extension state of the manganese ore body in the mining area was not controlled enough, which affected the evaluation of manganese ore reserves. In the middle period, through the understanding of the characteristics of manganese-bearing rock systems and the structure of the manganese ore area, it was initially believed that the manganese ore area was a dorsal structure, the Ortokannes manganese ore was mainly located in the north wing of the anticline, and the ore body tilted steeply to the north, and the subsequent drilling verification showed that the understanding of the ore body production and extension law in the mining area had a good guiding effect on the prospecting; in the later stage, in the process of prospecting and exploration, on the basis of the previous exploration work, comprehensive analysis of the existing data continued to conduct detailed analysis of the structure, deposit sedimentary environment and sedimentary facies of the ore area. Comprehensive geophysical analysis was used to investigate the extension of the hidden ore bodies of the east and west extensions of the Ortokanesh manganese ore, the Muhu manganese ore and the Malkan soil manganese ore, and achieved good prospecting results.
(3) Application of technical methods and their effects
According to the genesis characteristics, sedimentary facies and sedimentary environment characteristics of the manganese ore deposits in the Malkansu manganese ore belt and the characteristics of a large number of manganese-bearing rock systems in the middle of the manganese ore belt being covered by the fourth series, a series of exploration and research technology methods have been adopted in the prospecting exploration, and good prospecting results have also been achieved.
First, the sedimentary environment analysis of manganese-bearing rock systems was carried out in the Malkansu manganese ore belt. Preliminary research suggests that the fracture troughs under the Tensile System of the Late Carboniferous of West Kunlun Malkansu controlled the evolution of sedimentary basins, and the sequence of biodestic limestone, feldsquartz sandstone, and carbonaceous fine crystal limestone from bottom to top reflected the sequence of sea infestation sedimentation from shallow sea to semi-deep sea and from east to west. The source of manganese minerals may be related to the lower carboniferous basalt, rhodochrosite is formed in a weak alkaline, reducing environment rich in carbon dioxide, and belongs to the "endogenous and exogenous" hot water sedimentary manganese ore, and the carbon quality may reflect its certain control over the valence of manganese ions.
Second, special research on comprehensive geophysical exploration in the hidden area was carried out in the fourth series coverage area of the Malkansu manganese ore belt. The technical methods used and their prospecting effects include: the combination methods of geomagnetic bathymetry, excitation, gravity and geophysical exploration in wells can effectively guide the blinding work of manganese ore exploration, and the abnormal polarization rate of the well-ground excitation measurement circle can effectively infer the extension of the hidden ore body.
Third, drilling verification work was carried out on the hidden ore body in the covered area of the manganese ore belt, and the drilling project implemented in the hidden area of the west side of the Muhu mining area in the eastern section of the Malkansu manganese ore belt on the basis of the previous comprehensive research work found manganese ore body, which confirmed that the manganese-rich ore layer had a certain extension to the west, and the Muhu mining area still had great potential for prospecting to the west. This discovery has driven the further discovery of thick ore bodies in the deep part of the Xinjiang Fund Project, further stimulated commercial exploration, and the resources of the Malkansu manganese ore belt have reached more than 5,000 ×104t.
Fourth, through the special geological survey of 1:50,000 manganese ore, a new Permian manganese-bearing strata was discovered in the Malkansu manganese ore belt. The Botoyannan Manganese Ore Site is located about 1 km south of the Botoyan Manganese Ore Site in the Malkansu Manganese Ore Belt and about 8 km east of the Muhu Manganese Mine, which is a newly discovered manganese ore site in 2018. The ore points are deposited in the altered basalt and Dali rocks of the Kungai Yitaoshan Formation in the Middle Permian, and consist of a ferromanganese mineralization belt and a manganese ore belt. The bandwidth of iron manganese mineralization is 0.5~6.0m, extended by about 600m, the rapid analysis of manganese grade 4%~30%, iron grade 15%~40%, ore minerals are mainly manganese oxide, hematite; manganese mineralization belt is located in the north side of the iron manganese mineralization belt 60~100m, endowed in the Dali rock of the Kungaiy set, the surface of the dew width is 0.5~3.0m, banded, layer-like intermittent extension of nearly 1km, rapid analysis of manganese ore grade of 10% to 30%, the main ore mineral is manganese oxide. Preliminary analysis suggests that manganese mineralization may be the cause of hot water deposition, and ferromanganese mineralization may be the cause of hot water deposition-hydrothermal transformation.
Fifth, the basic situation of mineral deposits
The Malkansu manganese deposit is located 80 km northwest of Muji Township, Aktau County, Kyzyl-Su Kirgiz Autonomous Prefecture, Xinjiang Uygur Autonomous Region, with an area of about 1441 km2. Traffic conditions are poor, the road is located in the west Kunlun Mountains high altitude deep cutting area, landslides, mudslides occur from time to time, has a greater impact on traffic. There are no fixed residents in the area, only seasonal nomadic people, and Muji Township is the closest settlement to the mining area, with animal husbandry, mining and other individual service industries. The mining industry involves lead and zinc ore, manganese ore, gold ore, iron ore and so on. The perennial snow melting provides sufficient water for the rivers, the water quality is good, and the living and production water in the mining area is solved, and other materials need to be transported from Kashgar City by car. At present, the alternating current power of the Bulunkou Hydropower Station only reaches Muji Township, and the power in the mining area in the area mainly relies on high-power diesel generators.
The tectonics of the Malkansu Manganese Ore Belt are located at the junction of the West Kunlun Orogenic Belt and the Tarim Land Mass, and the manganese-bearing rock system is distributed along the Post-Cleavage Basin of the Malkansu Late Paleozoic Arc of the West Kunlun Kunbei Tectonic Belt, and the manganese carbonate deposits such as ore ore such as ore large manganese ore in Ortokanes, Large Manganese Ore in Muhu, and Medium Manganese Ore in Malkan soil have been discovered. The average manganese grade of Ortokanes manganese ore is more than 30%, and the average manganese grade of Malkan soil manganese ore and Muhu manganese ore is about 28%, all of which are high-quality manganese-rich ore. The deposit is marine sedimentary rhodochrosite, the deposit has the characteristics of large thickness, along the trend, tending to extend and stable, etc., the length of the ore body exposed in the Ortokanesh manganese ore area is nearly 8km, and the length of the manganese ore in Muhu and Malkansu is more than 5km, and according to the drilling data, the local ore layer has a tendency to thicken to the depth. The mineral composition of the ore bodies in the Ore deposits in the Malkansu Manganese Ore Belt is basically the same, and the metal minerals are mainly rhodochrosite after the identification of rock ore and the spectroscopy analysis of electronic probes, see a small amount of soft manganese ore, lignite, sulfur manganese ore, silicon manganese ore, pyrite, and occasionally brassite; non-metallic minerals are mainly quartz and calcite.
6. Concluding remarks
The discovery of the large manganese-rich ore belt in West Kunlun Malkansu is an important discovery of manganese-rich ore in northern China, which is of great significance for the search for manganese ore resources in the Carboniferous and Permian systems of the Ring Tarim Basin. (1) Relying on scientific and technological innovation is the key to leading the breakthrough of the West Kunlun Malkansu manganese ore. Strengthen the research of the geological background data of the former region and the exploration data of typical ore deposits, focus on the key geological issues affecting the evaluation of manganese ore resources, realize the in-depth integration of production, education and research, and carry out resource potential evaluation with innovative metallogenic prediction theory, which has played a major role in leading and promoting the breakthrough of manganese ore prospecting in West Kunlun Malkansu Manganese Ore. (2) Innovative mechanism of prospecting breakthroughs, and the linkage of national public welfare projects, geological exploration funds and social funds are the main factors to achieve breakthroughs in manganese ore prospecting. According to the positioning and demand of different funds, so that the public welfare work leads effectively, the commercial exploration follow-up is favorable, the funds are organically connected, the new mechanism of geological exploration in the new era is innovated, and the enthusiasm of all parties can be mobilized, which can greatly accelerate the breakthrough process of mineral prospecting. (3) Comprehensively utilize a variety of high-tech methods to summarize the combination of effective prospecting technology and methods. Actively carry out remote sensing interpretation of multi-source data, comprehensive geophysical exploration method test and effectiveness summary, applied to mineral exploration work, and play an important role in mineral prospecting and target selection in the coverage area.
The next step of work is recommended in several main ways:
(1) It is necessary to further strengthen the study of the enrichment law of Malkansu manganese ore and the formation mechanism of manganese-rich ore, summarize the law of mineralization, and guide the prospecting and exploration of manganese ore in the Malkansu area.
(2) Continue to conduct in-depth investigation and research on the tectonic characteristics of the Malkansu manganese belt. The Malkansu manganese ore belt is affected by the thrusting structure from south to north, the manganese-containing rock system is strongly deformed, and the formation changes frequently along the trend, which requires continuous investigation and research.
(3) Increase the ore prospecting work in the known deep ore deposits of the Malkansu manganese belt and the hidden area in the middle of the ore belt, at present, the Ortokannes, Muhu and Malkan soil manganese ore only controls the resources of 300m ore, and it is necessary to explore and control the resources in the deep part of the deposit.
In addition, a large number of manganese-bearing rock systems in the middle of the manganese ore belt are covered by the fourth series, and it is urgent to investigate the deposit of hidden ore bodies in the coverage area and evaluate the resource potential.
This article is selected from "Successful Cases of Prospecting Thinking: A Collection of Experience in the Discovery of Large-Scale And Super-large Deposits in China in Recent Years"