Evaluation of main metallogenic prospect areas

(1) Metallogenic prospect of Zuoqi gold-copper-tungsten-bismuth-iron polymetallic deposit in Su Nite.

This area is located in Zuo Qi, Su Nite in the south-central part of the work area, and the Bayan Windur mining area, the key work area of this study, is in this area. The geotectonic structure belongs to Paleozoic orogenic belt in central Inner Mongolia, bordering the accretion zone on the northern edge of North China plate in the south and the South Mongolia microplate on the southern edge of Siberia plate in the north. It is located in the south-central part of the Ailigengmiao-Xilinhot intermediate block, and the Erenhot-Hegenshan deep fault passes through its north side. Tectonic and magmatic activities are very complex and intense. The strata of Lower Proterozoic, Upper Paleozoic and Dashizhai Formation and Zhesi Formation of Lower Permian exposed in the area, as well as three large NE-NNE ductile shear zones and Jiaoqier large nappe structure in the south are closely related to gold mineralization in the area.

The structure in this area is dominated by faults, followed by folds. Folds are mainly east-west fold belts and northeast anticlinorium and syncline. The fault structure is mainly the northeast Erenhot-Hegenshan deep fault and its secondary fault structure. At present, the gold deposits (spots) found in this area occur along three large ductile shear zones and nappe structures in a "north-south direction and northeast direction". The Bayanwendol gold deposit submitted this time is located in the northeast Bayanwendol-Barensala ductile shear zone. Regional magmatism is frequent and intense. Early Paleozoic ophiolite, early Variscan, late Variscan-Indosinian, early Yanshan and late Yanshan magmatic rocks are exposed, which have obvious multi-stage and multi-cycle characteristics. The types of magmatic rocks are complex and diverse, and the products are ultrabasic rocks, basic rocks, intermediate-acidic plutonic and hypabyssal intrusive rocks and volcanic rocks, which have a complex geological evolution history. Magmatic rocks are controlled by NE, NNE and EW structures and are distributed in an arc shape. The occurrence of rock mass is bedrock, rock cover and rock plants.

Figure 5-9 Prospect of Gold Mineralization in Erenhot-Dongwuqi Area, Inner Mongolia

Fig. 5- 10 prospect map of copper mineralization in Erenhot-Dongwuqi area, Inner Mongolia

During the Lvliang Movement of about 654.38+0.8 billion years, this area may be a part of the unified ancient North China continent; From Mesoproterozoic to Early Paleozoic, the whole central Inner Mongolia was in a extensional environment. This ancient continent may have undergone a large-scale depression or cracking process, forming a sea basin, rift valley or intercontinental small ocean basin, but the distance between landmasses is not large, and the oceanic crust is not fully developed, and there may be many small landmasses left. From the end of early Paleozoic to the beginning of late Paleozoic, due to plate subduction (from the north of SN), they converged and merged (proliferated) to form a unified continental block; In the late Paleozoic, this area was mainly located in the sedimentary environment of continental margin and epicontinental sea, with the development of andesite-dominated aulacogen and two large-scale eruption activities, and the gold element in the deep crust migrated upward with magmatic activities. From the end of Late Paleozoic to the beginning of Mesozoic, there was a strong intracontinental orogeny in this area, and the Triassic sedimentary formation in the whole area was missing, and it suffered from strong compression in the north-south direction, resulting in strong folding deformation of rock strata, development of nappe structures and ductile shear zones, remelting of crustal materials and abnormal intrusion of magma, which greatly changed the composition of crustal rocks. At this time, the gold element in the stratum was activated and enriched, and gold ore bodies were formed in some areas. Since the late Mesozoic, this area has been influenced by the tectonic activities in the coastal Pacific Ocean, forming a NNE structural belt, and the coexistence of NNE uplift and fault basin is an important structural feature of this area at this time. The Cenozoic is in the late stage of orogeny, and the whole area rises to form a plateau. In a word, the long-term complex tectonic-magmatic activities provide favorable geological conditions for gold and copper polymetallic mineralization in this area.

Vein rocks are developed in this area, and the time-dependent veins are often banded. There are only two natural gold-sand anomalies in this area, one of which has been found (Bayan Wendur gold mine). In addition, in the two copper polymetallic anomalies in the northwest1∶ 200,000, the copper-bismuth polymetallic mineralization point in Wulanhada and the copper-bismuth mineralization point in Wuhe Erchu Road were also found for the first time. Among them, there are many aeromagnetic anomalies, which are widely distributed and strong. The remote sensing interpretation of this area is a dense area of linear and annular structures, and gold mineralization points often develop at the intersection of linear structures or the intersection of linear structures and annular structures. Bayan Wendur and Bayan Baolidao gold deposits have been discovered in this area, which are located at the intersection of linear structure and ring structure. The main types of gold mineralization in this area are chronological vein type and altered rock type gold deposits occurring in ductile shear zone, which are controlled by ductile shear zone and closely related to late Variscan and Indosinian magmatism. Gold mineralization points with further work value have also been discovered in Huduge and Aoqige Aobao in the south of Zuo Qi, Su Nite, and bismuth-copper-gold polymetallic mineralization points with further work value have been newly discovered in Sha 'ertala-Wulanhada-Wuhe Erchulu area. At the same time, there are many mineralization points such as copper, iron, molybdenum and tungsten in this area.

Through the comprehensive analysis of the characteristics of gold deposits in this area, it is considered that gold mineralization in Zuo Qi area of Su Nite is closely related to shear zone, and the following problems should be paid attention to in prospecting in this area:

(1) First of all, it is necessary to strengthen the study of regional secondary shear zone, which is the ore-controlling structure of gold mining area, and the prospecting in this area should focus on the ductile shear zone in the area.

(2) Secondly, because the Cenozoic is widely distributed in this area and the overburden is thicker than that in the west of China, the position of the main shear zone should be determined in a single zone first. Only by finding the location of the main shear zone can we follow the corresponding relationship between fractures and mineralization in the shear zone and further search for shallow time-related vein-type mineralized bodies and deep altered rock-type mineralized bodies. At the same time, we should also pay attention to the study of metallogenic laws such as group zoning, equidistant, symmetry, oblique and structural complexity of shear zone mineralization distribution.

(3) We should also pay attention to the change law of mineralization types of gold deposits (spots) in the three metallogenic belts in the region, that is, from north to south, the mineralization types range from the time-dependent pulse type (Bayan Wendur gold mine) to the time-dependent pulse altered rock type (Bayan Baolidao gold mine) and then to the altered rock type (365 gold mine). At the same time, the granularity and coarseness of the Ahsaha granite, which is roughly the same as the gold mineralization, indicate that the whole region is deeply eroded.

At the same time, it should be noted that the polymetallic mineralization of bismuth and copper in this area is developed in the time pulse, and the occurrence of the time pulse is near the contact zone of magmatic rocks or outside the stratum. Therefore, it is speculated that the polymetallic mineralization of bismuth and copper is closely related to the multi-stage magmatic intrusion in this area. Although the surface time-dependent pulse mineralization has been discovered at present, there is the possibility of polymetallic mineralization of copper-bismuth porphyry in the deep, which was not noticed by predecessors when they worked in this area.

(II) Wulan Tolgoi-Chagan Chulutu Cu-Pb-Zn-Ag-Au polymetallic metallogenic prospect area

The scenic spot is located in Wulan Tolgoi-Chagan Chulutu area in the northeast of Dongwuzhumuqin Banner. The strata exposed in the exploration area are Paleozoic Ordovician Tongshan Formation and Duobaoshan Formation, Devonian Mishuhe Formation and Anger Yinwula Formation, Carboniferous Baoligemiao Formation and Mesozoic Jurassic Bulagenhada Formation. Among them, the Devonian Anger Yinwula Formation and Carboniferous Baoligemiao Formation are closely related to mineralization in the region. Magmatic rocks exposed in distant scenic spots are mainly distributed in two stages: Variscan and Yanshan. There is biotite granite in the middle of Variscan, which is called the very old Zhuer rock mass. It appears in the form of bedrock, starting from the south of Mahwendur in the west and reaching Baolige Sumu in the north. The bedrock invaded the Carboniferous strata. Secondly, in the late Variscan period, diorite, quartz diorite, diorite porphyrite, diabase porphyrite, potash granite and syenite were distributed in this area, all of which were produced in the form of smaller rock plants and dikes. Most of these rocks and dikes extend to the northeast. Generally consistent with the direction of the tectonic line. The Yanshanian intrusive rocks in this area are mainly moderately acidic, including biotite granite, granite porphyry, syenite monzoporphyry and diorite porphyry, which are exposed in Baolige, Jilin, Tolgoi, Erdene and Glastre in the form of small rocks and dikes. In addition, the intermediate-acid and acidic rocks in the late Yanshan period invaded both sides of Dongwuqi Uplift, that is, the two wings at the northeast end of anticlinorium in Tolgoi, Erdene. These two intrusive rocks are closely related to mineralization in this area.

The geological structure in this area is relatively developed, with Dongwuqi compound anticline structural belt as the main body, running through the whole area and extending in northeast direction. The compound anticline structural belt starts from Maihe Wendur and Jirgalang Aobao in the west and reaches the Tolgoi area in Erdene in the northeast. It is about 80 kilometers long and 20 ~ 30 kilometers wide. Anticlinorium consists of Devonian Mishuhe Formation, Anger Inula Formation and Carboniferous Baoligemiao Formation. The northwest wing stratum is relatively complete, and the southeast wing stratum is incomplete. Axial faults developed in the middle of anticlinorium and were swallowed up by intrusive rocks in Variscan and Yanshan periods. Anticlinorium also has the characteristics of rising in the northeast and falling in the southwest.

This area should be a small block in the northern part of South Mongolia Ocean in the early Early Paleozoic and before. In the late Early Paleozoic and the middle and late Paleozoic, it experienced a continuous over-arc basin-type volcano-sedimentation, accompanied by volcanic-intrusive rock activities, and the development scale of its over-arc basin was much larger than that of Zuo Qi, Su Nite in the west. There were also sporadic small-scale alkaline magmatic activities in the early Mesozoic; In the late Mesozoic, due to the comprehensive action of various regional stresses, a large-scale fault basin developed in this area, and the continental volcanic-sedimentary process was very strong, accompanied by a considerable scale of intermediate-acid magmatic intrusion. This area is one of the most concentrated metallogenic areas in the study area, and the minerals are mainly copper, silver and lead polymetallic minerals. There are Wulan Huduge copper deposit, Jilin Baolige silver polymetallic deposit, Wulan Tolgoi copper-silver-lead-zinc deposit, Erdene Tolgoi copper deposit, Mahu Wendur copper-lead-zinc polymetallic deposit, Wendur Aobao polymetallic deposit, as well as Talbagtu, Zhalan Tolgoi, Aobao Tehaolai and Shananan polymetallic deposits. There are Dasaituo and Alhada, Chaobuleng lead-zinc mine, Chagan Aobao lead-zinc mine and Morton (medium-sized? ) Lead-zinc deposit. In addition, there are many heavy sand anomalies in lead, ilmenite and cinnabar, and copper, lead and zinc anomalies in a large area. Genetic types of deposits in this area According to this survey, the polymetallic minerals in this area belong to subvolcanic hydrothermal type (subvolcanic porphyry type) in the east and subvolcanic porphyry type in the west. Mineralization in the east is closely related to Mesozoic volcanic activity. The western segment is related to the intrusion of granite and porphyry in Variscan period. The ore-controlling characteristics of the structures in this area are that the secondary low-order structures in the northeast, northwest and near east-west directions are important ore-hosting and storage structures.

On the remote sensing image, there are dense linear and annular structures, and the linear structures are mainly ne and NW. Ring structure can be divided into simple ring, compound ring, cut ring, sub-mother ring and so on. From the analysis of genetic types, it can be divided into intrusive rock mass, concealed rock mass, volcanic activity mechanism and annular fault structure. The scale of these ring structures is generally small and medium-sized ring structures with a diameter of 2 ~ 3 km, with * * * 1 1. It is characterized by overall dispersion and local concentration. The linear structure in this area is closely related to minerals. Due to the multi-period, inheritance and transformation of geological tectonic movement, secondary structures develop in a network in favorable metallogenic areas, and the matching relationship of local structures is not easy to understand. Judging from the overall pattern of the whole area, the NE-trending Mahwendur-Erdene-Tolgoi linear fault structural belt is the most important rock-controlling and ore-controlling structure in this area, which may belong to a deep and large through fault. Several mines in this area, such as Mahewendur, Wulan Tolgoi and Erdene Tolgoi, are distributed along one side of this structural belt. Secondly, the secondary medium-scale linear fault structure derived from it is an important ore-controlling structure. These low-order, small-scale faults and fracture systems, which are contemporaneous with NE-trending and NW-trending faults and folds, constitute the important ore-bearing structures of the metallogenic profile in this area. Such as Wulan Tolgoi copper mine and Erdene Tolgoi copper mine, the distribution of each ore belt is controlled by low-order fault system.

This field investigation found that most of the deposits in this area have the value of further prospecting. Combined with remote sensing interpretation, this paper preliminarily summarizes several links that should be paid attention to in prospecting in distant scenic spots:

(1) The favorable position for remote sensing interpretation of linear structure has a certain scale of linear structure development, which is located at the intersection of NE and NW linear structures, while the secondary linear structures near EW or NNE and SE pass through, accompanied by small and medium-sized ring structures.

(2) Remote sensing images show mottled, mottled, patchy and patchy shading color features, or sections with fading shading information of light tones.

(3) There are known deposits and occurrences, favorable areas with obvious signs of metallogenic types, regional geochemical anomalies related to metallogenic elements and abnormal areas related to prospecting targets.

(4) There is a section of Devonian Angyinwula Formation or Carboniferous Baolige ore-bearing strata, accompanied by the exposure of Variscan and Yanshanian magmatic rocks, or the distribution of hydrothermal active veins.

(5) Field investigation shows that there are certain prospecting indicators, mineralized zones and zones with superior mineralized conditions on the surface.

(3) Chagan Aobaomiao-Honggeer copper-gold polymetallic metallogenic prospect area

The scenic spot is located in the Chagan Aobao Temple-Honggeer area on the border between China and Mongolia in the northwest of the study area. The tectonic position of this area is located in the island arc area on the north side of the late Paleozoic plate suture zone in central Inner Mongolia. Located at the western end of the Honggeer-Jirgalangtu metallogenic belt. In Mesozoic, due to the oblique subduction of the Pacific plate NNW, the tectonic magma activity was intense, and a series of NE-Nee tectonic magma uplift zones and volcanic rift zones were formed, which constituted the unique tectonic environment in this area. The regional strata are Paleozoic Ordovician, Devonian and Carboniferous-Permian, and the lithology is metamorphic sandstone, slate and crystalline limestone. Mesozoic Jurassic, lithology is acidic volcanic rocks, crystal chips and glass chips tuff. The regional structure is complex, and the fault structures are large NE-trending ultra-lithospheric faults in Erenhot-Hegenshan, Chagan Aobaomiao-Arong Banner and NW-trending deep faults in Abaga Banner. At the end of the Late Paleozoic, a strong folding movement occurred, forming the Wuzhniletu fold structure and the NEE-oriented fault structure, which formed a part of anticlinorium in Erenhot-Dongwuqi. The regional magmatic activity is strong, and the granite complex invaded in different stages has many cycles. There are diorite, granodiorite, early Yanshanian granite and potash granite. It is distributed in the northeast, and the occurrence is bedrock and rock plants, covering an area of 20 square kilometers to hundreds of square kilometers. At the same time, there are many kinds of dikes, which develop from acidic to alkaline. There are mainly granite porphyry veins, felsic porphyry veins, diorite veins and diabase veins.

Before the Early Paleozoic, this area was a land mass of the South Mongolia Ocean, which was invaded since Devonian, and Devonian and Ordovician clastic rocks were deposited, and some places were deep in the sea. In the middle Paleozoic ancient island arc area, volcanic magmatism developed in the middle Paleozoic; At the same time, a large number of intermediate-acid granite magma intrudes, and the lithology is mainly granodiorite and diorite. After the combination of South Mongolia block and North China plate, a small extensional basin developed in this area. There was a small-scale granite intrusion in the south of Yanshan period. Judging from the characteristics of magmatic activity, the distribution of mineralization points and the existing occurrence anomalies, it mainly includes a series of copper and gold points, mineralization points and a large number of heavy sand anomalies. Among them, Honggeer Gold Mine, one of our newly discovered gold mines, is located in the western part of the scenic spot near the border area. The western and northern borders of this area are mostly covered with desert and gravel, with heavy wind and sand all the year round, underdeveloped grassland vegetation, harsh geographical environment and extremely low geological degree and mineral exploration degree. This area extends westward to Mongolia, and there is a famous Chagan Subul porphyry copper polymetallic deposit.

Regional geophysical and geochemical exploration and heavy sand anomalies are concentrated in the early tectonic-magmatic active zone of Chagan Aobaomiao-Arong Banner and the late tectonic-magmatic active zone of Erenhot-Hegenshan Hualixi. The background value of gold in this area is high, with gold as the main mineralization form and other non-ferrous metals associated with gold. There are many heavy placer gold bodies in variscan and Yanshanian granites, and the abnormal scale of heavy placer is large. According to remote sensing interpretation, this area is a densely populated area with linear and annular structures. The intersection of linear structure and ring structure is beneficial to the production of gold ore bodies. Regional minerals include gold, copper, iron, lead and other polymetallic minerals, which are distributed in the Hualixi granite complex or in the contact zone with surrounding rocks. The prospecting prospect of polymetallic deposits in this area is good.

Judging from the only research degree in this area at present, the output of minerals is closely related to magmatic activity. The types of gold deposits are mainly time-pulse type and altered rock type gold deposits occurring in the contact zone of internal and external magmatic rocks, with only a few mineralization points of copper polymetallic deposits. Compared with the Chagan Subul porphyry copper polymetallic deposit in neighboring Mongolia, the geological work level is obviously insufficient. Because the area is a grassland Gobi area with serious coverage, a single geological means is used to find mine disasters in order to make a breakthrough.

(IV) Yihe Wuhua-Jirigalangtu Copper-Silver-Gold Polymetallic Metallogenic Prospective Area

The scenic spot is located in the Yihe Wuhua-Jirigalangtu area on the northwest border of China and Mongolia in Abaga Banner. The structure is located in the north of the late Paleozoic plate suture zone in central Inner Mongolia, belonging to Dongwuqi back-arc basin. Due to the special tectonic background, the tectonic and magmatic activities in the area are strong, and it is one of the most concentrated metallogenic areas in the study area, with copper-gold deposits (spots) as the main ones, followed by silver polymetallic deposits. According to recent exploration, bismuth mineralization has also developed in this area. The main deposits are Barun Suridrich gold deposit, Hogan Tolgoi silver polymetallic deposit, Mologqin copper polymetallic deposit, Azahada copper bismuth iron gold polymetallic deposit and so on. The field investigation shows that all the known deposits (spots) are in the range of1∶ 200,000 geochemical anomalies, and most of them have good metallogenic conditions and obvious mineralization, which are closely related to magmatic rocks in the area. The field route investigation shows that the granite body in Azahada Cu-Bi-Fe-Au polymetallic mining area develops copper mineralization as a whole, and there is the possibility of porphyry Cu-Bi polymetallic ore body in the deep part. At the same time, this area has recently become one of the hot spots in geological exploration of copper polymetallic deposits in Inner Mongolia.

(5) Chagan-Aoyoute Cu-Pb-Zn-Au polymetallic metallogenic prospect area in Suizhong.

The prospect area is located in Chagan-Aoyoute area in Suizhong, northwest of Abaga Banner, and its structural position is the same as that of Yihe Wuhua-Jirigalangtu polymetallic metallogenic prospect area. Indosinian granite is developed in this area, which is distributed in the northern part of the remote scenic spot, followed by late Variscan granite and early Yanshan granite. The formation of endogenetic copper, lead and zinc polymetallic minerals in this area is mainly related to the intrusion of potash granite in the early Yanshan period, which is distributed in the northeast structural belt. There are many anomalies of heavy sand and anomalies of metal contents of gold, tungsten and lead in this area. At present, there are Aoyou ultra-small copper-silver gold mine, Suizhong Chagan copper-lead-zinc polymetallic mine and a series of copper polymetallic anomalies in individual anomalies. Aoyoute Cu-Ag-Au deposit is very representative in this area. There are upper Devonian sandstone and a small amount of tuff exposed in the north of the mining area, and granite invaded in the early Yanshan period. In the late period, dikes developed, mainly in quartz porphyry, and mostly distributed in the northeast. The southern section of Oyute is mainly exposed in the upper Jurassic Quantong-volcanic strata, including rhyolite, rhyolite clastic rock and rhyolite tuff, and a small amount of upper Devonian sandstone is exposed. The main structural line in the area is ne, which controls the distribution of mineralized zones and ore bodies. The deposit belongs to subvolcanic hydrothermal type, and its mineralization is related to early Yanshanian granite or its shallow chronological porphyry dike. Many mineralization points such as copper, lead, zinc, tungsten and gold have been found in this area, all of which have the prospect of finding polymetallic deposits.

(6) Hegenshan-Xiaobaliang Fe-Cr-Cu-Au-Pt metallogenic prospect area

The scenic spot is located in Hegenshan-Xiaobaliang area in the east of the study area and southwest of Dongwuzhumuqin Banner. The prospect area is mainly distributed on both sides of Erenhot-Hegenshan fault. The strata related to metal mineralization are mainly Permian and Carboniferous, which are widely distributed in this area. Magmatic activities are frequent and widely distributed in this area, which are mostly controlled by structures and closely related to various endogenetic metal minerals.

This area is generally consistent with the middle and late Paleozoic block accretion splicing zone. It is the remnant area of the Early Paleozoic-Middle Paleozoic South Mongolia Ocean. Therefore, volcanic sedimentary strata developed in the early Paleozoic or even earlier, and then metamorphic formed the famous Wendur Miao group (northern belt). After the closure of the Middle Paleozoic ocean basin, basic-ultrabasic rocks of different scales were scattered from west to east in this area, which was studied as a typical ophiolite suite by predecessors, among which Genshan ophiolite is one of the famous ophiolite suites in northern China. The west of the metallogenic belt is directly connected with the suture zone in the south of Zuo Qi, Su Nite, and the northeast is adjacent to the arc basin metallogenic belt in the north through a late Paleozoic-Cenozoic extensional basin. From this point of view, its northern part (south of South Mongolia block) has the nature of pre-arc basin.

There are many aeromagnetic anomalies, gold-copper heavy sand and metal content anomalies in the area, as well as small chromium mines, chromium deposits, platinum mineralization points and gold-platinum heavy sand anomalies. Xiaobaliang copper-gold deposit has been discovered in this area. The surrounding rocks of the ore body are andesite and andesite tuff of Gegenaobao Formation of Lower Permian. Late Variscan syenite porphyry is distributed in the north and south sides of the mining area and intrudes into andesite and tuff of Gegen Aobao Formation. It extends nearly east-west and tends to the south, which is related to the formation of copper deposits in this area. The fault is distributed in NEE direction, and syenite porphyry runs through it. At the same time, many copper and gold deposits have been discovered in this area, such as Wunite Ranch, Xiaoshidingshan, Wulagawula and Aershan Baolige copper deposits, indicating that this area has certain prospecting potential.

(VII) Mai Sha-Taligan Aobao Tungsten-Tin-Gold-Lead Polymetallic Metallogenic Prospective Area.

The scenic spot is located in the Mai Sha-Tarrigen Aobao area from the north of Dongwuzhumuqin Banner to the border between China and Mongolia. The tectonic position and evolution are consistent with the prospect of copper-lead-zinc-silver-gold polymetallic mineralization in Wulan Tolgoi-Chagan Chulutu. This area is characterized by the large-scale development of Yanshanian granite, and the previous geological characteristics have basically been completely transformed and disappeared. At present, the known deposits (spots) in the exploration area mainly include Mai Sha tungsten deposit, Ustainwula wolframite deposit, Ustainwula North copper deposit, Birut wolframite deposit, Angyinwula lead deposit, Zhaladong copper deposit, gemes Gehu copper deposit and Aobao copper deposit. Although a large number of deposits (spots) have been found in this area, no large deposits have been found so far because of the relatively low level of geological work. At the same time, there are many anomalies such as tungsten, tin, gold and copper in this area. In addition, Batwa (medium? ) tungsten ore, Nandezr (medium? ) tungsten and molybdenum deposits and many other places. The field route survey shows that most mineralization points in this area have further work value and are one of the key areas for geological prospecting in the future.