Forecast example

(1) Prediction of new metallogenic belt (taking Guangxi as an example) (Ji Kejian et al., 1989)

The hydrothermal deposits in Nanling area are mainly related to Yanshanian magmatism. However, the Yanshanian intermediate-acid magmatic rocks in Guangxi are not developed, and there are only 17 rocks on the granite distribution map of different ages in South China compiled by the Department of Geology of Nanjing University, which is much less than the Yanshanian rocks in neighboring Hunan Province and Guangdong Province. However, most granite bodies in Guangxi are associated with hydrothermal deposits, which account for a large proportion of the total number of rock bodies, exceeding 50%. This ratio is greater than or much greater than that of neighboring provinces such as Hunan and Guangdong. According to the three-source hydrothermal metallogenic model, this is feasible. Because the source beds (tungsten, tin, lead, zinc, etc. The hydrothermal deposits in Nanling area are mainly pre-Devonian clastic rocks, and the upper Paleozoic carbonate rocks are water sources with good permeability and water abundance. Except for the northeast edge and southeast, the Upper Paleozoic with relatively gentle occurrence is widely distributed in most areas of Guangxi. That is to say, in most areas of Guangxi, the water source layer and mineral source are superimposed together. When magma intrudes, it can form three source areas, generate ore-forming hydrothermal solution and form hydrothermal deposits.

Figure 14-6 Schematic Diagram of Longitudinal Geological Profile of Xibulan Ore Belt

(According to Wu Yongle 1987)

1- Middle-Upper Cambrian; 2- Early Yanshanian biotite granite; 3- Ore-bearing quartz vein; 4- Ore-bearing quartz vein zone; 5— Upper boundary line of main industrial ore bodies of each deposit; 6- Lower bound relation of main industrial ore bodies of each deposit; 7 —— The connection of the best parts of the main industrial ore bodies in each deposit.

Figure 14-7 Geological Profile of Shihai Coral Tungsten Tin Vein

(According to Zhu Yanling 198 1)

1— limestone of Donggangling Formation; 2- sandstone and limestone of Yujiang Formation (upper member); 3-sandstone of Yujiang Formation (lower member); 4-sandstone shale of Changling Formation; 5- Lianhuashan Formation sandstone; 6- Normal fault; 7- W-Sn timely vein; 8 pulse group number

The regularity of granite distribution in Guangxi is extremely obvious, and almost all of them occur in or near the axis of anticline. As mentioned earlier, in the process of magma upwelling, if it encounters an aquifer, it loses its ability to rise, so it can only be emplaced at or near the axis of the anticline lacking an aquifer.

Figure 14-8 Geological Profile of Pangushan Tungsten Bismuth Deposit

(According to Xia Hongyuan 199 1)

1-Upper Devonian sandstone splint rock; 2- Sinian-Cambrian phyllite and slate; 3- Yanshanian granite; 4- Unconformity stratum boundary; 5- Fault; 6— Ore vein and serial number

Because water resources and mineral resources coexist in most parts of Guangxi. Therefore, the key to predict hydrothermal deposits is to predict concealed rock masses, some of which are distributed along the anticline axis. Therefore, the anticline belt is a prospective belt of hydrothermal deposits. There are obvious anticline groups in Guangxi: ① Napo-Daxin-Nanning-Guixian-Hexian anticline group, in which Qinjia, Kunlunguan, Liu Na, Guixian, Xishan, Huashan and Guposhan rock bodies are distributed, almost all of which are related to hydrothermal deposits such as tungsten, tin, lead and zinc; ② Hengxian-Mashan-Nandan anticline group belt, distributed in Kunlun Pass, Damingshan, Mola, Dachang and Mangchang rock bodies, all related to hydrothermal deposits; (3) Xiangzhou-Yangshuo-Guanyang anticline group belt, it is known that chestnut-calcium rocks are related to hydrothermal tungsten-tin, lead-zinc deposits. Among the above three anticline-magmatic rock belts, according to the distribution map of concealed granite inferred by Demei Sun according to Bouguer gravity anomaly (Figure 14-9), there are not only the above three magmatic rock belts, but also concealed rock bodies, such as Zhenlongshan (ⅹⅹⅹⅹⅹⅹⅹ). For example, there is skarn in Nanyuan Cave, which is an important sign of heat source, and there is a certain scale of concealed rock mass in the deep. There is also the heavy sand anomaly of Sn, which is located in the overlapping part of three sources and is an ideal hydrothermal metallogenic prospect. ④ The Zhou Lu-Bama-Lingyun-Longlin anticline group belt has not formed tungsten, tin, lead and zinc deposits because of its low working level, which has not been paid attention to. However, according to the three-source hydrothermal metallogenic model, this belt is very similar to other anticline-magmatic belts, and it is an anticline group belt, with Yanshanian granite exposed and obvious hydrothermal mineralization alteration near the rock mass or at the core of the anticline. The difference between this zone and the above three zones is that the strata in the core of this anticline are Devonian and Carboniferous, and the other three zones are mostly Cambrian or Devonian; The scale of intrusive rocks in this area is very small. Although 7 rocks are shown on the geological map of1:2 million, the related hydrothermal deposits have not been determined (figure 14- 10). The core stratum of the anticline in this belt is relatively new, which is a feature of northwest Guangxi, and the core stratum of the anticline in Dachang-Mangchang area is also Devonian. The new strata in the core of the anticline show that the depth of ore source bed in this belt is slightly greater than that in other belts. Therefore, hydrothermal deposits are brought deeper from the surface than other deposits. Because this belt is also a anticline-magmatic belt, there are hydrothermal deposits, mineral sources, water sources and heat sources. Therefore, there is a great possibility of hydrothermal deposits. From the Bouguer gravity anomaly map, Zhou Lu-Lingyun is not only a concealed rock mass, but a complete concealed rock mass zone. The geological and structural conditions in this zone are very similar to those in Dachang-Mangchang, which is in the position of structural variation. Dachang-Mangchang itself is located in the NW-trending fault fold belt, while the east side is located in the NE-trending fault fold belt. Therefore, the rock mass and hydrothermal deposits are obviously controlled by two groups of faults in NW and NE directions. The north side of Zhou Lu-Lingyun belt is dominated by nearly N-S faults and folds, and the south side is dominated by NW-NE faults and folds. Therefore, there are three groups of faults in this zone, north-south, northeast and northwest, which control three groups of dikes in different directions. Granites in the two zones mainly exist in the form of dikes or dike groups. The dikes are similar in scale and the same in lithology, and all occur in and near the axis of anticline. The image characteristics of satellite photo interpretation in Lingyun area are very similar to those in Dachang-Mangchang area. The Devonian granites invaded by Guangxi and their adjacent granites are almost all related to hydrothermal deposits, such as Qinjia, Daming Mountain, Dachang, Mangchang, Kunlunguan, Zhenlongshan, Xishan, Huashan, Guposhan and Limu. The rock mass in Zhou Lu-Lingyun area also intruded into Devonian or Carboniferous, so this belt may be not only a metallogenic prospect of hydrothermal deposits, but also an important nonferrous and precious metal metallogenic belt similar to Dachang-Mangchang (large scale and large number of deposits). However, this zone is located in a relatively declining fault block, and the degree of erosion is weaker than that in Dachang area. If there are hydrothermal deposits, there are fewer ore bodies exposed to the surface than in Dachang area, and the buried depth of ore bodies is relatively large. This may be one of the important reasons why the rock mass in this zone still belongs to non-associated rock mass.

Figure 14-9 Distribution Map of Concealed Granite in Guangxi

(According to Demei Sun, etc. )

1- Yanshanian granite outcrops; 2- Exposed Indosinian granite; 3- Exposed Hercynian granite; 4- Exposed Caledonian granite; 5- Exposed Xuefeng-Bao Si granite; 6- Inferring concealed granite; 7— Bouguer gravity anomaly isoline (mGal)

Figure 14- 10 Distribution Map of Yanshanian Granites in Guangxi

(According to Ji Kejian et al. 1989)

1- associated hydrothermal deposit rock mass; 2— Rock mass without related hydrothermal deposits

(2) Prediction and optimization of metallogenic prospect area (taking northern Liaoning-northern Hebei gold mine as an example)

1. Distribution law of hydrothermal gold deposits

In the northern margin of North China landmass, the distribution of gold deposits is closely related to the three major sources of ore, water and heat. Gold deposits are concentrated in Archean green rock series, accounting for 765,438+0% of the total gold deposits. A considerable number of gold deposits are not directly produced in Archean green rock series, but in nearby rock series. Archean is the source body of gold deposits, so gold deposits are concentrated in or near the source body; Most gold deposits occur near and in rock mass, accounting for 86% of the known deposits. Rock mass is the heat source for the formation of gold deposits, so it can be said that most gold deposits occur in or near the heat source; Almost all gold deposits occur at or near the Mesozoic basin edge or in carbonate-dominated strata, such as Proterozoic. These strata are all permeable and water-bearing strata, and they are all water sources, that is to say, almost all gold mines are distributed near the edge and water sources.

Gold deposits are controlled by ore source, water source and heat source, and non-three-source areas cannot be concentrated areas of gold deposits. Such as Zanhuang, Lvliang and other areas, although there are a large area of Archean outcropping, that is, there are more common ore sources, but there is no heat source, so there is no activation, migration and enrichment of ore sources. It can be seen that it is difficult to judge the metallogenic prospect of gold deposits according to a single provenance, because the formation of gold deposits is not only controlled by a single provenance. There may or may not be gold deposits in areas with single ore source distribution, water source distribution or heat source distribution, depending on the existence and spatial allocation of the three ore sources. For example, magmatic rocks are generally developed in the Yanshan tectonic-magmatic belt from Daxing 'anling to Taihang Mountain, which is distributed in the northeast, but in the northern area dominated by Upper Paleozoic and Mesozoic (there are heat sources and water sources, but the mineral sources are lacking or insufficient). However, there are many gold deposits in the southern Archean (with three sources of ore, water and heat).

Gold deposits are concentrated at the intersection of ore, water and heat source. Only the intersection of the three sources is the hydrothermal generation area, and only the hydrothermal generation area is the hydrothermal deposit formation area. Therefore, gold deposits must be concentrated at the intersection of three ore sources. According to the statistics of three-source conditions of medium-sized gold deposits in five provinces in the northern margin of North China landmass, the deposits occurring at the intersection of three sources account for 8 1.5% (table 14- 1).

Table 14- 1 Statistical Table of Production Conditions of Medium-sized Gold Deposits in Five Provinces on the Northern Margin of North China Block

Tables 14-2 and 14-3 list the relationships between medium-sized and above gold deposits and Archean source rocks, Yanshanian heat sources and Mesoproterozoic water sources in western Liaoning, northern Liaoning and northern Hebei. It can be seen from the table that there are 3 1 medium-sized or above gold deposits in the * * area of northern Liaoning and northern Hebei, most of which are located at the intersection of three sources, and one deposit of Archean ore source body, Yanshanian heat source body and Mesoproterozoic water source body has not been found. This statistical data clearly shows that the output of gold deposits is strictly controlled by the conditions of three sources.

Table 14-2 Relationship between medium and large gold deposits and three ore sources in western Liaoning and northern Liaoning

Table 14-3 Relationship between medium-sized gold deposits and three ore sources in northern Hebei Province

2. Three-source metallogenic model of gold deposits in northern Liaoning-northern Hebei region.

According to the basic geological characteristics of gold deposits in the area and the situation of three sources of ore, water and heat, we have compiled a three-source metallogenic model map suitable for geological prospecting (figure 14- 1 1). According to the number and spatial position of the three provenances, the map is divided into three single source areas (I- 1 is a single heat source area, I-2 is a single ore source area and I-3 is a single water source area). Three types of secondary source areas (Ⅱ-1is the mine source heat source area, Ⅱ-2 is the heat source water source area and Ⅱ-3 is the mine source water source area); Although the ore source, water source and heat source geological bodies of the five types of three source areas are basically the same, they can still be divided into five combination types (Figure14-12): Ⅲ-1The mining area or ore field is dominated by Archaean, and there are subsidence caprocks in Mesoproterozoic (-Mesozoic) and intrusive bodies in or near the caprocks. The relative subsidence area in the caprock of the depression is the water source area, and its vicinity is the coexistence area of mineral source and water source. When the heat source invades, it becomes the intersection of three sources and is easy to mineralize. The representatives of this kind of gold deposits are Jinchangyu, Niuxinshan, Yueerya, Paishanlou, Dongping and Jiapigou adjacent to this area. Gold deposits mainly occur in Archean basement, which are arranged from the contact interface between basement and caprock to the basement far from the interface: Maojiadian, Paishanlou, Huajian, Niuxinshan and Jinchangyu deposits; Secondly, gold deposits also occur in caprocks, such as Baizhangzi in quartzite, Great Wall and Qinghe along carbonate rocks. There are also gold deposits in Yanshanian rocks, such as Niuxinshan deposit in Archean rocks and Yuerya deposit in caprock rocks. It can be seen that this type is one of the important three-source plastid assemblage types of gold deposits, and there are many types, quantities and scales of gold deposits belonging to this type; ⅲ-2 mining area or ore field is dominated by Archean or Proterozoic, with some remnants of Mesozoic basins or Proterozoic strata and intrusions, that is, there are three sources of ore, water and heat in the area, which is a favorable gold mineralization area. The gold deposits belonging to this type are Wulong, Sidaogou and Gaojiadian in eastern Hebei. The middle part of Ⅲ-3 mining area or ore field is Archean, with Mesozoic basin at the edge. There are a certain number of Yanshanian rock masses in the area, and there are many three-source intersection areas in the area, which have good gold mineralization conditions. Dongping-Xiaoyingpan, Jinchanggouliang and Dayingzi ore fields belong to this type. ⅲ-4 mining area or ore field is located in Mesozoic basin, with a small amount of Archean and Yanshanian rocks exposed locally, which has good three-source conditions. The representative of this kind of ore field is Honghuagou-Lianhuashan gold ore field. ⅲ-5 mining area is a Mesozoic basin with Yanshanian dikes and deep crystalline basement, which has the conditions of three sources, and its representative is Hongshilazi Gold Mine in Liaoning Province.

Five types of three-source combination can be divided into two types: combination type ⅲ- 1, where ore source bodies are juxtaposed with water source bodies and heat source bodies are superimposed; The upper part is a basin (Mesozoic, etc.). ) and the lower part is Archean basement, or the upper part is water source and the lower part is mineral source, with superimposed heat sources, such as III-2 to III-5. The difference between them lies in the depth of mineralization and the degree of erosion. From Ⅲ-2 to Ⅲ-5, the mineralization depth changes from deep to shallow or the denudation degree changes from large to small.

3. Three-source prediction of gold deposits in northern Liaoning-northern Hebei region

According to the geological map of1:500,000 in Liaoning and Hebei provinces, we have compiled the three-source metallogenic prediction map of 1: 1 10,000 gold deposits in northern Liaoning and northern Hebei (see the illustration 14- 13). In this picture, Archean is regarded as the ore source, Mesozoic basin (and Paleozoic and Proterozoic strata) as the water source, and Yanshanian magmatic rocks as the heat source. And try to circle a circular three-source prediction area with a diameter of 5 ~ 10 km.

Table 14-4 lists all the three-source prediction areas, and the number in brackets after the prediction area indicates the number of known gold deposits in the prediction area. There are 189 prediction areas in the whole region, including 47 gold prediction areas and 42 non-gold prediction areas. The former accounts for 1/4 and the latter accounts for 3/4. These two prediction areas have prospecting prospects. There are 65,438+006 gold deposits in this area. There are 68 known gold deposits in the three-source prediction area, accounting for 64% of the gold deposits in the whole area, while the area with gold deposits in the three-source prediction area accounts for about 5% of the whole area. It can be seen that gold deposits are concentrated in the three-source prediction area, especially large and medium-sized gold deposits are almost all in the three-source prediction area.

Figure 14- 1 1 Three-source metallogenic model of gold deposits in northern Liaoning and northern Hebei.

1-Mesozoic (one of the water sources); 2- Mesoproterozoic (one of the water sources); 3- Archaean (ore source); 4- Yanshanian granitoids (heat source); 5- Strata or rocks of other times except Mz, pt and AR; 6- fracture; 7- gold mine; 8— Different combination types of mineral source, water source and heat source

Figure 14- 12 Schematic diagram of different types of three-source plastids and gold deposits.

ⅲ- 1- graben water source body (j-pt2-3) in Miocene Archean ore source body; Ⅲ-2-Mesozoic water source body remaining in Archean or Proterozoic ore source body; Ⅲ-3-a large Archean ore source body exposed between Mesozoic basins; There are a few Archean small ore source bodies exposed in Ⅲ-4-Mesozoic basin. Ⅲ-5—Middle Yanshanian dike in Mesozoic basin. Ore source body: Ar- Archaean; Pt 1- Proterozoic; Water source body; PT2-3- Mesoproterozoic; J- Jurassic; Heat source body; -Indosinian granite; -Early Yanshanian granite; -Late Yanshanian rhyolite porphyry. gold mine

In addition, the Chifeng area in Inner Mongolia with similar geological conditions is predicted on the prediction map, and the 16 prediction area is circled. Although they are not named by numbers, they are all three-source prediction areas and also have prospecting prospects.

Figure 14- 13 "Three Sources" Metallogenic Prediction Map of North Hebei-North Liaoning Gold Deposits.

Theory of metasomatic hydrothermal mineralization: evidence for the genesis of hydrothermal deposits

Table 14-4 "Three Sources" Prediction Area of Gold Deposits in Northern Liaoning-Northern Hebei Region

It can be seen from the metallogenic model map of the three-source hydrothermal area of gold deposits that the whole area is divided into 1 1 sections, of which six sections (three single source areas and three secondary source areas) usually have no gold deposits, and five three source areas all have gold deposits, but the mineralization degree is different. In areas with strong mineralization, there are more large-scale deposits, as shown in Figure III- 1 and III-3; In areas with weak mineralization, the number of deposits is small and the scale is small, such as ⅲ-5. Ⅲ-2 and Ⅲ-4 are moderately mineralized.

The forecast areas belonging to ⅲ- 1 combination type include Shangying-Liujiakou, Lijiawopu-Gudao, Chimney-Longhua, Zhouzhangzi-Xingganhe, Da Qiao, Zhangdang-Huangqizhai, Haitang Mountain, Xiamanjing-Datuchengzi, Beizhen, Jinxian-Niangniang Palace and Erlong-Chijiazhangzi.

Ⅲ-3 combined prediction areas include Miyun in Beijing, Fengning in Hebei, Shanhaiguan, Fuxin, Yiwulu Mountain, Jianping in Liaoning, and possibly Luanping, Chengde and Qian 'an.

Ⅲ-2 combined prediction areas are Dabiandaozi, Sihuadingzi, Zhengdingzi, Dayingzi, Miliyingzi, Jianping and Suizhong in Liaoning, and Funing, Zhouzhangzi and Miaozhangzi in Hebei.

Ⅲ-4 combined prediction areas include Wazidian in Hebei, Kelegou, Chaoyang Bay, northern Fengning and northern Longhua, Shenjiagou (Ningcheng) in Liaoning and Montenegro.

Ⅲ-5 combined prediction areas include Longmenshan (Suizhong), Xitaijian (Xinglong), Pianqiaozi (Chengde), Xifengzhai (Chicheng), Xiadian (Pingquan), Baicaoling (Pingquan), Fujiagou and Tieyingzi (Jianping) in Liaoning.