What are the types of metallogenic processes and metallogenic stages?

In the process of metallogenic formation, a variety of complex geological phenomena have been formed, and the mystery of the metallogenic process can be solved through the first understanding of these geological phenomena. The classification of metallogenic processes can be divided into the following categories, namely, metallogenic processes related to weathering and sedimentation, metallogenic processes related to magmatism, metallogenic processes related to hydrothermal processes, and metallogenic processes related to metamorphism.

1. The metallogenic process related to weathering and sedimentation forms various sedimentary deposits, and the minerals involved mainly include iron, manganese, aluminum, phosphorus, potash, rock salt, coal, oil shale and other minerals.

2. The metallogenic processes related to magmatism can be divided into two categories related to volcanic eruptions and magmatic introsions, among which the metallogenic processes related to volcanic eruptions are mainly divided into marine volcanic mineralization and continental volcanic mineralization. The metallogenic process related to magmatic intrusion refers to various types of deposits formed directly from the magmatic melt during the process of magmatic crystallization differentiation or melting, including ultramafic chromite deposits, mafic ultramafic copper-nickel sulfide deposits, vanadium titanomagnetite deposits, rare earth, rare and scattered ore deposits related to granite sub-minerals, etc.

3. The metallogenic processes related to hydrothermal processes mainly include magmatic hydrothermal deposits. The hydrothermal mineralization related to magmatic intrusion occurs after the rock mass intrusion, and the ore-forming fluid forms agglomeration and precipitation mineralization. This is mainly related to the material differentiation during the cooling of magma.

The volatiles mainly water-based carry a large amount of dissolved salts and metallic elements to escape from the magmatic system to form a hot water solution after the magmatic period. The volatile phase is separated from the molten slurry being crystallized, and constitutes a complex system of gas phase (or aqueous solution phase) melt phase crystal phase differentiation in a high-temperature and high-pressure system. Including skarn-type deposits, porphyry deposits, medium-high temperature hydrothermal tungsten-tin ore, medium and low temperature hydrothermal gold ore, copper-lead-zinc ore.

4. The metallogenic processes related to metamorphism include "metamorphism", "becoming" and metamorphic hydrothermal mineralization. Metamorphic Bishuhu deposit refers to the original mineralization that has formed the ore body, and after metamorphism, the original mineral composition of the ore body and the characteristics of the spatial separation of the ore body have been changed, such as marine jet sedimentary metamorphic iron ore; Turning into an ore deposit means that the original composition is not a deposit, and the deposit is formed after regional metamorphism, such as graphite ore, talc, magnesite, etc.; Metamorphic hydrothermal deposits refer to the main body of ore-forming fluids produced in the process of metamorphic dehydration, and the minerals are also likely to come from the surrounding rock strata, such as orogenic gold deposits are typical metamorphic hydrothermal deposits.

According to the metallogenic specificity of the magmatic rocks in the area, the ore control structure and the hydrothermal activity period, the main metallogenic stages of gold deposits in Jiaodong area are divided into three stages and five metallogenic stages. Due to the differences in tectonic activities in different stages, the development degree of each metallogenic stage in each deposit is different.

1.Before the metallogenic period.

For the first stage:

1) Quartz stage of golden pyrite containing Wangjia: the main symbiotic mineral is quartz, and there is a small amount of pyrite.

2.Metallogenic period.

It can be divided into three phases:

2) Gold-quartz pyrite stage: the main symbiotic minerals are pyrite, quartz, and a small amount of sericite, natural gold, etc.;

3) Gold-quartz polymetallic sulphide stage: the main symbiotic minerals are pyrite, chalcopyrite, galena, quartz, etc., and there are a small amount of sphalerite, silver-gold ore, and natural gold;

4) Gold, silver, quartz polymetallic sulfide stage: the main symbiotic minerals are galena, sphalerite, quartz, etc., and there are a small amount of chalcopyrite, pyrite, gold-silver ore, silver-sulfur double salt minerals.

3.After the metallogenic period.

There is only one 5 stages:

5) Silver quartz polymetallic sulphide stage: the main symbiotic minerals are galena, sphalerite, quartz, etc., and there are a small amount of chalcopyrite, natural silver, and pyroxene.

In addition, there is the epigenetic phase.

The specific mineral symbiotic assemblages and generation sequences of the above periods are listed in Table 6-38, among which the gold-quartz polymetallic sulphide stage and the gold-quartz pyrite stage are the main gold-forming stages.

Table 6-38 Metallogenic period and mineral generation sequence of Jiaodong gold mine.

Continued surface spallation.

The formation of the Dachang tin polymetallic deposit with Yanshan.

It is related to the middle and late cage box cover compound rock mass, and is restricted by multiple periods of magmatic activity, tectonic movement and metallogenesis physicochemical conditions. According to the production characteristics of the ore body and the symbiotic combination of minerals, the formation of Dachang tin polymetallic deposit is divided into two metallogenic periods and five metallogenic stages, namely the skarn zinc (copper) ore metallogenic period and the tin polymetallic metallogenic period.

1.Metallogenic period of skarn-type zinc (copper) deposits.

The hidden cage lid compound rock mass of Dachang invades the middle and late Devonian mudstones.

In marl and limestone formations, skarn and angular lithification occur in the contact between the rock mass and the surrounding rock. Sulfide.

The metasomatized skarn minerals form zinc (copper) ore bodies, which are further divided into two metallogenic stages:

1) Early skarn lithification stage: It can be further divided into two sub-stages: the formation stage of anhydrous skarn minerals, which forms garnet, runesite, wollastonite and diopside.

Wait; The stage of formation of hydrous silicate minerals, which form actinolite.

Tremolite, epidote, chlorite, and a small amount of axonite have smaller grain sizes than minerals formed earlier.

2) Sulfide formation stage: ore-bearing hydrothermal fluids metasomatize skarn minerals along the layer, forming dense massive, disseminated layered and layered zinc (copper) ore bodies. In terms of the symbiotic assemblage and metasomatism of minerals, it is further divided into two sub-stages:

In the early sulphide stage, mainly pyrrhotite.

The arsenite-iron sphalerite assemblage often shows the formation of wollastonite and runese in the early stage of pyrrhotite metasomatization. Late sulphide stage of Mozhaoji: dominated by pyrite-chalcopyrite-iron sphalerite-galena assemblage.

2.Cassiterite-sulphide mineralization.

The composition of ore minerals in cassiterite-sulfide ore body is complex, mainly cassiterite, pyrrhotite, pyrite, arsenite, iron sphalerite and sulfur minerals, etc., and gangue minerals include quartz and calcite.

Potassium feldspar, tourmaline.

and sericite, etc. According to the production characteristics of the ore body, the interspersed metasomatism relationship and the symbiotic combination of minerals, the formation of tin ore body is divided into three metallogenic stages

1) Cassiterite-sulfide (mainly pyrite and pyrrhotite)-tourmaline-quartz stage, the main mineral assemblages are cassiterite, pyrrhotite, arsenite, pyrite, quartz and electroblind gaslite. Characterized by self-shaped quartz, needle tourmaline and arsenite.

2) Cassiterite-sulfide (mainly iron sphalerite)-sulfur salt-quartz stage, the main mineral assemblages are cassiterite, pyrite, iron sphalerite, sulfide minerals, quartz, sericite, etc., and cassiterite is bright yellow with poor automorphology.

3) Sulfide (small amount)-sulfur salt (small amount)-quartz (small amount)-calcite stage, mainly forming quartz-calcite veins, which contain a small amount of sulfide and sulfur salt minerals, and occasionally cassiterite minerals.