The transformation of ore-forming materials from dispersed t

2019-05-15 10:57 admin
In the process of volcanic eruption and earthquake action, the original regional physical field has been significantly destroyed and reformed, and the strong crustal energy has been suddenly released, resulting in a tectonic-thermal anomaly zone, in which various ore-bearing fluids and mineralizing materials have been stimulated to activate, a large number of rapid movements, and obvious phase transformation has taken place in the fluid, which has transformed some mineralizing materials from dispersed state to concentrated state. The centralized transformation creates conditions.
 
In the classification of metallogenic systems, different tectonic dynamic systems are taken as the main basis for the classification of metallogenic systems. The metallogenic systems related to tectonic systems, such as extension, compression, strike-slip, uplift, subsidence, large-scale shear and meteorite impact, are divided. The time-space transition abrupt region (or time-space transition domain) within various tectonic systems has become the most favorable metallogenic site (Zhai Yusheng et al., 1999).
 
4. Multi-scale transformation of tectonic dynamic system
 
4.1 Global-scale Structural Institutional Transition
 
According to M. E. Barley (1992), the transition period from the end of the conjunction to the beginning of the decomposition of the paleocontinent is the peak period of the continental metallogenesis (Fig. 2). In geohistory, there were three Mesoproterozoic continents with a spacious area of 2 000-1 800 Ma, including Kiruna Iron Mine, Olympic Dam Cu-Au-REE Mine and Ti-V-Fe-bearing plagioclase, etc. in Yuanyuan 1 000-800 Ma, Neoproterozoic Supercontinent with clastic rocks, copper deposits and weathered Tanzhong uranium deposits, etc. and metal sulphide deposits in sedimentary rocks in 400-300 Ma Pan. Beds are most developed, including MVT (Mississippi Valley type) Pb-Zn deposits and Cu and Pb-Zn deposits in clastic rocks. The restriction of the opening and closing of ancient continents on regional metallogenic characteristics is a research topic worthy of attention. It can be seen that tectonic regime transformation on a global scale is the most important background for large-scale global mineralization.
 
That is, from NWW-SEE to NE-SW, and then with it
 
4.2 Regional Scale Structural System Conversion
 
During the Jurassic-Cretaceous, the tectonic system of North China block changed, and the siphon-induced ore fluid injection and mineral accumulation all belong to this scale.
 
4.4 Outcrop Scale Structural Conversion
 
When the extensional fissures occur in the rock strata, the fluid containing the material of the karst strata rapidly enters the fissures and precipitates the supersaturated material to form small veins (Alpine veins). For example, crystalline veins in quartz sandstone beds and Iceland veins in carbonate beds become orebodies when both quality and quantity are good.
 
4.5 Structural transformation on microstructural scale Yang Kaiqing (1984) studied a small siltstone anticline in detail under a microscope. From the microscopic phenomena, it can be found that the different deformation parts of the neutral surface as the interface fold have direct control over the distribution of material composition. Fold deformation is of great significance to the redistribution and formation of geochemical composition of rocks and minerals in various locations. In the upper part of the neutral plane, the quartz siltstone micro-folds (Fig. 3) shear between the two flanks, resulting in the formation of new sericite mostly residing in the plane, the development of parallel fold axis shear zones on the wing, and the formation of new sericite on the shear plane. The precipitated quartz migrates to the axis of the anticline in mylonitic shape and is concentrated in the longitudinal fracture of the fold axis and the saddle of the interlayer collapse (Gray et al., 1979). Once these newly-formed and migrated components have high gold-bearing background and are easy to disperse and migrate, different types of mineralization are developed in the wing and core, such as altered rock mineralization in the wing of fold and quartz vein mineralization in the core. Under the neutral surface is the crumpling area, which is generally a relatively closed diagenetic and metallogenic space and is not easy to cause long-distance material migration.

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