1. Ring (column) impact fracture system
The outer wall of the annular swell structure is subjected to strong impact, extrusion and ductile shear field, and the rocks are subjected to deep pressure impact, thermal metamorphism, even melting recrystallization, mylonitization, crushing extrusion and strong impact, resulting in a unique class of high-temperature impact minerals, such as cristobalite, coesite, tridymite, baddeleyite, Yingshi, plagioclase, pyroxene and wood stone. , as well as the unique impact of fragmentation and impact. Each cylinder has a main edge crack, which surrounds the powerful space of rock burst. It is not only the main transport channel of matter and power, but also the place where matter and original rock blend and gather in the deep. The main fault has been squeezed, expanded and broken many times, and it has become the guiding channel for mineral accumulation and secondary small rock tube (plant).
Figure 2-22 Main structural elements of circular surge
2. Secondary annular cracks
Due to the multi-stage upwelling of the annular surge structure, there may be many surges in the cylinder, so many parallel annular interfaces and faults are formed inside and outside the main edge faults. These secondary annular faults are the same as the main marginal faults in the sense of geological structure.
Sometimes there are several groups of parallel secondary annular cracks outside the main edge cracks, which are similar to the internal secondary annular cracks.
The vertical depth of the marginal fault plane is steep, and the original inclination and inversion of the whole (including rock mass) are rare, and the inclination or inversion of the ancient ring structure is rare. Therefore, attention should be paid to exploration, and it may have new geological significance if found.
3. Radial fracture
Due to the upward gushing and condensation contraction of magma, a radial fracture system is produced from the center outward. The extension distance of the main edge fault is related to the dynamic of the surge at that time. Generally, strong faults are obvious inside the circular surge and disappear in a short distance outside. The geological and mineral significance of radial faults is slightly less than that of parallel annular faults.
4.φ-shaped cracks
A pair of radial faults, strengthened and dislocated in the rotation and torsion of the rock pipe, split the circular structure into two semicircles. This kind of structure is very common, which is very helpful for ring structure identification, plastic reset and regional structure analysis. Many φ-shaped fault zones constitute the famous ductile shear zones of gold, silver, antimony and mercury.
5. Tangent fracture group
Due to the rotation and torsion of the ring structure, the tangent points of each group of parallel ring faults form tangential faults with different directions and extension lengths. The geological significance of this fault is similar to that of radial fault, the former is compressive and the latter is tensile and torsional. The amplitude of fault field is related to the scale, strength and period of annular surge structure.
6. Explosion field at the top and top of circular surge structure
Blasting space often exists in the upper part and top cover of circular water gushing structure (Figure 2-23). In the rockburst, the original surrounding rock and the deep-shallow mixed rock mass mainly form a rock blasting field, and the particle sizes of rock blocks, breccia and dust are quite different, and the composition is also very messy. A typical example is kimberlite pipe, which contains gold, copper, uranium and diamonds. The range, impact strength and geological superposition of this section are related to the structural strength and focal depth of rockburst. This space is directly related to the formation of solid, liquid and gas minerals, and it is also the basis for the intensity classification of geogenic strong explosion disasters. Rock explosion mainly includes in-situ explosion, crushing and recompression, as well as ejected rock blocks and fine dust, and its trace elements can show the depth and geological origin of the explosion.
Figure 2-23 Schematic diagram of the top of circular surge structure
7. Fold, nappe and gravity sliding structure of circular surge structure
The marginal depression of Laoyuanyong structure can accept volcanic-sedimentary formation, and when it is impacted again, it will form geosyncline folds with complete shape or even reverse overthrust and volcanic magma components transported by deep sources, forming geosyncline-type annular arc fold bundle, which was called geosyncline in the past from the macro structure. Flat basement and deep upwelling structure can form platform-type folds, the top of circular upwelling structure forms rift, and the fault-block sedimentary fold belt develops into basin-mountain structural system (Figure 2-24).
Figure 2-24 Folding, roughening and gravity sliding structure of circular surge structure
The island highlands uplifted by rockburst structure can cause huge rocks, rocks and even mountains to slide for a long distance. Under the impact of the Shandan earthquake, a Taohuala Mountain with a width of 10 km and a thickness of 1000 km moved by 10km, forming a Cretaceous basin in situ, and the steep surface can form a large-scale detachment nappe fold belt. The Keping Baicheng area on the southern slope of Tianshan Mountain in Xinjiang has formed nearly 200km long and dozens of them. On the southern slope of the Himalayas, the strike-slip nappe fold belt (plates 9-4,16-15,39-/kloc-0,39-14,40-14,
According to this principle, we have a profound understanding of the orogeny and uplift of the Qinghai-Tibet Plateau.
8. Overlay external structural system
The gushing body structure has a regular circular format with the gushing center as the core. The folds and faults introduced in the periphery of late superposition are all components of external superposition, which have nothing to do with the spewing movement and have no metallogenic significance, so they should be eliminated in the analysis.