During this period, intrusive rocks distributed in northeast-east direction in the form of compound bedrock and rock strands, invaded Tangjiazhuang Group, Jiaodong Group and Guandiwa Superunit, and left inclusions of different sizes in them. It was cut by the unconformity-ductile shear contact between the Proterozoic Jingshan Group and the Fenzishan Group, invaded by the Proterozoic and later intrusive rocks, and covered by the Mesozoic Cretaceous stratigraphic unconformity. Rock types: ultrabasic rock-basic rock in the early stage, and tonalite-pyroxene-granodiorite TTG rock series in the middle and late stage, which experienced the superimposed transformation of amphibolite facies metamorphism and ductile deformation, forming a set of gray granitic gneiss and plagioclase amphibolite, with extremely developed stripes, bands and gneiss structures. It is divided into 9 units and merged into Ma Lian Zhuang Chao Unit (3 units) and Qixia Super Unit (6 units). The former is small and scattered, while the latter is large and wide (Table 2-2).
1. Mali Zhuang Chao forces
Superunits are widely distributed and scattered, relatively concentrated in Malianzhuang, Nanlan and Rizhuang in Laixi, Qixia Daoxi, Macheng, Luanjiazhai, Sikou, Dawujia, Qishan Store and Shansunjia in Zhaoyuan in Laizhou. The scale is not large, and the largest Luanjiazhai rock mass has an area of only 6km2, with a total area of less than 52km2. Lenticular or irregular rock plants, rock tumors and rock walls are produced, and their distribution orientation is coordinated with the regional tectonic line. In the middle and late stage, they were invaded by Qixia superunit, leaving rootless inclusions in them, and Tangjiazhuang rock group inclusions were found in their rocks. It is a set of ultrabasic rocks that have undergone high amphibolite facies metamorphism and is divided into three units: Nanlan, Dawujiazhai and Luanjiazhai.
Table 2-3 List of average chemical composition and main parameter values of Archean intrusive rocks
The superunit belongs to metamorphic rocks such as yellow-green, gray-black, dark green serpentine, olive serpentine, amphibole gneiss and amphibole. Granular (columnar) crystal structure, blocky, flaky or banded structure. Superunit is composed of ultrabasic peridotite-amphibole-basic gabbro, olivine from existence to absence and plagioclase from absence from morning till night, and its evolution sequence is dominated by mineral components. According to the petrochemical parameters (Table 2-3), it is a Pacific strong calcium-calcium rock series, belonging to low-grade or undifferentiated basic and ultrabasic rocks. The consolidation index (SI) shows that the first two units are the direct crystallization products of mantle-derived ultrabasic magma, while the latter is the "I" type rock differentiated and crystallized by mantle-derived basaltic magma, but the big five SI values are contrary to the results of MgO/FeO molecular ratio. Accompanied by many groups, it is characterized by nearly east-west distribution, with ultrabasic rocks distributed on the outside and basic rocks distributed on the inside. It has the characteristics of orogenic roots and was emplaced by the active strong dome mechanism in the extensional tectonic belt under the north-south extension mechanism. According to isotopic age and macroscopic comprehensive analysis, it was formed in the early and middle period of Fuping in Neoarchean.
2. Qixia Super Unit
Figure 2-3 Distribution of Superunits such as Qixia, Linglong and guojialing.
1. Quaternary; 2. Cretaceous; 3. Penglai Group; 4. Fenzishan Formation; 5. Jingshan Group; 6. Weideshan Super Unit; 7. guojialing Superunit; 8. Wendeng Superunit; 9. Linglong Superunit; 10. Rongcheng superunit; 1 1. Double-top superelement; 12. Qixia superunit; 13. Shangzhuang rock mass; 14. North cut rock mass; 15. Jia Cong rock mass; 16. Qujia rock mass; 17. Fanjiadian rock mass; 18. guojialing rock mass; 19. Zetou rock mass; 20. Geological boundary; 2 1. Unconformity boundary; breakdown
The superunit is widely distributed in Zhaoyuan, Qixia, Laiyang and the northwest of Laizhou, east of Zhaoping fault, west of Taocun-Doushan fault, north of Jiaolai basin, and also found in southern Laizhou (Figure 2-3). The scale is relatively large, with a total area of about 152 1km2. This is the main lithology of Jiaodong Group and the core of Qixia anticlinorium. Superelements are in the form of composite bedrock and rock strains distributed in the east-west direction. Macroscopically, it is an ancient gneiss dome, with early units in the middle and late units distributed on its edge or outer edge, which is narrow in the north and wide in the south. The distribution of Shentang people in Laizhou is concentric and annular, contrary to the former, with the middle being late and the edge being early units. It intruded into Tangjiazhuang, Jiaodong rock group, Guandiwa and Zhuang Chao unit in Ma Lian, and existed in the form of residual inclusions with different sizes and shapes. It was in contact with the unconformity-ductile shear caprock and ductile shear structure of Proterozoic Jingshan Group and Fenzishan Group, and was also cut by Proterozoic-Mesozoic intrusive rocks, and was later destroyed by brittle fracture. It is a TTG series granite composed of tonalite-pyroxene-granodiorite. In some areas, it has undergone the superimposed transformation of amphibolite facies metamorphism and ductile shearing, forming a set of gray granitic gneiss series with developed banded, banded and gneiss structures. It is divided into six units (Table 2-2): Huilong Mine, Xinzhuang, Lujia, Letu Mine and Jenny Lanweiguang, in which Letu Mine is the smallest (3km2), Lujia the smallest (30km2) and Huilong Mine the largest (600km2). Pulsating or surge contact relationship between units. The rock is gray-dark gray, with medium-fine grain (columnar) crystal structure or scaly granulite gneiss structure, resembling gneiss, striped and banded structure, and is gray granitic gneiss macroscopically with uniform lithology.
From morning till night, the rock type of the superunit changes from tonalite to adamellite to granodiorite, and the overall chronological-potash feldspar increases, while plagioclase and dark minerals decrease, reflecting that it is an evolutionary sequence composed of minerals.
The main parameters of petrochemistry in Table 2-3 reflect that Rietmann index (σ) is 1.0L ~ 2.64, of which most of < 1.8 are Pacific calc-alkaline rock series, with a transition from calcium to calc-alkaline; Differentiation index (DI) is 67.69 ~ 8 1.55, and most of them are below 80, belonging to moderately differentiated intermediate-acid rocks. The overall trend of K/Na ratio is from low to high, which belongs to endogenetic syntectic granite magma. A/NKC > or < 1. 1 accounts for half, which is between the transitional types of "I" type and "S" type granite. The molecular ratio of FeO/MgO is 0.54 ~ 1.63, δ EU >; 0.7 is mantle-derived granite, and the above parameter values reflect that Qixia superunit is an "I" type and an "S" type transitional granite, in which the granite magma differentiated from mantle-derived basaltic magma assimilates molten crust-derived materials and forms an incompletely transformed syntectic granite slurry. There are a large number of dark rock residual inclusions in the field, which also shows its magmatic characteristics.
As mentioned above, the distribution characteristics of each unit of Qixia supercell, the early unit in the middle is a strong dome-shaped positioning mechanism; Comprises a later unit, and the edge with a directional structure is also an expansion positioning mechanism of a powerful hot air balloon.
The relationship between Qixia superunit and field plastids and its isotopes are mostly above 2500Ma, suggesting that it was formed in the middle and late Neoarchean. It is worth mentioning that the superunit is closely related to gold mineralization, and the surrounding rocks of all gold mining areas have traces of their lithology. It is also one of the "original source rock series" of gold.