Fortune teller's roots are tied to the bottom of the river. _ Fortune teller says roots are tied to the river.

Magmatic activities in the study area are very intense and frequent. It occurred from early Paleozoic to late Paleozoic, mainly in late Paleozoic. Magmatic activity is not only characterized by volcanic eruption and overflow which are widely developed in different periods, but also by extensive intrusion from ultrabasic rocks to basic, neutral, moderately acidic, acidic and alkaline magma. Late Paleozoic magmatism, whether volcanic magmatism or intrusive magmatism, is closely related to the mineralization of precious metals, nonferrous metals and rare metals.

I. Volcanic rocks

The distribution of volcanic rocks is strictly controlled by long-term active deep fault zones or regional fault zones; According to the spatial distribution and accumulation law of volcanic rocks in different periods, the volcanic rocks in the study area can be divided into four volcanic belts from north to south, namely, arman Taivolcanic belt, Yemaquan-Santanghu-Naomaohu volcanic belt, Karamaili volcanic belt and Jiangjunmiao block volcanic belt. Here is a brief introduction.

(a) Mount Tai in arman

Devonian marine volcanic rocks are mainly developed in arman-Thailand volcanic belt. Volcanic rocks are developed from basic, neutral to acidic, mainly intermediate basic rocks, and Rietmann index is between 1.8 ~ 9. The main rock types include olivine basalt, andesite basalt, rhyolite and tuff, volcanic agglomerate, etc. Rhyolites are mostly distributed in the middle of volcanic belt, and basalts are mostly distributed near marginal faults. Volcanic rocks in the middle Variscan (Carboniferous) mainly include basalt, pyroxene andesite, andesite and a small amount of dacite. Volcanic rocks in the late Variscan period are mainly distributed in the area of Wulanguhe River, mainly andesite, basalt and a small amount of rhyolite, with relatively weak volcanic activity.

(2) Yemaquan-Santanghu-Naomaohu volcanic belt

Located in the south of Yemaquan block and the north of Kalamaili suture line, its structural division is equivalent to Laoyaquan-Santanghu island arc in the early Late Paleozoic, and the middle and late Ordovician volcanic rocks are only exposed in the area of Kaokeserge Mountain. The bottom is volcanic eruption facies coarse pyroclastic rock, with upward detritus decreasing and lava increasing. The lower part is dominated by andesite, and the upper part is dominated by dacite. The eruption intensity is high, and the eruption environment ranges from shallow sea to deep sea. Devonian volcanic rocks are characterized by multi-center eruption. From west to east, lithology changes from intermediate acidity to intermediate alkalinity, which reflects the changing process of sedimentary environment from shallow sea to deep sea trough. Middle and late Devonian volcanic rocks are widely distributed in belts, and volcanic activity is mainly marine eruption. From west to east, lithology changes from basic to acidic. In the early Early Carboniferous (dune stage), volcanic activity was dominated by strong intermediate-acid volcanic eruption (overflow), forming a set of neutral and acidic pyroclastic rocks with a small amount of intermediate-basic lava. Compared with dune volcanic rocks, the volcanic rocks in the middle of Early Carboniferous (wei county period) changed obviously, and the volcanic rocks controlled by faults were mainly land-sea alternating volcanic rocks. Volcanic rocks in the late Early Carboniferous (Shelpukhoff period) are mostly the products of volcanic activity in the late Paleozoic plate subduction collision or post-orogenic period, mainly continental volcanic eruption. Formation of continental volcanic rocks from basic, neutral to acidic. The volcanic rocks in the middle and late Carboniferous basically inherited the characteristics of volcanic activity in the late Early Carboniferous, mainly terrestrial volcanic rocks. Early Permian volcanic rocks are mainly distributed in Santanghu area, mainly acidic rhyolite with andesite, followed by acidic pyroclastic rocks, all of which are products of continental volcanic eruption.

(3) Kalamaili volcanic belt

Karamaili volcanic rock belt refers to the volcanic rock development area located in the south of Kamsite-Sujiquan line and north of Karamaili fault, which is distributed in a narrow strip shape. It is mainly composed of middle and late Devonian and early Carboniferous volcanic rocks. There are two volcanic rocks in this area. One is the volcanic-sedimentary formation closely related to the ophiolite melange composed of basic and ultrabasic rocks in Karamay, which is mainly composed of basalt, spilite, interbedded quartz porphyry and spilite, tuff, deep-water purple argillaceous rocks containing radiolarians and siliceous rocks. The second type is the Early Carboniferous-wei county volcanic rocks directly covering the ophiolite melange belt. Nanmingshui Formation and Qingshui Formation of Lower Carboniferous are a set of intermediate-acid pyroclastic rocks with a small amount of intermediate-basic lava.

(4) Volcanic rock belt of Jiangjunmiao block

Volcanic rocks in this zone are mainly distributed in Shuangjingzigou and Jinshangou on the south side of Karamaili. The volcanic rocks in Batamayi mountain area are mainly andesite, followed by basalt mixed with a small amount of rhyolite, perlite and pyroclastic rocks, which were mainly formed in the late Early Carboniferous, followed by the middle and late Carboniferous. In short, the volcanic eruption in this area is mainly continental neutral volcanic rocks, with thick volcanic rocks and well-preserved volcanic institutions.

Second, intrusive rocks

(1) Basic-ultrabasic rock assemblage, mainly ultrabasic rocks and some basic rocks.

Li (1998) called this basic-ultrabasic rock assemblage "ultrabasic rock basic complex in ophiolite suite", which mainly distributed in the north side of Kalamaili deep fault zone and the north side of arman fault zone, forming Kalamaili ophiolite melange zone and Tazaheba ophiolite melange zone in arman respectively.

The rock types of Kalamaili ophiolite melange belt are mainly plagioclase peridotite, followed by dunite, monoclinite peridotite and plagioclase peridotite. Petrochemical characteristics: MgO content is 34.3 1% ~ 4 1.53%, TiO 2 content is mostly less than 0.03%, and M/F is 7 ~ 10.2, mostly greater than 8. It belongs to magnesium ultrabasic rock, which is equivalent to ultrabasic rock at the bottom of ophiolite suite. Some rock masses have been chromized. In the wild, ultrabasic rocks invaded the Middle Devonian. According to the research of Li et al. (1990), the Nanmingshui Formation of the Lower Carboniferous is directly superimposed on the ophiolite melange, indicating that it was formed at the end of the Middle Devonian when the oceanic crust was closed.

The ultramafic rocks in the Tai-Zhaheba ophiolitic melange belt in arman are mainly plagioclase peridotite, followed by dunite and pyroxenite, with a small amount of pyroxenite and gabbro. They are dismembered mixed bodies, widely distributed in the Middle Devonian, and a little distributed in the Upper Devonian and Lower Carboniferous. It is speculated that it was mainly formed in the Middle Devonian.

(2) ultrabasic rock-basic rock assemblage, with basic rocks as the main part and a small amount of ultrabasic rocks.

Plum (1998) is called calc-alkaline ultrabasic rock. It is mainly distributed in the bitter water of Halatongke in the north of East Junggar and Karamay in the north. Taking Halatongke mining area as an example, its rock types are mainly gabbro, olivine syenite and syenite, with a small amount of neutral diorite. A small amount of plagioclase amphibole and plagioclase biotite amphibole are seen locally. Rock mass is well differentiated and can be divided into three facies zones. From bottom to top, there are diorite facies, biotite amphibole syenite facies and biotite amphibole olivine syenite facies. There is also a layer of diabase facies wrapped in the crust of the rock mass, and the isotopic dating of the rock mass shows that its formation age belongs to the late Variscan period. Rb-Sr isochron age is 28 1 ~ 298.6 Ma, and K-Ar age is 273 ~ 306 Ma. Nickel-copper mineralization is mainly concentrated in the middle and lower part of the rock mass, mainly occurring in olivine phase and syenite phase.

(3) Granite assemblage

Except for a small amount of calc-alkaline granite intrusion in the late Caledonian, granite activities were mainly concentrated in the late Paleozoic Variscan period. Granites in this period are widely distributed in the study area, including three granites in different eras. Their rock types are diverse, and their tectonic environment and genetic attributes are also different. According to the special research results of "Eighth Five-Year Plan" and "305" project 85-902-03-04, granites of different genetic types in different periods in the study area can be divided into six categories and formed in different tectonic environments (Table 1-2). It can be seen from the table that all kinds of granites belonging to different ages and origins are unified into a complete granite evolution system. In this unified evolution system, the tectonic environment of granite formation plays a leading role. A certain mineralization is always closely related to a certain granite rock assemblage, which belongs to a certain granite genetic type, and a certain granite genetic type finally belongs to a certain granite structural type.

Table 1-2 Comprehensive Correspondence Table of Various Granites in East Junggar Region

Among them, the most obvious mineralization is A-type (alkaline) granite, Cordillera I-type granite and I-type granite (a series of characteristics are similar to Cordillera I-type granite) formed by intraplate deep faults or A-type subduction orogeny. The former is closely related to tin mineralization, while the latter two are closely related to gold, copper, iron and molybdenum mineralization. The focus of this topic is the formation of intermediate-acid subvolcanic complex, which includes the last two types of I-type granite in the study area. Their common feature is that their rock assemblage belongs to the category of granite rocks, but their genesis is closely related to continental volcanism in the same period, which is the product of continental volcanism in a specific tectonic environment. They are an important transitional type between plutonic magmatism and volcanic magmatism. Including China, they are also extremely important metallogenic magmatic formation in the world. Many important precious and nonferrous metal deposits in the world are related to it; China is no exception, especially in the eastern part of China in the Pacific Rim metallogenic belt.