Ancient amphibolite metamorphic rocks are exposed in the shaft of Klei anticlinorium and Chalsk anticlinorium in Zalma area. Blue schist, albite-epidote-chlorite-glaucophane schist, garnet-epidote-glaucophane schist, amphibole schist, amphibole, eclogite and xenolith gabbro are distributed in the axis of Charles complex anticline. Silurian hard sandstone-siliceous siltstone-limestone-pisolite layer is exposed in Charles Kefu anticline. The bottom of Caledonian structural layer is dominated by early Cambrian jasper quartzite-spilite-siliceous rock, and the middle and upper parts are mainly carbonate-basalt formation and red molasse formation. Granodiorite intrudes into it.
Figure 2.4 Alteration assemblage and zoning of important porphyry copper deposits in Kazakhstan.
A— Koonad deposit (according to Kudryavtsev, 1997): 1— Late-stage syenite-sericite-muscovite with tourmaline locally; 2- silicified rocks; 3- timely-pyrophyllite-alunite; 4- mucilage; 5— Early timely sericite; 6- blue rock stratum; 7- potassium; 8- altered rocks containing corundum and andalusite;
9- timely-sericite-diaspore; 10-timely-sericite. B-Boshekuli deposit (according to Daukeev et al., 2002): 1- chlorite-sericitization; 2- silicification-sericitization; 3- biotite; 4- biotite superimposed chloritization; 5- potash feldspar; 6- silicide core; 7-undisturbed rock;
8— Hydrothermal breccia; 9— Ore body boundary. C- Akodoka deposit: 1- unaltered rock; 2- hydrothermal breccia; 3- silicification-sericitization; 4- biotite and albitization; 5- potassium; 6- medium potash feldspar; 7- strong potash feldspar-silicification; 8- silicide core; 9— Fracture; 10- ore body boundary
Devonian is widely distributed, in which volcanic rocks play an important role. In Charles recovery anticline, Devonian basaltic porphyrite-andesite porphyrite-tuff coexists with jasper and basalt. Devonian terrigenous clastic rocks contain serpentine detritus, and Frasi volcanic rocks directly cover serpentine. The volcanic flysch formation unconformity formed in Devonian covered the coastal-shallow-sea volcanic-sedimentary formation in the middle and late Ordovician. The middle Devonian volcanic sedimentary formation is not integrated on the Devonian volcanic flysch formation. The late Devonian developed the coastal volcanic molasses formation, which was covered by the early and middle Devonian volcanic sedimentary formation, and the area was not integrated. The Lower Carboniferous is a set of extremely thick volcanic-sedimentary rock series, which consists of andesite volcanic rocks, pyroclastic rocks and tuff. The bottom of the Upper Carboniferous is a coal-bearing molasse assemblage, which is dominated by continental red coal-bearing rock series. Permian is a continental sedimentary formation, including coal and oil shale layers. The deposit types include copper-nickel sulfide copper-nickel deposit, porphyry copper deposit, skarn iron-copper-gold deposit, marine volcanic iron-copper deposit, pegmatite rare metal deposit, shear zone gold deposit, epithermal gold deposit and vein deposit related to granite. Important deposits include Bakirchik super-large gold mine, Bolshevik large gold mine, Zhelek gold mine, Bale Dezard gold mine, Kuruzong gold mine, Grupo Kilog gold mine and Jumba gold mine, South Maksut copper-nickel mine, Koksa Yi gold mine, Alatas gold mine, Mambert Kere gold mine, Koshahara gold mine, Kuerzhenkuola gold mine, Bulkestai gold mine and the recently discovered Charlton Basshi iron-copper gold mine.
The Zalma-Sawur metallogenic belt can be divided into three metallogenic sub-belts, namely, the Sirektas-Salsazan copper-gold-rare-rare earth metallogenic sub-belt, the Zalma-Sawur copper-gold metallogenic sub-belt in the axial part and the Charleske-Manlak chromium-nickel-mercury-gold metallogenic sub-belt in the northeast. The mineralization of Zalma-Sawuer belt is controlled by the deep structure and the geological development characteristics of each structural belt. There are weathering crust type nickel-cobalt mineralization and linear fracture weathering crust type mercury mineralization in ultrabasic rock altered serpentine. Fe-Cu-Pb-Zn-Au-Mo mineralization exists in Charleske and Sirektas-Salsazan areas, which is related to Caledonian gabbro-diabase formation, basalt-andesite-rhyolite formation and granite-granodiorite intrusion. Layered ferromanganese mineralization related to basic volcanic rocks formed in early Variscan (Chalsk, Sawur and Manlak areas). Many Cu-Pb-Zn and Au-Ag deposits occur in altered basalt-andesite-rhyolite. The mineralization in the middle stage of Variscan is intense, including copper-molybdenum-gold-silver-arsenic-antimony-tungsten mineralization related to gabbro-diorite-granodiorite in the early Carboniferous and dacite-granodiorite in the late Carboniferous. Copper-nickel titanium mineralization (Maksutov-Sokratov deposit) occurs in late Carboniferous diabase. Mineralization of rare metals and rare rare earth metals related to granites developed in late Variscan includes Zalma complex containing tungsten and molybdenum and TAS-Espe complex containing rare metals in Clegg, ESPE, Kalaotkeli and Jelebegetieyi ore concentration areas.
Nickel-cobalt deposit occurs in Chalsk ultrabasic rock belt and extends along the watershed between Chaer River and Su River in Koetsier. Charleske chromite deposit occurs in serpentine, and the ore body is sausage-shaped and convex mirror-shaped. Copper-cobalt-nickel hydrothermal sulfide mineralization (antimony-nickel sulfide ore, arsenic-nickel ore) is found in talc magnesite schist. Mercury deposits are distributed in the Charlemagne-Gornostayev mercury belt and generally occur at the intersection of the northwest Charlemagne-Gornostayev deep fault and the transverse deep fault. Mercury mineralization is closely related to ultrabasic rock intrusions along the deep fault zone and to Triassic diabase porphyrite dikes along the deep fault zone. The Chalmercury deposit in Kaijiehill is controlled by faults and occurs in talc magnesite schist, altered peridotite and porphyrite. The primary enrichment of mercury is related to the serpentinization of ultrabasic rocks. The ore is breccia hydrothermal altered rock (talc magnesite schist, ultrabasic rock).
Hydrothermal and magmatic nickel-cobalt-copper deposits also occur in layered dark gabbro, gabbro and olivine. The ore body is a layered convex mirror, which is a dense massive disseminated nickel pyrite-chalcopyrite-pyrrhotite ore. This ore contains copper, nickel and a small amount of cobalt and silver. The typical representative of this formation is South Maksut deposit, which is located in the east of South Maksut gabbro in Zalma area and belongs to Zaltas syncline in structure. The rock mass consists of gabbro, gabbro, syenite and plagioclase peridotite. Copper-nickel sulfide deposits are distributed in the eastern part of South Maksut rock mass. Copper-nickel sulfide is mineralized into disseminated sulfide and small compact sulfide xenoliths in ore-bearing gabbro. The ore-bearing zone occurs in the lower part of the eastern part of rock mass, and its shape is consistent with the floor of rock mass.
Copper-molybdenum deposits are distributed at the intersection of faults and occur in granodiorite porphyry. The Kensai-Kaying porphyry copper deposit group in Korcyl occurs at the top of granodiorite porphyry dome. Mineralization is uneven, and the relationship between mineralized rocks and non-mineralized rocks is gradual. Ore bodies occur in the inner contact zone of late granodiorite porphyry (a few occur in the outer contact zone); Most mineralization is equiaxed, and its range is delineated according to granodiorite porphyry rock mass.
Kizil porphyry copper deposit is located in Sawuer island arc zone, where volcanic sedimentary rocks of Lower Carboniferous are exposed. Carboniferous basic subvolcanic porphyry intruded into the stratum, with diorite-gabbro in the early stage and quartz diorite-granodiorite-granite-light granite-granite porphyry in the late stage. Diorite porphyrite and diabase porphyrite dikes run through all these intrusions and altered mineralization zones. The deposit is located in the south wing of Kensai anticline and has a typical central volcanic mechanism (diameter 1.9 ~ 3 km). Except for the last diorite porphyrite vein, the rocks in the volcanic depression and its vicinity have undergone hydrothermal alteration, and the alteration intensity has increased toward the center. The alteration is albitization, chloritization, carbonation, sericitization and pyritization, with weak potash feldspar and biotite and widespread epidote. Advanced argillization, silicification and gypsum are developed in the center of volcanic institutions. A copper mineralization belt is delineated along the southwest edge of high-grade argillization, which is mushroom-shaped in plane. Mineralization is mainly related to timely veinlets. Primary ore is mainly composed of pyrite, chalcopyrite, molybdenite, chalcocite and celestite. There are jarosite, azurite, malachite and azurite in the oxidation zone.
The types of gold deposits include chronological pulse type, contact metasomatism type and sulfide gold mineralization in hydrothermal altered rocks. After the magmatic period, the Nb-Zr-RE formation developed in the area adjacent to the Zalma-Sawuer metallogenic belt and the Chengjisi-Talbahatai metallogenic belt, and its typical representative is the Upper Espe deposit in granite. The metasomatism forms anorthite-microcline-albite. Alkaline metasomatism of granite and pegmatite is accompanied by mineralization of rare metals. Orebodies occur in altered rocks and pyrochlore-zircon-sodalite granite at the top and outer contact zone of subalkaline granite, and are irregular plates. The main ore minerals are zircon, pyrochlore, fluorite, xenotime, bastnaesite, rutile and galena. Rare earth mineralization of pegmatite occurs in the inner and outer contact zone of subalkaline granite. The ore body is vein-shaped, and the ore minerals include zircon, pyrochlore, niobite and brown yttrium. Disseminated wolframite and molybdenite are developed in the greisen network veins and quartz veins at the top of the granite body. Skarn tungsten mineralization is found in hornfelted and skarnized carbonate rocks-terrigenous clastic rocks. Skarn is related to early Permian granite. Mineralized bodies are mainly composed of muscovite, Yingshi, topaz, fluorite and tourmaline, which are lenticular and veined. The main ore mineral is cassiterite, followed by arsenopyrite, pyrite and galena. Sulfide tin deposits occur in the outer contact zone between granite and sedimentary rocks. The "Memorial October" tin deposit is located in the south contact zone of Jielie Gejie-Granite, and the mineralization occurs in the east-west and northwest fracture zones. Ore bodies are mainly composed of fine cassiterite and acicular tourmaline aggregates.
Charlton Baxi iron-copper-gold deposit
Volcanic rocks in Sawuer Mountain area are exposed in the northern margin of West Junggar south of Erqis structural belt (Figure 2.5a). Middle Devonian Sawuer Mountain Formation is a set of island arc volcanic-clastic rock formations, while upper middle Devonian Brzin Formation is mainly composed of fine clastic rocks with a small amount of volcanic rocks, middle Devonian Yundukala Formation is a set of marine basic volcanic rocks and normal sedimentary clastic rocks, and upper Devonian Talbahatai Formation is a set of island arc turbidite volcanic flysch formation. Heishantou Formation of the Lower Carboniferous is a set of shallow-sea flysch terrigenous clastic rock formations, which are intercalated with volcanic rocks, and there are Berkdai gold deposits. Intrusive rocks are widely distributed in Sawuer Mountain area, among which granite is the most developed (Figure 2.5a). Zircon U-Pb ages of Tast pluton are 337±4Ma (Fan Yu et al., 2007), Sentas pluton is 328.2±5.7ma, and Walkensala pluton is 323.8±6.2ma (Yuan Feng et al., 2006). The zircon age of Quetas alkaline granite is 297.9±4.6Ma, and that of Qiaqihai alkaline granite is 290.7±9.3Ma (Zhou et al., 2006). Rb-Sr isochron age of albite porphyry in gold mining area is 294 13Ma (Li et al., 2000).
The late Paleozoic gabbro, diorite and granodiorite in Qierdun Bashi mining area invaded the volcanic-sedimentary rock layer of Brzin Formation (Figure 2.5b), and the mineralization developed in the contact zone between intrusive rock and volcanic rock. The lower part of Brzin Formation of Middle Devonian is composed of metamorphic sandstone, timely feldspathic sandstone, fine sandstone and siltstone, with sericite, tuffaceous siltstone and crystalline limestone lenses (including lily stems) appearing upward. The upper part is composed of metamorphic siltstone, argillaceous slate, metamorphic argillaceous rock, metamorphic sandstone and calcareous silty timely fine sandstone with limestone convex lens. Basalt-andesite-tuff exposed in the mining area. The phenocrysts in basalt are mostly clinopyroxene and amphibole, and there are few basic plagioclase. A small amount of phenocrysts are developed in tuff, and most breccias are andesite. Gabbro contains muscovite and calcite veins, chlorite and epidote, and common magnetite and apatite. Diorite is altered to some extent, amphibole is replaced by chlorite, and plagioclase is partially altered into sericite and calcite. Granodiorite is strongly altered.
Magnetization develops in the contact zone between gabbro and volcanic rocks. Ore types are divided into massive magnetite, dense disseminated magnetite, medium disseminated magnetite and sparse disseminated magnetite. The main metal mineral in the ore is magnetite, followed by chalcopyrite, hematite and pyrite. Gangue minerals include quartz, diopside, calcite, sericite and andradite. Wall rock alteration is mainly silicification, chloritization, carbonization and sericitization. In the inner contact zone between gabbro and volcanic rocks, gabbro has a porphyritic structure, and a large number of magnetite appears in altered clinopyroxene. Magnetite-Yingshi-andradite vein can be seen in the external contact zone of rock mass. Malachite grows in areas rich in magnetite. Sparse disseminated chalcopyrite was found in the vein.
Copper mineralization is mainly developed in hydrothermal breccia in diorite contact zone (for example, the contact zone between andesite and diorite can be seen at 40m in borehole 07/kloc-0, as shown in Figure 2.6a). Figure 2.6b shows the hydrothermal breccia in the diorite contact zone. The breccia is angular, all diorite breccia, cemented by calcite-quartz-chlorite-epidote, and a small amount of limonite is embedded in the cement. Figure 2.6c, D shows the hydrothermal breccia in the diorite outer contact zone, including andesite breccia and diorite breccia, and the cement is chalcopyrite-pyrite-sericite-chlorite-epidote.
Fig. 2.5 Geological map of Sawuer and its surrounding area in Xinjiang (a) and geological map of Chaerdun Bashi mining area (b)
The ore structure is dominated by veinlets, followed by filling structure. Ore minerals mainly include pyrite, chalcopyrite, galena, sphalerite, chalcocite, cadmium sulfide and malachite. Gangue minerals mainly include quartz, calcite, epidote, sericite, serpentine, chlorite, potash feldspar, albite and chlorite. The main types of wall rock alteration are pyrite sericitization, epidotization, potash feldspar, chloritization, silicification and carbonation. Epidotization and sericitization are closely related to chalcopyrite mineralization (Figure 2.6e, f). The chalcopyrite mineralization in diorite is mainly veinlets disseminated, while chalcopyrite veinlets and pores are mainly filled in andesite and tuff. Chalcopyrite+pyrite+sericite+potash feldspar+calcite+syenite is widely developed in hydrothermal breccia, accompanied by natural gold. At this stage, the alteration is veinlet-like, and it occurs at the initial stage of piercing. Disseminated chalcopyrite exists in calcite-sericite veins. Natural gold is round and wrapped by pyrite (Figure 2.7a, b). Pyrite-chalcopyrite-epidote-serpentine-chlorite-chlorite alteration is widely developed. The characteristic mineral is prehnite-epidote veinlets (chlorite locally), pyrite-epidote veinlets (0.1~ 0.5cm wide) are found in tuff, epidote almond bodies are developed in andesite, and chalcopyrite or pyrite is found locally. The cement of hydrothermal breccia is usually epidote and quartz, and chalcopyrite is disseminated. Chalcopyrite obviously accounts for early pyrite. The Yanshi-calcite vein obviously passes through the early epidote alteration, in which pyrite is authigenic and coexists with calcite and chalcopyrite, with Co content of about 1%, and sphalerite and galena are * * *, accounting for early chalcopyrite and enclosing early pyrite (Figure 2.7 d). The content of cadmium in sphalerite is relatively high (about 6%).
Fig. 2.6 Copper mineralization characteristics of the Charlton Bashi deposit.
A-07 1 borehole histogram; B— Hydrothermal breccia developed in diorite contact zone, and the sampling position is as shown in Figure A; C- hydrothermal breccia is developed in the outer contact zone of diorite; D-chalcopyrite-calcite-sericite veins in the contact zone between diorite and andesite have orthogonal polarization; E- chalcopyrite-prehnite-epidote vein, orthogonal polarization; F- isochron-calcite veins cross epidote alteration and orthogonal polarization. A B- albite; Cal—- calcite; CCP-chalcopyrite; CHL—- chlorite; EP- epidote; Prh—- prehnite; Py- pyrite; Qtz—- timely; Ser-sericite; Lm- limonite; CCP-chalcopyrite
Figure 2.7 Occurrence state of some metal sulfides in copper mineralization
A, b—— back scattering image (BSE) of pyrite wrapped with natural gold; C- chalcopyrite and epidote in almond body; ;
Sphalerite metasomatism chalcopyrite. A B- albite; Au- natural gold; Cal—- calcite; CCP-chalcopyrite;
Gn- galena; Py- pyrite; Qtz—- timely; SP- sphalerite; EP- epidote
According to the characteristics of mineralization, interpenetration, genetic combination of minerals, generation sequence and ore fabric, the copper mineralization process can be divided into hydrothermal stage and supergene stage (Figure 2.8). The hydrothermal stage can be divided into four stages: the first stage is mainly composed of quartz, albite, chalcopyrite, pyrite and calcite, and the ore minerals are disseminated. The second stage is composed of sericite, chalcopyrite, pyrite, potash feldspar, calcite, epidote, chlorite, albite, timely and natural gold, which is the main stage of copper mineralization, distributed in the contact zone between diorite and volcanic rocks in the form of reticular veins, or filled in hydrothermal breccia as a cement. Phase III is mainly composed of epidote, pyrite, chalcopyrite, serpentine, chlorite, chlorite, calcite, sericite and timely. Chalcopyrite is mainly distributed in veinlets or embedded in the outer contact zone of diorite, or filled in hydrothermal breccia as cement. Chalcopyrite is mainly distributed in the aggregate of chlorite and coexists with gangue minerals such as epidote, chlorite and calcite. Prehnite is the alteration product of amphibole and primary plagioclase (the false phase of amphibole and plagioclase is preserved), or it develops in vein shape, forming prehnite-Yingshi-calcite vein in the later stage of mineralization. Stage ⅳ is mainly composed of calcite, yingshi, galena, sphalerite, pyrite, serpentine, epidote and chlorite, and it runs through the early altered mineral aggregate in a vein shape (0.0 1 ~ 10 cm). The supergene mineral assemblage is Yingshi-calcite-limonite-malachite-chalcocite-light blue-cadmium sulfide ore. Limonite mineralization and malachite fossilization are important prospecting indicators. The secondary enrichment occurred in the supergene stage, and chalcopyrite metasomatized chalcopyrite, forming an annular edge, and some of it was associated with cadmium sulfide ore. Sulfur-cadmium ore occurs around sphalerite containing cadmium.
Fig. 2.8 Mineral assemblages of four metallogenic stages and supergene stages of copper mineralization in Qierdun Bashi mining area.
Gold mineralization is closely related to granodiorite body, and local intense alteration and mylonitization occur in granodiorite body. Wave extinction, core-mantle structure, dynamic recrystallization and banded structure are common in time. Recrystallized timely particles surround the residual mother crystal (Figure 2.9a). The residual spots appear in the form of seasonal fish, which has obvious wave attenuation. Pyrite is fractured (Figure 2.9b) and chalcopyrite is filled in the fracture (Figure 2.9c). Mineralization and alteration generally occur after mylonitization. Gold mainly occurs in pyrite-quartz veins, in which quartz shows obvious growth rhythm (Figure 2.9d), quartz gold is irregular (Figure 2.9e, F), and natural gold in limonite is round (Figure 2.9g), containing 88.35% ~ 89.82% of gold. Besides silver, natural gold also contains 0.35% ~. The late pyrite-quartz-sericite vein passes through the gold-bearing iron ore-quartz vein or fills the gap at the boundary of authigenic quartz crystal.