Regional Metallogenic Models

Abstract

The metallogenic belts (or regions) of the Sanjiang orogenic domain are divided under the ideas of systematic, hierarchical and correlated metallogenic geological-tectonic unit, based on the spatial–temporal structure of the MABT evolution → intracontinental convergence strike-slip → tectonic transformation orogenic process.

5.1 Division of Metallogenic Belts

5.1.1 Principles of Metallogenic Division

The metallogenic belts (or regions) of the Sanjiang orogenic domain are divided under the ideas of systematic, hierarchical and correlated metallogenic geological-tectonic unit, based on the spatial-temporal structure of the MABT evolution → intracontinental convergence strike-slip → tectonic transformation orogenic process. Then, the evolutionary-spatial configuration of MABT in the continental margin of Sanjiang orogenic belt and the metallogenic process (generation-development-migration) during the intracontinental convergence strike-slip tectonic transformation orogeny are restored, and the coupling relationship between the evolutionary history of metallogenic-structure environment and ore deposits types in the Sanjiang orogenic domain is revealed. The guiding principles of these works are: (1) plate tectonic-geodynamic theories; (2) geological records of sedimentation, volcanic formation, intrusive activities and metamorphic deformation in different tectonic-metallogenic unties; (3) spatial-temporal structure analysis of metallogenic-tectonic environment of relatively stable blocks and basins of different scales and volcanic-magmatic and ophiolitic mélange belts of different periods; (4) metallogenic regularity research, mineral exploration and prediction evaluation requirements; (5) the basic division principles of sedimentary space-time type composition and existence state caused by major tectonic events in special areas; (6) the reasonable location and properties of ore-bearing geological bodies in Sanjiang region which are screened and stripped by using regional metallogenic and geophysical methods.

5.2 Division Scheme of Metallogenic Belts

Metallogenic belt refers to the region or belt where deposits (or ore spots) are concentrated. In other words, the spatial distribution of mineral resource is controlled by certain geological structures, sedimentary formations and magmatic activities, which is generally related to tectonic units and/or tectonic-magmatic belts. Therefore, mineralization has common characteristics. According to the aforementioned division scheme of tectonic unites and tectonic-magmatic belts, combined with the distribution of deposits (ore spots), the Sanjiang5.1 region is divided into 10 important metallogenic belts. However, the metallogenic belt is equivalent to the third or fourth tectonic unit or tectonic-magmatic belt (Table , Fig. 5.1).

Table 5.1 Summary for the major deposits in 10 metallogenic belts, Sanjiang region, SW China

Fig. 5.1

a Tectonic framework of the Eastern Tethys; b distributions of major ore deposits and metallogenic belts in the Sanjiang region. Metallogenic belts: I: Ganzi-Litang Au metallogenic belt, II: Dege-Xiangcheng Cu-Pb–Zn-Ag polymetallic metallogenic belt, III: Jinshajiang-Ailaoshan Au-Cu-Pt metallogenic belt, IV: Jiangda-Weixi-Lvchun Fe-Cu-Pb–Zn polymetallic metallogenic belt, V: Changdu-Lanping-Pu'er Cu-Pb–Zn-Ag polymetallic metallogenic belt, VI: Zaduo-Jinggu-Jinghong Cu-Sn polymetallic metallogenic belt, VII: Leiwuqi-Lincang-Menghai Sn-Fe-Pb–Zn polymetallic metallogenic belt, VIII: Changning-Menglian Pb–Zn-Ag polymetallic metallogenic belt, IX: Baoshan-Zhenkang Pb–Zn-Hg and rare metals metallogenic belt, X: Tengchong-Lianghe Sn-W and rare metals metallogenic belt

• I. Gantzê-Litang Au metallogenic belt

• II. Dege-Xiangcheng Cu-Mo-Pb–Zn-Ag polymetallic metallogenic belt

• III. Jinshajiang-Ailaoshan Au-Cu-PGEs metallogenic belt

• IV. Jiangda-Weixi-Lvchun Fe-Cu-Pb–Zn polymetallic metallogenic belt

• V. Changdu-Lanping-Pu’er Cu-Pb–Zn-Ag polymetallic metallogenic belt

• VI. Zaduo-Jinggu-Jinghong Cu-Sn polymetallic metallogenic belt

• VII. Leiwuqi-Lincang-Menghai Sn-Fe-Pb–Zn polymetallic metallogenic belt

• VIII. Changning-Menglian Pb–Zn-Ag polymetallic metallogenic belt

• IX. Baoshan-Zhenkang Pb–Zn-Hg and rare metals metallogenic belt

• X. Tengchong-Lianghe Sn-W and rare metals metallogenic belt.

In a tectonic unit or tectonic-magmatic belt, due to the long-term, complex and multi-stage characteristics of geological evolution, the present tectonic units usually contain or preserve special deposits of different ages. Therefore, different deposit types and series formed in different evolution periods or stages can be formed as assemblage in the same metallogenic belt. On this basis, the complex multi-stage, multi-genesis, multi-source and multi-type metallogenic belts are formed in the Sanjiang region (Fig. 5.2).

Fig. 5.2

Comprehensive section of regional tectonics-metallogenic model in the Sanjiang MABT orogenic belt

5.3 Regional Metallogenic Models for the Major Sanjiang Metallogenic Belts

5.3.1 Ganzi-Litang Au Metallogenic Belt (I)

This belt is located in the eastern margin of the Sanjiang region and is developed on the Indosinian (Triassic) Paleo-Tethys combination zone and the Ganzi-Litang oceanic ridge volcanic-ophiolite mélange belt. This belt extends NW-SE for about 800 km from Zhiduo in the northwest, through Ganzi and Litang, and then to Muli in the southeast (Fig. 5.1). The Au mineralization is closely related to the Paleo-Tethys closure and the Cenozoic strike-slip faulting. The Au deposits are mainly distributed in the middle and southern sections of this belt and include many large and medium-scale ones, e.g., the Gala, Cuo’a, Xionglongxi, Ajialongwa and Suoluogou deposits (Zhang et al. 2012, 2015; Table 5.1).

5.3.2 Geological Evolution and Mineralization

The Ganzi-Litang suture zone, which coincided spatially with the gold belt, was formed by the Zhongzan-Shangri-La microcontinent rifting from the western margin of the Yangtze block to form a small oceanic basin in the Permian-Middle Triassic, and then the oceanic crust subducted westward under the Zhongzan-Shangri-La microcontinent in the Late Triassic, resulting in the closure of the oceanic basin and Yidun arc-Yangtze plate collision. The Dege-Xiangcheng (Yidun) island arc-basins, intra-arc-basins and back-arc-basins were formed to the west of the Ganzi-Litang suture zone. During the development of Ganzi-Litang oceanic basin, the Permian-Late Triassic MORB-type gabbro, diabase dykes, serpentinite, tholeiitic/picritic basalts, rift-type alkaline basalt, mafic-ultramafic cumulates, radiolarian chert and flysch sandstone and slate were widely developed, which constitute an ophiolitic mélange belt (Yan et al. 2020). The Yanshanian (Jurassic-Cretaceous) collisional orogeny along this suture zone occurred after the closure of the Ganzi-Litang oceanic basin at the end of Late Triassic, followed by the superimposed Himalayan strike-slip shearing, accompanied by the formation of many orogenic Au deposits, such as the Gala and Cuo’a orogenic Au deposits (Table 5.1; Hou et al. 2004; Li et al. 2010; Deng and Wang 2016).

Orogenic Au deposits in this belt are mainly controlled by the main fault zone and its secondary fault zones (esp. in fault bends), as well as in the middle section of the suture zone. Spatially, the mineralization occurs in intensely altered fault zone as vein type or altered rock type. Four gold-bearing alteration zones have been discovered (silicic, pyrite, sericite and carbonate) and present some unique characteristics in different ore hosts, which can be used as important prospecting indicators in this region (Huan et al. 2011; Deng and Wang 2016).

5.3.3 Regional Metallogenetic Model

The tectonic evolution of the Ganzi-Litang ophiolitic mélange belt resulted in the gold mineralization in this ore belt. During the formation of the Ganzi-Litang ocean basin, the Au, Fe and other ore-forming elements from the lower crust or mantle were initially enriched in the basic volcanic and sedimentary rocks, and this process continued until the closure of oceanic basin at the end of the Late Triassic (Fig. 5.3a). The Yanshanian orogenic activities formed a nappe-shear zone along the suture zone. With the evolution of metamorphic fluids, as well as the meteoric water-dominated hydrothermal activities, the volcanic-sedimentary rocks were fragmented, deformed and metamorphosed. The ore-forming elements were mobilized, migrated along and deposited in the nappe-shear zones (Li et al. 2010; Fig. 5.3b).

Fig. 5.3

Regional metallogenic model for the Ganzi-Litang metallogenic belt

5.4 Dege-Xiangcheng Cu-Mo-Pb–Zn-Ag Polymetallic Metallogenic Belt (II)

This belt is located near (west of) the Ganzi-Litang suture zone. It is an important ore belt developed in the Late Triassic Yidun island arc, which is consistent with the Changtai-Xiangcheng magmatic belt. It is an NNW-trending tectonic-volcanic belt with a length of 500 km from north to south and a width of 90–150 km from east to west (Fig. 5.1). The arc magmatic activities in the island arc orogenic period and the post-orogenic tectonic activities are intense in this belt. There are abundant mineral resources in the belt, with Pb-Zn-Ag deposits dominating the northern section (e.g., the Gacun, Gayiqiong, Xiasai, Xialong, Cuomolong etc.; Table 5.1) and Cu-(Mo) deposits (e.g., the Pulang, Xuejiping, Langdu, Chuncu, Lannitang porphyry Cu deposits and Hongshan, Xiuwacu, Relin, Donglufang, Tongchanggou porphyry-skarn Mo polymetallic deposits; Table 5.1; Li et al. 2011; Leng et al. 2018) dominating the southern section.

5.4.1 Geological Evolution and Mineralization

The Dege-Xiangcheng island arc was formed by the Late Triassic west-dipping subduction of the Ganzi-Litang Paleo-Tethys Ocean. Along the island arc belt, the regional uplift may have resulted in the tectonic paleogeographic pattern and various lithological lithofacies combinations. The belt experienced multi-stage of arc formation (compression setting), intra-arc rifting (extension setting) and arc reformation (compression setting). Recent studies have shown that the formation of these structures may be related to multiple subduction rollbacks and extensional settings (Li et al. 2017).

The Middle-Lower Triassic marine clastic rocks are inter-calated with carbonates and chert, and the Upper Triassic flysch is inter-calated with mafic-felsic volcanics and carbonates. Magmatic rock assemblages of three tectonic stages were developed in the Paleozoic: (1) Late Permian-early Late Triassic: volcanic passive margin (rifting) was developed, forming intraplate alkaline-transitional basalt and/or rhyolite assemblage. In particular, the Permian mafic volcanic rocks are geochemically comparable to the Emeishan flood basalt (Song et al. 2004); (2) Middle-Late Triassic: The Dege-Xiangcheng island arc began to develop, forming the andesite-dominated calc-alkaline volcanic assemblage and intermediate-felsic porphyry intrusions (Hou et al. 2004); and (3) Late Triassic: the Cuojiaoma-Daocheng batholith (dominated by calc-alkaline monzogranite and granodiorite) was formed. The Yanshanian-Himalayan (Cenozoic) tectonics superimposed the Cenozoic post-collisional granite, granite porphyry and related Cu-(Mo) polymetallic mineralization.

During the formation and development of Dege-Xiangcheng island arc, due to the steeper subduction angle and faster subduction velocity in the northern section, the extensional metallogenetic environment was formed in the northern section, while compressional metallogenetic environment was formed in the southern section of the Dege-Xiangcheng island arc (Li et al. 2010). Two tectonic environments mainly controlled three deposit types and ore metal assemblages: (1) in the northern section, extensive and multi-cycle bimodal volcanism (basalt and rhyolite) was developed, accompanied by the formation of Kuroko-type VMS deposits. The ore bodies mainly consist of a stratiform/lenticular upper part and a stockwork lower part. The ore metals in these deposits include Zn-Pb-Cu-Ag, and the mineralization ages are concentrated in the Late Triassic, such as the Gacun and Gayiqiong (Sichuan 210–230 Ma) (Table 5.1; Hou et al. 2001, 2003, 2004; Wang et al. 2013a; Dang et al. 2014; Xue et al. 2014); (2) in the southern part, a series of porphyry Cu polymetallic deposits was developed, such as the Pulang, Xuejiping, Chundu, Lannitang and Langdu (Li et al. 2006, 2011, 2017; Leng et al. 2010); and (3) in the Yanshanian post-collision extensional setting, the thickened lower crust may have delaminated and partially melting, forming extensive felsic magma emplacement into the Indosinian porphyries, consequently the Indosinian-Yanshanian intrusive complexes. Thus, there are many porphyry-skarn and granite-related quartz vein-type Mo polymetallic deposits distributed in this region, such as the Hongshan Cu-Mo (Li, et al. 2013; Peng et al. 2016; Gao et al. 2020), Xiuwacu W-Mo deposits (Liu et al. 2016; Zhang et al. 2017, 2020, 2021), Tongchanggou, Donglufang and Relin deposits (Liu et al. 2016; Li et al. 2017; He et al. 2018).

5.4.2 Regional Metallogenetic Model

Based on the coupling relationship between magmatic activities and mineralization, the Dege-Xiangcheng metallogenetic belt can be divided into northern section and southern section. Controlled by different tectonic backgrounds, VMS deposits were formed in the north extensional arc, while porphyry Cu polymetallic deposits were developed in the south compressive arc (Fig. 5.4a, b).

Fig. 5.4

Regional metallogenic model for the Dege-Xiangcheng metallogenic belt

Subsequently, in Late Yanshanian and Himalayan periods, collisional orogeny and strike-slip activities were developed in this region, respectively, which resulted in the formation of Mo polymetallic and structured altered deposits (Fig. 5.4c).

5.5 Jinshajiang-Ailaoshan Au-Cu-PGEs Ore Belt (III)

This belt is developed in the Jinshajiang-Ailaoshan suture zone and the MORB-type ophiolites of the late Paleozoic (Lai et al. 2014a, b; Xu et al. 2019a, b). It extends NW-SE from Zhiduo in the northwest, through Yushu and Batang and to Ailaoshan in the southeast. The belt is 20–40 km wide and thousands of kilometers long. The belt can be divided into Jinshajiang (mainly Cu) and Ailaoshan (mainly Au) sub-belts (Fig. 5.1).

5.5.1 Jinshajiang Sub-Belt

This sub-belt is mainly composed of fold-thrust belt in the western margin of Zhongzan-Shangri-La block and the low-grade metamorphic rocks in the Jinshajiang suture zone.

5.5.1.1 Geological Evolution and Mineralization

The Jinshajiang suture zone is sandwiched between the Jinshajiang and Yangla-Ludian fault zones. It is mainly composed of ophiolitic mélange, including: (1) MORB-transitional basic rocks formed during the oceanic basin opening process and Carboniferous-Lower Permian deep-water turbidites (Li et al. 2002); (2) intra-oceanic arc basaltic-andesitic rocks were formed during the west-dipping subduction of the oceanic basin, associated with the large-scale mineralization of the Yangla copper deposit (Table 5.1; Zhu et al. 2010; Yang et al. 2011; Li and Liu 2015). Furthermore, it is also revealed that ore-bearing felsic intrusive rocks have the characteristics of mantle-crust mixed magma source at the Yangla deposit (Zhu et al. 2010; Yang et al. 2011); (3) late Indosinian-Himalayan syn-collisional intermediate-felsic granitoids and the alkaline porphyries (strike-slip faulting stage) are closely related to Cu-Au ore deposits, such as Yangla, Tuoding and Tongjige porphyry-skarn mineralization in this period (Deng et al. 2014). The fold-thrust belt in the western margin of the Zhongzan-Shangri-La block is characterized by the development of imbricate nappes, detachment faults and klippe structures, accompanied by strong molybdenite mineralization, rheological fold, flow cleavage and dynamic metamorphism. The belt (over 600 km long) has many nonferrous metal deposits, such as the Tuoding Cu deposit (Mou et al. 1999).

The sub-belt experienced a complex multi-stage geological evolution. The Jinshajiang oceanic basin was formed during the middle Late Devonian to Early Permian and began to subduct westward in the late Early Permian, forming the Zhubalong-Yangla-Dongzhulin intra-oceanic arc and the Xiquhe-Gongnong back-arc-basin (oceanic crust basement) in the western margin of the arc. Strong sinistral shearing/napping from east to west occurred during the arc-continental collision and subsequent intracontinental orogeny after oceanic basin closed in the Late Triassic basin. Since the Late Triassic, under the background of collision between North China and Yangtze block together with large-scale strike-slip faulting between blocks, the development of various intermediate and felsic magmatic rocks and dikes as well as Cu-Pb-Zn mineralization had been superimposed (Ying et al. 2006; Deng et al. 2014). The distribution regularity of deposits in the Jinshajiang sub-belt could be summarized as: the VMS-type Cu deposits are mainly formed in the intra-oceanic arc volcanic rocks in the Jinshajiang ophiolite, while the Pb-Zn deposits are mainly hydrothermal vein type and occur in the thrust nappe and shear-detachment zones of the fold-thrust belt.

Regional Metallogenetic Model

The Jinshajiang oceanic basin may be formed in the Hercynian period, and the VMS mineralization occurred in the Middle-Upper Devonian submarine mafic volcanic-sedimentary sequences. Together with the deep-water turbidites, it formed the initial ore source bed and provided ore-forming materials for the sedimentary-hydrothermal superimposing deposits (such as the Yangla Cu deposit) under the magmatic hydrothermal events of the Early-Middle Triassic (Fig. 5.5a). The ophiolite provided initial ore-forming materials for the late tectonic altered-type Cu-Au-Pb-Zn mineralization.

Fig. 5.5

Regional metallogenic model for the Jinshajiang Cu-Pb–Zn metallogenic sub-belt

The intracontinental collision and nappe events occurred during the Yanshanian to Himalayan period in response to the India-Asia collision (Deng et al. 2016). The tectonic event may have formed the alkaline magmatic rocks that emplaced into the mélange belt, which also formed the skarn-/porphyry-type Cu-Pb-Zn polymetallic mineralization (Fig. 5.5b). The thrust nappe, strike-slip shear-detachment tectonism of the Himalayan period complicates the superimposition and transformation of ore deposits and ore bodies and forms hydrothermal vein-type Cu-Pb-Zn polymetallic deposits (Fig. 5.5c).

5.5.2 Ailaoshan Sub-Belt

This sub-belt is a complex nappe structure composed of the Ailaoshan basement nappe belt, Jinping slip unit and low-grade metamorphic rocks in the western margin of the Yangtze block (Fig. 5.1).

Geological evolution and mineralization

The sub-belt has experienced multi-stage geological processes. The Ailaoshan oceanic basin, which was formed by extension in the Late Devonian-Early Permian, has subducted westward and closed during the late Early Permian. Foreland depression basin was formed and molasse formation was accumulated during the subsequent collision process in the Late Triassic. There were strong nappe and sinistral strike-slip faulting westward during the late Yanshanian to Himalayan period (Li et al. 2010; Xu et al. 2019a, b, c, 2020). With the occurrence of large-scale strike-slip structure, alkali-rich porphyry intruded along the strike-slip zone and its secondary faults, forming porphyry-skarn Cu-Au deposits and Au polymetallic mineralization (e.g., the Beiya and Machangqing porphyry-skarn Au polymetallic deposits; Table 5.1; Yang et al. 2020a, b, c), and orogenic (also named structural-controlled alteration type) gold mineralization was also developed in the shear zone (e.g., the Donggualin, Jinchang, Laowangzhai and Daping deposits; Table 5.1).

There are three regional NNW-trending thrust faults are developed in this sub-belt, namely Red River (Red River), Ailaoshan and Jiujia-Mojiang. Among them, the Red River fault zone has undergone multiple tectonic phases and later (after 17 Ma) transformed into dextral strike-slip (Leloup et al. 2001; Li et al. 2010). There are four stages closely related to the formation of gold deposits: (1) the (quasi-)oceanic ridge-type volcanic-ophiolite belt during the formation of the oceanic basin is mainly distributed in the front nappe belt on the hanging wall of Jiujia-Mojiang fault zone, with intermittent distribution of more than 200 km, and forms the ophiolite mélange belt together with the deep-water turbidite sediments during Devonian-Early Permian (Lai et al. 2014a, b); (2) the island arc basalt-andesite assemblage formed during the westward subduction and closure of the oceanic basin, including the Permian basalt on the western side of the Ailaoshan and Mojiang fault zones; (3) the intermediate-felsic intrusions formed in the syn-collision stage, which were concentrated on the volcanic belt of Permian, formed the felsic intrusive batholith with banded distribution; and (4) formed under the collision-nappe tectonic background during the Yanshanian-Himalayan orogeny, the Ailaoshan granites, alkaline porphyries, strongly granitic rocks and lamprophyre intrusions have close temporal-spatial genetic link with gold mineralization (Xu et al. 2019a, b, c, 2020).

The mineralization of Jinshajiang-Ailaoshan alkali-rich porphyry belt is characterized by metal zonation. The northern part is dominated by Cu-(Mo-Au) mineralization (e.g., the Yangla, Tongding, Tongjige Cu deposits), and the southern part is transformed into Au-(Cu/-Mo) mineralization, such as Machangqing and Beiya super-large porphyry-skarn-type Au deposits with proven Au reserves of over 387 t (Table 5.1; Li et al. 2016a, b, c; Hou et al. 2017; Li et al. 2021; Wang et al. 2018). Most of these deposits have magmatic hydrothermal mineralization systems (Li et al. 2016a, b, c). The ore bodies are mainly distributed in the inter-layer detachment planes between different lithologies and the detachment faults connected with the Jinshajiang-Ailaoshan main faults control the morphology, occurrence and size of the ore bodies, as well as the distribution of alteration zones. Typical orogenic Au deposits in Ailaoshan include the Donggualin, Laowangzhai, Jinchang and Daping (Zhang et al. 2011, 2019; Deng et al. 2015; Zhou et al. 2016).

Regional Metallogenetic Model

This sub-belt has experienced several significant geological events since Hercynian (Xia et al. 2016). With the fragmenting of Ailaoshan oceanic basin in the Hercynian period, the deep-water turbidites and ophiolites formed the initial source bed of gold mineralization, with the zircon U-Pb isotopic ages of 400–300 Ma (Hou et al. 2003; Li et al. 2010; Fig. 5.6a). Some ore-bearing strata may have resulted in new ore-forming rocks (e.g., pyroxene diorite) under the remelting and reconstruction of subduction zone during the Late Hercynian-Early Indosinian, with zircon U-Pb isotopic ages of 285–200 Ma (Hou et al. 2003; Li et al. 2010; Fig. 5.6b). In response to the Himalayan orogeny events, dominantly sinistral strike-slip movements and widespread lamprophyre intrusions were developed in the Ailaoshan sub-belt. Accompanying with strike-slip nappe movements, meteoric water infiltration and deep fluid mixing process extracted the ore-forming elements from the source rocks and then transported into secondary shear tectonic zones and nappes, which resulted in the forming some ore deposits at the top of the tectonic convergence zones (Fig. 5.6c).

Fig. 5.6

Regional metallogenic model for the Ailaoshan Au metallogenic sub-belt

5.6 Jiangda-Weixi-Lvchun Fe-Cu-Pb–Zn Polymetallic Ore Belt (IV)

This belt is located in the volcanic arc of the Jiangda-Weixi-Lvchun continental margin between the Jinshajiang suture zone and Changdu-Lanping-Pu’er (Changdu- Lanping-Simao) block and is distributed along Jiangda-A'dengge-Nanzuo-Mojiang- Lvchun (Fig. 5.1).

5.6.1 Geological Evolution and Mineralization

The formation, development and mineralization of continental margin arc are closely related to the subduction of Jinshajiang-Ailaoshan oceanic basin and arc-continent collision in Paleo-Tethys. This belt is mainly composed of three secondary volcanic belts: (1) the Early-Late Permian Jiangda-Weixi-Lvchun arc related to subduction, which was formed by west-dipping subduction of the Jinshajiang-Ailaoshan oceanic basin beneath the Changdu-Lanping-Pu'er block (Fig. 5.7a); (2) the Early-Middle Triassic syn-collision magmatic belt related to the Jinshajiang oceanic basin closure, where intermediate to felsic magmatic rocks are formed (Fig. 5.7b); (3) the Late Triassic post-collisional rift-type magmatic belt related to crustal extension (Wang et al. 2001, 2002; Fig. 5.7c).

Fig. 5.7

Regional metallogenic model for the Jiangda-Weixi-Lvchun polymetallic metallogenic belt

Most important deposits (e.g., Laojunshan, Zhaokalong, Luchun, Chugezha, Hongponiuchang) were formed in the Late Triassic, many of which were modified/superimposed by the following Himalayan mineralization (Fig. 5.7d). There are some Fe, Cu and Pb-Zn-Ag deposits in this belt, together with some Late Triassic large gypsum deposits (e.g., Lirenka). The major deposit types include: (1) VMS deposits occurred in the Late Triassic rift-related volcanic rocks, such as the large-scale Laojunshan Pb-Zn deposit and the Zhaokalong Ag-Fe polymetallic deposit (Table 5.1; Feng et al. 2011; Li et al. 2016a, b, c; G.S. Yang et al. 2020a, b, c); (2) SEDEX deposits were hosted in Upper Triassic sedimentary rocks, such as the large Zhuna Ag-Pb-Zn polymetallic deposit; (3) porphyry- and skarn-type deposits were related to (ultra)-hypabyssal intrusions, as represented by the Triassic Jiaduoling Fe-Cu deposit; and (4) hydrothermal vein-/altered rock-type polymetallic deposits, such as the large Lirenka Pb-Zn deposit and Longbohe IOCG deposit in the Jinping terrane, which could be compared with the Sin-Quyen IOCG deposit in Northwestern Vietnam (Cui et al. 2006; Halpin et al. 2016; Liu and Chen 2019).

5.6.2 Regional Metallogenetic Model

During the formation of continental marginal arc, the Jinshajiang oceanic basin began to subduct westward in the late Early Permian and subducted under the Changdu-Lanping-Pu'er block, forming the Jiangda-Deqin-Weixi-Lvchun subduction-collision type continental margin arc in the eastern margin of the block. The magmatism is mainly calc-alkaline intermediate-basic to felsic, forming volcanic rocks and syn-collisional granitoids such as granodiorite, monzogranite, plagio-granite, diorite porphyrite and quartz diorite porphyrite (Li et al. 2010), which resulted in the formation of many porphyry- and skarn-type deposits (Fig. 5.7a, b).

During the post-collision extension in the Late Triassic, the continental margin changed from compression to extension, forming the superimposed rift basin and the associated VMS mineralization. Different degrees of basin development in certain sections and different stages of basin evolution controlled certain types of deposits. SEDEX-type Pb-Zn-Ag deposits were developed in the rift basin of the northern part of the belt. In the rift basin of the middle part of the belt, VMS-type deposits of the bimodal volcanic mantle felsic section were formed in the early stage of the basin extension. Lirenka-type gypsum deposits occurred in the shallow marine molasse in the late stage of basin evolution (Fig. 5.7c).

During the intracontinental collision orogenic stage from the Middle-Late Yanshanian to Himalayan, thrust nappe and strike-slip structures were developed in this ore belt. This may further upgrade and enlarge the existing deposits and lead to the formation of ultrahydrothermal altered rock-type polymetallic deposits inside the fault zone and its secondary fault fissures (Fig. 5.7d).

5.7 Changdu-Lanping-Pu’er Cu-Pb–Zn-Ag Polymetallic Ore Belt (V)

This belt is developed in the Changdu-Lanping-Pu’er Mesozoic back-arc-basin located between the Jiangda-Weixi-Lvchun Fe-Cu-Pb-Zn and Zaduo-Jinggu-Jinghong Cu-Sn ore belts. Two important deposit types have been discovered: porphyry Cu-Au-(Mo) deposits in the Yulong-Mangkang region and Pb-Zn-Ag polymetallic deposits in the Changdu-Lanping basin (Fig. 5.1).

5.7.1 Yulong-Mangkang Porphyry Cu-Au(-Mo) Sub-Belt

This sub-belt is located in the eastern part of the Changdu basin, adjacent to the northern segment of the Jiangda-Weixi arc. The famous Yulong super-large Cu deposit is developed in this belt (Spurlin et al. 2005; Yang and Cooke 2019; Yang et al. 2020a, b, c). The Cu-Au-(Mo) mineralization is associated with the Himalayan felsic porphyry intrusions, e.g., the Mamupu and Bada deposits (Table 5.1).

Geological Evolution and Metallogenesis

The porphyry Cu-Au-(Mo) deposits in the Yulong-Mangkang region are mainly hosted in Early-Middle Triassic clastic and carbonate rocks, inter-layered with felsic volcanics and Late Triassic-Cretaceous continental red beds. Most of the folds and faults in Yulong-Mangkang region are arranged in echelon, showing dextral shear. The Himalayan felsic porphyry intrusions were emplaced into Early-Middle Triassic volcaniclastic rocks. Porphyry Cu-(Mo) deposits in the region are related to monzogranite porphyries, such as the super-large Yulong porphyry Cu-(Mo) deposit (Table 5.1; Chen et al. 2020; Huang et al. 2020). Meanwhile, the porphyry Au-(Ag) deposits are mainly related to monzonitic and syenite porphyries, such as the Mamupu, Gegongnong and Gegongnong deposits (Zhang et al. 2012). The Cu-(Mo) and Au-(Ag) deposits developed in the Yulong-Mangkang region show porphyry-epithermal-type characteristics.

Regional Metallogenetic Model

The Yulong-Mangkang region is an important Himalayan tectonic-magmatic belt formed by the transitional rifting along the Jinshajiang strike-slip fault. During the India-Asia collision, pull-apart basins were formed around the steps of the Jinshajiang strike-slip fault zone, and the extensional setting led to the emplacement of alkaline (incl. potassic) magma, forming the Yulong-Mangkang porphyry belt. The porphyry intrusions not only provide the ore-forming fluids and materials, but also the essential heat for driving the circulation of ore-forming fluids (Fig. 5.8a, b; Li et al. 2010).

Fig. 5.8

Regional metallogenic model for the Changdu-Lanping-Pu’er metallogenic belt (Fig. b modified after Sillitoe 2010; Fig. c modified after Leach and Song 2019)

5.7.2 Changdu-Lanping Pb–Zn-Ag Sub-Belt

This sub-belt is developed in the Changdu-Lanping transtensional pull-apart basin resulted from the movement of Jinshajiang strike-slip fault. This sub-belt is located in the south of the Yulong-Mangkang porphyry Cu-Au-(Mo) sub-belt and west of the Weixi magmatic arc. The Changdu-Lanping sub-belt thins out in the center, and widens toward both ends (Fig. 5.1).

Geological Evolution and Metallogenesis

The Lanping-Pu’er basin in the mass has experienced three evolution stages in the block: (1) Basement formation stage. The Late Paleozoic Paleo-Tethys basin was opened, and the Proterozoic-Paleozoic metamorphic basement was exhumed outside the boundary fault of the Lanping-Pu'er basin. The Jinshajiang Ocean, which was a branch of Paleo-Tethys, separated the Western Yangtze block to the east from the Lanping-Pu'er basin to the west. The subduction of the Jinshajiang Ocean to the west and the Lancangjiang Ocean to the east led to the mutual subduction of both sides of the Lanping-Pu'er basin, resulting in the collision between the Baoshan-Sibumasu Terrane and Yangtze block in the Late Permian. During the Early-Middle Permian, strong orogenic activities may have resulted in the general absence of Middle-Lower Triassic strata in this region; (2) intercontinental basin evolution stage. This sub-belt experienced intracontinental extension, and the sedimentary cover was the alternating deposits of sea-river facies from Upper Triassic to Lower Jurassic since the Late Triassic. Until the Middle Jurassic, the Lanping region changed from intracontinental rift to intracontinental depression basin, which was filled with continental sediments from Middle Jurassic to Cretaceous; and (3) Basin strike-slip and uplifting stage. The Lanping basin experienced the evolution of basin development and strike-slip pull-apart basin opening in the Cenozoic. The sediments have the characteristics of closed lake basin environment, mainly developing gypsum-bearing red beds (Xue et al. 2007; Bi et al. 2019).

The Changdu basin basement is composed of Precambrian Jitang group and Youxi group. The Paleozoic sequence is scattered in this region, mainly Early Ordovician and Devonian-Permian clastics and carbonates. The Mesozoic sedimentary cover consists of Triassic pelagic carbonates with volcanic inter-beds, Jurassic pelagic carbonates and continental red beds and Cretaceous continental clastics. The orogenic belts on both sides of the Changdu basin were formed by megathrust event (the Jinshajiang and Lancangjiang fold belt) as the Paleozoic and Mesozoic strata were thrusted beneath the Proterozoic metamorphic basement in the eastern part of the Changdu basin in the Middle-Late Eocene, forming west-dipping nappe structures. In the western part of the basin, the Late Triassic and Jurassic continental red beds were thrusted over the Proterozoic-Early Paleozoic and Triassic clastic strata and Hercynian-Indosinian granitoids (Tang et al. 2006). From the Late Eocene to Oligocene, transtensional pull-apart basins were developed in this area, arranged in an echelon pattern (Bi et al. 2019).

The Pb-Zn-Ag polymetallic deposits are developed in the Changdu-Lanping basin (Fig. 5.8a) and fall into two genetic types: (1) Mississippi Valley-Type (MVT) deposits are closely related to the nappe structures, such as the super-large Jinding Pb-Zn deposit, Lanuoma, Zhaofayong, Sanshan, Changdong, Luoboshan (Song et al. 2017; Bi et al. 2019; Table 5.1; Fig. 5.8c); (2) sediment-hosted Cu-Ag deposits (e.g., Baiyangchang Cu-Ag deposit) are spatially associated with halokinetic structures and discordant breccia bodies interpreted as pre-evaporite grabens, which play an important role in controlling fluid flow in the basin and mineralization in reduced rocks, similar to the Proterozoic rock-hosted deposits in the Katangan Cu deposits (Leach and Song 2019). The above mineralization was mainly caused by the nappe and strike-slip faulting movements during the Himalayan orogeny.

5.8 Regional Metallogenetic Model

Under regional compression, substantial amount of fluid was discharged from the orogenic belts on both sides of the Changdu-Lanping basin (the Jinshajiang and Lancangjiang structure belt) and mixed with deep metamorphic and/or magmatic hydrothermal fluids. The ore-forming fluids may have entered the secondary faults in front of the nappes, forming vein-type and/or altered rock-type low-medium-temperature hydrothermal deposits (100–300°C; Li et al. 2010). Alteration types include silicic, argillite, carbonate and barite.

In addition, the strong intracontinental convergence and extrusion during Late Yanshanian-Himalayan period triggered the transition of the eastern margin of Changdu Basin, leading to partial melting of the lower crust and upper mantle, which formed the Yulong-Mangkang felsic (some alkalic) porphyry Cu-Au-(Mo) ore sub-belt (Fig. 5.8b).

5.9 Zaduo-Jinggu-Jinghong Cu-Sn Polymetallic Ore Belt (VI)

The belt is located between the Lancangjiang suture/fault zone and the Changdu-Lanping-Pu’er basin (Fig. 5.1). It is related to the late Early Paleozoic-Early Mesozoic Zaduo-Jinggu-Jinghong magmatic belt. This belt contains massive Cu polymetallic sulfide deposits, including the Dapingzhang, Sandashan and Minle VMS deposits.

5.9.1 Geological Evolution and Mineralization

The oldest exposed sequences are the Middle-Upper Silurian andesite, rhyolite and sedimentary rocks formed in back-arc-basins (Lehmann et al. 2013). The Carboniferous strata are mainly composed of clastic rocks and mafic volcanic rocks in the continental marginal zones. The Permian consists of island arc volcanic-sedimentary formation (clastic and carbonate rocks, basalt to rhyolite). The Middle-Lower Triassic comprises an arc volcanic-sedimentary suite, including (basaltic)-andesite-rhyolite and pyroclastic rocks. A set of K-rich bimodal volcanic suite (basalt and rhyolite) was formed in Yunxian-Wenyu-Minle area (northern part of the belt) during the Late Triassic (Mo et al. 1993). The Middle-Late Silurian-Late Triassic volcanic-sedimentary activities are most closely related to the Cu polymetallic mineralization (Li et al. 2010). The earliest magmatic intrusion occurred in Caledonian period. Zircon U-Pb and whole-rock Re-Os dating of dacite-rhyolite in the Dapingzhang copper deposit show that the rock- and ore-forming ages are uniformly ca. 420 Ma. The pluton intruded mainly into the Permian-Triassic island arc volcanic-sedimentary rocks, including mainly diorite, granodiorite, monzogranite and granite porphyry. The granitoids show I-type characteristics (Mo et al. 1993).

Mineralization is closely related to magmatism and can be divided into two types: (1) VMS deposits are related to Late Silurian-Early Carboniferous volcanic passive margin magmatism and Late Triassic post-collisional rift-related magmatism, such as large Dapingzhang and the medium Sandashan and Minle Cu polymetallic deposits (Table 5.1; Dai et al. 2004; Zhu et al. 2011; Lehmann et al. 2013); (2) Greisen-quartz vein-type Sn polymetallic deposits, which are closely related to the Indosinian island arc magmatism. These deposits may have been formed by the post-magmatic replacement-filling effect and are distributed in the southernmost part of the belt, such as the Bulangshan and Mengsong (Li et al. 2010).

5.9.2 Regional Metallogenetic Model

In the Late Caledonian, accompanying the expansion of the Southern Lancangjiang ocean basin, volcanic activities were developed in the volcanic passive margin on the western edge of the Lanping-Pu'er terrane (Jinggu-Jinghong area), forming the VMS-type deposits in the Late Silurian-Early Carboniferous submarine spilite-keratophyre series (Fig. 5.9a; Li et al. 2010).

Fig. 5.9

Regional metallogenic model for the Zaduo-Jinggu-Jinghong polymetallic metallogenic belt (Fig. b modified after Leach and Song 2019)

At the end of Early Permian, the Lancangjiang ocean began to subduct eastward beneath the Lanping-Pu’er terrane, and the passive margin of the Lanping-Pu’er terrane changed to be an active margin. In the Triassic, arc-arc collision and accretion occurred, forming the Permian-Triassic island arc calc-alkaline intermediate-felsic volcanic-sedimentary sequences, together with extensive Indosinian collisional-related granitoid emplacement. The ore-forming fluids accumulated in the late-stage intrusive activity may have interacted with the surrounding rocks to form post-magmatic hydrothermal quartz vein-type Sn-W polymetallic deposits, together with the ore-related skarnization, greisenization, silicification and carbonation. The ore-forming intrusions are generally monzogranite, granite porphyry and other volatile-rich granites (Fig. 5.9b).

In the early Late Triassic, the volcanic arc changed from extrusion to post-collisional extension, forming a rift basin along this belt. In the basin, the volcanism is dominantly bimodal and may have brought in large quantities of ore-forming materials. Meanwhile, the ore-forming materials interact with the materials in the seawater to form the hydrothermal mineralization system. Under relatively reducing conditions, VMS deposits occur in the bimodal assemblage of felsic volcanic rock series (Fig. 5.9c; Li et al. 2010).

5.10 Leiwuqi-Lincang-Menghai Sn-Fe-Pb–Zn Polymetallic Ore Belt (VII)

Located in the west of Lancangjiang fault/suture belt (Fig. 5.1), the main body of the Leiwuqi-Lincang-Menghai is a Sn-Fe-Pb-Zn polymetallic ore belt developed on the Leiwuqi-Dongdashan and Lincang-Menghai magmatic arcs. The ore belt can be divided into two sub-belts: the Leiwuqi-Zuogong Sn-W and Pb-Zn sub-belt in the north and the Lincang-Menghai Sn-Fe-Cu-rare metal sub-belt in the south.

5.10.1 Leiwuqi-Zuogong Sub-Belt

The main body of Leiwuqi-Zuogong is superimposed on the fold-thrust belt in the eastern margin of the Zuogong block and the Leiwuqi-Dongdashan magmatic arc. In addition to the small-/medium-sized Sn deposits related to granite, many Ag-Au-Cu mineral occurrences have been found in this sub-belt.

5.10.1.1 Geological Evolution and Mineralization

The Precambrian Jitang Group and the lower Paleozoic Youxi Group constitute the main body of the Taniantaweng terrane, which was in a passive continental margin setting during the Carboniferous-Permian. These strata are overlain by Middle-Upper Triassic fluvial-shallow marine carbonate-clastic rocks with minor volcanic inter-beds or locally overlain by Jurassic pelagic/terrestrial clastic-carbonate rocks. Magmatic rocks include metamorphosed mafic volcanic rocks of Precambrian Jitang Group and Lower Paleozoic Youxi Group, Carboniferous-Permian mafic volcanic rocks and Mesozoic-Cenozoic intermediate-felsic intrusive rocks. Among them, the Mesozoic-Cenozoic intermediate-felsic intrusive rocks are closely ore-related. Rock types of the granitoids include granodiorite, monzogranite, albite granite and granite porphyry. Strong structural deformation and tight folding resulted in nappe structures which are west-trending or south-trending in the southern section and north-trending in the northern section.

The ore metal assemblages are mainly Sn-W in Leiwuqi-Binda, Ag-Sn in Chaya-Jitang-Zuogong-Meiyu and Ag-Au in Tiantuo-Dongdacun. The main deposit types are Greisen-quartz vein-type W-Sn deposits formed by post-magmatic metasomatism (e.g., the Saibeinong, Xiayu and Duila Sn-(W) deposits; Table 5.1; Qiu et al. 2011) and hydrothermal vein-type Ag(-Au) deposits. The former is related to the late Yanshanian-Himalayan felsic granitoids, while the latter is mainly controlled by the Leiwuqi-Zuogong main fault and the NNW- and/or NNE-trend secondary faults. Furthermore, these two kinds of mineralization can coexist spatially.

5.10.1.2 Regional Metallogenetic Model

The Paleo-Tethys arc volcanic-sedimentary series provided material basis for the later tectono-magmatic mineralization in this sub-belt. On the geochemical background of host rocks in the Precambrian Jitang Group, Lower Paleozoic Youxi Group and Upper Triassic strata, the elements of W, Sn, Ag, B, As, Sb, Bi, Hg and Pb could be several to tens of times higher than the Clarke values. Therefore, these strata are related to Sn-W (and/or Au-Ag) mineralization, and these volcanic-sedimentary sequences are important source beds in this sub-belt (Li et al. 2010).

During the Late Yanshanian-Himalayan period, strong tectonic deformation occurred in the continent-continent collision stage, forming a series of NW-trending nappes, strike-slip shears and related NNW-trending faults. Magmatic activities are developed along the NW-trending main fault zone, forming many intermediate-felsic granitic stocks including granodiorite, two-mica granite, albite granite and granite porphyry. The late Yanshanian-Himalayan granites are characterized by Sn-W and Ag-Au metallogenetic specialization. This is probably because the magma of the granites is mainly derived from the remelting of the continental crust with high metal background values and absorbed metal elements (e.g., Sn, W, B, Ag, Au and/or their combinations) which are eventually enriched in the high-middle temperature hydrothermal fluid. Therefore, in the late Yanshanian-Himalayan intracontinental convergence-compression setting, strong nappe, strike-slip shear and other tectonic processes, as well as the contemporaneous magmatic intrusion activities, are the main factors of tectonic-magmatic mineralization, forming the composite metallogenetic zone in this sub-belt (Fig. 5.10)

Fig. 5.10

Regional metallogenic model for the Zaduo-Jinggu-Jinghong Cu-Sn polymetallic metallogenic belt

5.10.2 Lincang-Menghai Sub-Belt

It is mainly developed in the Lincang-Menghai magmatic arc, which is about 500 km long and 20–70 km wide (Fig. 5.1).

5.10.2.1 Geological Evolution and Mineralization

The Lincang-Menghai sub-belt mainly distributes migmatite, migmatitic gneiss, leptynite, schist, marble and other middle-deep metamorphic rocks of the Precambrian Lancang/Damenglong, Chongshan and Ximeng Groups. The protolith is a set of marine intermediate-basic volcanic rocks and sedimentary rocks. The Silurian-Carboniferous sequence is mainly composed of carbonate and clastic rocks, while the Permian-Triassic sequence is composed of intermediate-felsic volcanic and pyroclastic rocks formed in the active continental margin. The Precambrian intermediate-high-grade metamorphic rocks are important host rocks for Fe and Sn-(W) deposits in this sub-belt. Magmatic rocks include the aforementioned intermediate-felsic volcanic rocks formed in the Precambrian Groups, Permian-Triassic intermediate-mafic/felsic volcanic rocks and widespread granitoids. The Triassic granitoids mainly include the Lincang granitic batholith, extending up to 370 km long and 50 km wide (Wang et al. 2010). Furthermore, there are also Zhibenshan granite at Caojian, Yunlong County of Yunnan Province and many small Yanshanian stocks at Menghai. From Changning to Ximeng, a series of crust-remelted granites is exposed along the Lincang-Menghai fault, and its secondary faults occurred mainly in Indosinian, late Yanshanian and Himalayan, respectively.

The Indosinian granitoids are spatial-genetically closely related to Sn-(W) and Cu-(Pb-Zn) mineralization, while the late Yanshanian-Himalayan granites are spatial-genetically closely related to rare metal mineralization. There are mainly three types of ore deposits in this sub-belt: (1) post-magmatic hydrothermal Greisen-quartz vein-type Sn-(W) and Cu-(Pb-Zn) polymetallic deposits, which are mainly distributed in the Lincang granitic batholith and its surrounding rocks, such as Tiechang, Haobadi, Changdonghe Sn-W deposits (Liao et al. 2013); (2) modified VMS-type Fe deposits (e.g., the Huimin and Damenglong; Table 5.1; Shen et al. 2002; Xu and Yin 2010), which are mainly distributed in the middle-deep metamorphic rocks of the Precambrian Lancang and Damenglong Groups. During the ore-forming process, Fe deposits experienced multi-stage and strong superimposed transformation and finally formed the banded iron formation (BIF) deposits, which mainly inhibited the formation of Proterozoic VMS deposits; and (3) rare and rare earth element deposits were developed in the oxidized zone of the intrusions.

5.10.2.2 Regional Metallogenetic Model

The Damenglong and Lancang Groups were formed in the back-arc-basin in Rodinia convergence period. During the process, the Huimin Fe deposit and other Fe deposits/prospects were formed by direct exhalation deposition in volcanic rocks during the back-arc rift volcanism (Fig. 5.11a). The mineralization was controlled both by volcanic and sedimentary factors. Subsequently, the Early Paleozoic Caledonian regional metamorphism (incl. migmatization) and the Late Paleozoic island arc magmatism resulted in the formation of modified VMS-type Fe deposits in the Precambrian metamorphic rocks.

Fig. 5.11

Regional metallogenic model for the Leiwuqi-Zuogong Sn (W) and Ag (Au) polymetallic metallogenic sub-belt

During the Late Yanshanian-Himalayan, the collisional setting and strike-slip activities controlled the magmatic intrusions of crust-remelted-type muscovite/biotite/two-mica granites, which superimposed the early-formed (e.g., Paleozoic) intrusions. At the same time, the early ore deposits were superimposed and modified. Meanwhile, the intrusions were often accompanied by Sn-(W) mineralization. In the intrusions, the supergene alteration zone developed rare earth metals deposits, together with monazite, phosphyttrite deposits (Fig. 5.11b, c).

5.11 Changning-Menglian Pb–Zn-Ag Polymetallic Ore Belt (VIII)

This belt is developed on the (quasi-)oceanic ridge ophiolite belts and is located in the western part of the Lincang-Menghai magmatic arc. It extends N-S-trending from Changning to Menglian, with a length of about 270 km and width of 10–20 km (Fig. 5.1).

5.11.1 Geological Evolution and Mineralization

The Changning-Menglian suture zone, which contains the remnants of Proto- and Paleo-Tethys, experienced the expansion of Proto-Tethys Ocean in the Early Paleozoic, the subduction of Paleo-Tethys and the formation of island arc in the Early-Late Paleozoic. The main collision occurred in the Late Permian-Early Triassic, with late-collision orogeny and basin-mountain inversion in the Late Triassic (Li et al. 2010; Wang et al. 2018). According to the sedimentary records and magmatic activities, a large amount of magmatic age data have been reported: the zircon U-Pb age of Changning-Menglian ophiolite is 270–264 Ma (Jian et al. 2009a, b), the zircon U-Pb age of Ganlongtang plagioclase amphibolite is 331–349 Ma in Lincang, and the K-Ar isochron age from the gabbro in Tongchangjie ophiolite is 385 Ma (Zhang et al. 1985; Cong et al. 1993).

Previous studies have also documented the oceanic crust remnants in the Nantinghe area (454–439 Ma; Wang et al. 2013a, b), the oceanic type (O-type) high-Mg adakitic tonalite (about 468 Ma) in Niujinshan (Wang et al. 2016) and sodic cumulative plagioclase (471 Ma) in Mangnahe (Liu et al. 2017). Meanwhile, a number of retrograded eclogite outcrops (Li et al. 2017) were found in Kongjiao, Nakahe, Genhenhe and other places in the north of Mengku town and Shuangjiang (Yunnan Province) through 1:50000 regional geological survey. There are two types of protoliths of the retrograded eclogites: (1) E-MORB-like tholeiitic basalts and (2) OIB-like alkaline basalts (Sun et al. 2017). The formation ages of these protoliths are mainly 801 Ma, 429–463 Ma and 254 Ma (Li et al. 2017). These studies indicate that there are also Early Paleozoic ophiolites in the Changning-Menglian suture zone, in addition to the Late Paleozoic ophiolites. There are mainly two deposit types in this belt: (1) VMS type, such as the Laochang Pb-Zn-Ag deposit, the Tongchangjie and Jinla deposits; (2) porphyry Mo-(Cu) deposits related to the Himalayan tectonic-magmatic activities, such as the Mo-(Cu) ore bodies superimposed onto the existing Pb-Zn-Ag deposit in Laochang (Table 5.1).

5.11.2 Regional Metallogenetic Model

The regional mineralization is mainly related to the volcanism in the oceanic basin expansion stage in the Hercynian and the tectono-magmatism of the continental convergent in Late Yanshanian-Himalayan.

During the Hercynian Changning-Menglian oceanic basin expansion stage, the ore fluids formed in the course of submarine volcanism was directly exhaled and deposited in the volcanic-volcaniclastic rocks. The mineralization occurred related to the mafic volcanic eruption and produced the Cu, Pb, Zn and Ag polymetallic ore bodies with massive, stratiform and reticulate veins, which was corresponding to the main metallogenic stage of the deposits (Fig. 5.12a).

Fig. 5.12

Metallogenetic model for the Changning-Menglian polymetallic ore belt (a) and the Laochang deposit (b) (modified after Li et al. 2009)

During the intracontinental convergence stage of the Late Yanshanian-Himalayan period, extensional setting, structure-excavation and corresponding plutonism of metamorphic core complex in the Changning-Gengma fold-thrust belt were developed. The concealed porphyries may be related to the Mo-Cu mineralization, which are superimposed on the Hercynian VMS-type ore bodies. This process has modified and upgraded the ore bodies by various ways and controlled their shape and location, such as the Laochang Pb-Zn-Mo-Cu deposit (Fig. 5.12b).

5.12 Baoshan-Zhenkang Pb–Zn-Hg and Rare Metal Ore Belt (IX)

This belt is located in the west of Changning-Menglian ore belt, extending from Liuku and Baoshan in the north to Zhenkang in the south. This belt is about 230 km long and 50 km wide (Fig. 5.1).

5.12.1 Geological Evolution and Mineralization

In the Baoshan-Zhenkang block, a strong rifting process of the passive continental margin was developed from the late Precambrian to the early Paleozoic, and thick-bedded sub-flysch sequences were deposited in the Sinian-Cambrian. This region began to transform into a stable sedimentary setting, with the development of the littoral-neritic clastic rocks and impure carbonate rocks in the Ordovician. Subsequently, the sedimentation turned into calcareous sandy and argillaceous formation, which rapidly transitioned upward to impure carbonate inter-calated siliceous sedimentation during the Devonian-Carboniferous. In the early stage of the passive continental margin rift, a series of tectonic-magmatic events occurred in this region, as recorded by the Zhibenshan granite (Rb-Sr isochron age: 645 Ma) and the Pinghe granite (Rb-Sr isochron age: 529.9 Ma) (Zhang et al. 1990). The Paleozoic multi-layered carbonatites are important Pb-Zn-Ag polymetallic ore bodies. Then in the late Yanshanian-early Himalayan, the Pb-Zn-(Ag), Fe, Cu, Hg and Sb mineralization related to intermediate-felsic magmatism were superimposed on the Paleozoic ore bodies. In addition, the Late Cretaceous-Early Himalayan intermediate-felsic magmatism also formed rare earth metal (REM) deposits, such as the Huangliangou Bi-Ni-Nd deposit, and the Luziyuan, Hetaoping, Jinchanghe and Heiniuwa Pb-Zn polymetallic deposits (Table 5.1; Wang et al. 2014; Xu et al. 2019a).

5.12.2 Regional Metallogenetic Model

Regional mineralization is closely related to the evolution process of fold belt of Santaishan-Luxi on the west side and the Changning-Menglian suture zone on the east side. During the Paleozoic, the Baoshan-Zhenkang terrane was in a passive continental margin setting, with Proto-Tethys and Paleo-Tethys developed (Li et al. 1999). During the Early Paleozoic, in the sub-flysch formation which contained volcanic rock, siliceous and carbonate rocks in the passive continental marginal (rift) basin of the central-east Baoshan-Zhenkang terrane, the ore-forming materials were deposited in the Cambrian-Ordovician bioclastic/reef limestone and in the carbonate-clastic transition interface by means of the (bio)-chemical process. Furthermore, the Early Paleozoic evolution may also have provided metals for the later Pb-Zn-(Ag), Fe and Cu mineralization that are of sedimentary-modified, skarn and tectonic-hydrothermal deposits (Fig. 5.13a).

Fig. 5.13

Metallogenic model for the Baoshan-Zhenkang nonferrous and rare metals ore belt

Accompanying with the tectonic-magmatic hydrothermal activities, the infiltrated meteoric water or formation water was heated in the crust, which circulated in the sequence. The fluids leached and extracted the ore-forming materials and then formed ore fluids which migrated upward along the fault systems of the Baoshan-Zhenkang ore belt. When the ore fluids migrated to the inter-layer fracture zones in the Paleozoic strata, or the structural detachment spaces on the fold axis, or the contact interfaces between the carbonates and clastic rocks, the early-formed deposits were reworked and upgraded to form sedimentary-modified-type Pb-Zn-(Ag) polymetallic deposits. The hydrothermal vein-type Hg-Sb-As polymetallic deposits controlled by structures could also be formed in the new ore-host space (Fig. 5.13b).

During the Yanshanian-Himalayan period, the intermediate-felsic magmatism superimposed on the early-formed skarn Pb-Zn-(Ag) polymetallic deposits or resulted in stratiform Pb-Zn-Cu-Fe-(Ag) skarn mineralization, such as Luziyuan and Fangyangshan (Xu et al. 2021a, b). Some post-magmatic hydrothermal fluids rich in alkali, volatiles and rare metals produced the ore-bearing pegmatite veins by metasomatism-filling along the inner or outer-contact zones of intrusions and their surrounding rocks, and pegmatite-type rare metal deposits were developed (Fig. 5.13b).

5.12.3 Tengchong-Lianghe Sn-W and Rare Metals Ore Belt (X)

This belt is located in the southern part of the Bomi-Tengchong magmatic belt and extends northward to Chayu. The belt is connected to the Southeast Asian Sn belt in the south, forming a Sn belt of 2500 km long. Many Sn polymetallic deposits, including two large (Xiaolonghe and Lailishan) and several medium (e.g., Tieyaoshan, Laopingshan) ones, and one large rare metal deposit (Baihuanao) is distributed in this belt (Fig. 5.1; Li et al. 1999).

5.12.4 Geological Evolution and Mineralization

The metamorphic basement of the magmatic belt is composed of the Proterozoic Gaoligongshan Group. Late Carboniferous-Permian glaciofluvial deposits and Middle Triassic carbonate rocks are the main components of the sedimentary cover. The Proterozoic Gaoligongshan Group is composed of greenschist-amphibolite facies metamorphic volcanic-sedimentary sequence, showing strong migmatization and ductile shear deformation features. The Carboniferous Menghong Group is sandy slates inter-calated with calc-silicates, which are the main surrounding rocks of granites and Sn polymetallic deposits in the belt.

On the basis of regional metamorphism (including migmatization) in the Precambrian, Caledonian and Variscan, intensive granitic magmatism was developed from the Late Mesozoic to the early Cenozoic, forming the Sn ore belt in western Yunnan Province. The Sn polymetallic mineralization has close genetic-temporal-spatial relation with the Mesozoic and Cenozoic granites. Three nearly parallel, N-S-trending magmatic-metallogenetic sub-belts (i.e., Eastern, Central and Western) were recognized from east to west, with their ages gradually decreasing from east to west (Wang et al. 2013a; Chen et al. 2014, 2015). (1) The eastern sub-belt is distributed in the eastern Tengchong, containing Sn, Fe, Pb-Zn polymetallic deposits related to Late Jurassic-Early Cretaceous granitoids. The ore bodies are mainly developed in fractured zones of strongly altered surrounding rocks (skarns), such as Diantan, Dadongchang, Dakuangshan and Huiyao skarn deposits (Table 5.1; Dong et al. 2005; Deng et al. 2014; Tang, et al. 2018). (2) Central sub-belt is distributed between the Lianghe and Tengchong terranes and is dominated by Sn-W polymetallic deposits of Late Cretaceous granitoids. Ore-related alteration mainly includes greisenization (main ore-forming stage) and silicification. The Sn-W mineralization was superimposed on the early skarn-altered rocks. The ore bodies are distributed along the fractures of altered rocks, forming veins and stockworks and lenticular Sn-W ore bodies, such as the large Xiaolonghe Sn deposit and medium Tieyaoshan W-Sn deposit (Wang et al. 2013a; Chen et al. 2014, 2015). (3) Western sub-belt is located in the west of the Lianghe terrane and contains Early Paleogene granitic Sn-W and rare metals deposits, such as the large Lailishan Sn-W deposit and large Baihuanao rare metal deposit (Shen 2002).

5.12.5 Regional Metallogenetic Mechanism

The northward thrust of the Indian plate beneath the Eurasia during the Late Mesozoic-Early Cenozoic may have resulted in a large arc-shaped thrust belt in the Gongshan-Ruili region, accompanied by the formation of a mylonite belt with a width of hundreds of meters and a transition zone from ductile-brittle to brittle deformation along the Tengchong-Lianghe suture zone (Ma et al. 2021). This tectonic thermal event may trigger the partial remelting of lower crust (e.g., metamorphic basement) with geochemical anomaly of rare, nonferrous metals and volatiles. There are good geochemical barriers and ore-forming spaces in the structural superimposed and intersected space, which are conducive to the evolution of ore-forming fluids. Therefore, the ore-forming elements are eventually concentrated in the favorable structural traps (Fig. 5.14).

Fig. 5.14

Regional metallogenic model for the Tengchong-Lianghe Sn-W and rare metals metallogenic belt

The mineralization is spatially and temporally associated with the Mesozoic-Cenozoic granitoids in this ore belt, forming three nearly parallel, N-S-trending tectonic-magmatic ore sub-belts. Furthermore, the mineralization is mainly controlled by the metasomatic alteration and (along the fracture zone) post-magmatic hydrothermal fluids.