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The results are presented of petrographic, microthermometric and LRM analysis of fluid inclusions in garnet, diopside, quartz and calcite which show that the ore-forming fluids evolved from high temperature, high salinity and K-rich fluids through moderate- to high-temperature and CO2 (CH4)-rich fluids to moderate- to low-temperature and low-salinity fluids. The results suggest that the dominant volatile components were H2O, CO2 and CH4, with minor C2H6, H2S and N2., The results are presented of petrographic, microthermometric and LRM analysis of fluid inclusions in garnet, diopside, quartz and calcite which show that the ore-forming fluids evolved from high temperature, high salinity and K-rich fluids through moderate- to high-temperature and CO2 (CH4)-rich fluids to moderate- to low-temperature and low-salinity fluids. The results suggest that the dominant volatile components were H2O, CO2 and CH4, with minor C2H6, H2S and N2.

A new Ag-polymetallic mineralisation belt was discovered parallel to the Gangdese porphyry Cu belt on the northern side of the Gangdese Range. This WE-trending belt is controlled by the Pangduo-Cuoqin thrust system. Most of the deposits occur at the junctions between the E-W-striking thrust faults and the N-S-striking tension faults. In the western part of the belt to the west of Yangbajing rift the deposits are dominated by hydrothermal vein-like Ag-Pb-Zn mineralisation and in the eastern part by skarn-type Cu-Pb-Zn-Ag mineralisation. The Ag content of ores is higher in the western belt. The deposits resulted from a hydrothermal process in the late period of continental collisional orogenic activity or in the early stage of collision-extension., A new Ag-polymetallic mineralisation belt was discovered parallel to the Gangdese porphyry Cu belt on the northern side of the Gangdese Range. This WE-trending belt is controlled by the Pangduo-Cuoqin thrust system. Most of the deposits occur at the junctions between the E-W-striking thrust faults and the N-S-striking tension faults. In the western part of the belt to the west of Yangbajing rift the deposits are dominated by hydrothermal vein-like Ag-Pb-Zn mineralisation and in the eastern part by skarn-type Cu-Pb-Zn-Ag mineralisation. The Ag content of ores is higher in the western belt. The deposits resulted from a hydrothermal process in the late period of continental collisional orogenic activity or in the early stage of collision-extension.

The deposit is characterised by vertical variations and a two-layer ore texture. CaO, MgO, Fe2O3, FeO, Cu, Au, Zn, Ag and As contents and average delta 18O and delta 13C values increase progressively from the lower disseminated-veinlet mineralised rocks to the upper stratiform ore beds. The data show that the deposit is of submarine sedimentary exhalative origin., The deposit is characterised by vertical variations and a two-layer ore texture. CaO, MgO, Fe2O3, FeO, Cu, Au, Zn, Ag and As contents and average delta 18O and delta 13C values increase progressively from the lower disseminated-veinlet mineralised rocks to the upper stratiform ore beds. The data show that the deposit is of submarine sedimentary exhalative origin.

Available data indicate that there have been at least two stages of tectonic evolution since the Miocene in the Tibetan plateau, which is now tectonically in a post-collisional stage. Mineralisation during the post- collisional periods has produced a variety of significant mid-Miocene deposits including the porphyry Cu deposits and the associated skarn Ag- Pb-Zn deposits along the Gangdese batholiths, the epithermal Sb-Au deposits in southern Tibet, the hydrothermal vein-type and skarn-type Ag- Pb-Zn deposits to the north of the Gangdese porphyry Cu belt and modern Cs-Au deposits related to hot-spring activity in the Tibetan plateau., Available data indicate that there have been at least two stages of tectonic evolution since the Miocene in the Tibetan plateau, which is now tectonically in a post-collisional stage. Mineralisation during the post- collisional periods has produced a variety of significant mid-Miocene deposits including the porphyry Cu deposits and the associated skarn Ag- Pb-Zn deposits along the Gangdese batholiths, the epithermal Sb-Au deposits in southern Tibet, the hydrothermal vein-type and skarn-type Ag- Pb-Zn deposits to the north of the Gangdese porphyry Cu belt and modern Cs-Au deposits related to hot-spring activity in the Tibetan plateau.

The tectonic evolution of the Tibetan orogen is divided into syn- collisional, late-collisional and post-collisional periods. The orogeny during the late-collisional period was characterised by intra-continental subduction, crustal shortening, large-scale thrusting and strike-slip faulting systems which developed in the margins of the Tibetan plateau, and resulted in the development of potassic porphyry stocks and carbonatite-alkalic complexes in eastern Tibet and potassic-ultrapotassic volcanic rocks in northern Tibet. Four significant metallogenic events occurred in the eastern margin of the Tibetan plateau, porphyry Cu-Mo(- Au) mineralisation related to a large-scale strike-slip faults system, REE mineralisation associated with carbonatite-alkalic complexes which formed the Mianning-Dechang REE belt in western Sichuan, Pb-Zn-Ag mineralisation controlled by thrust faulting systems, forming at least two large Pb-Zn-Ag deposits in the Lanping strike-slip pull-apart basin, western Yunnan, and Au mineralisation related to large-scale shearing, which produced shear- or orogenic-type Au deposits in western Sichuan and Yunnan., The tectonic evolution of the Tibetan orogen is divided into syn- collisional, late-collisional and post-collisional periods. The orogeny during the late-collisional period was characterised by intra-continental subduction, crustal shortening, large-scale thrusting and strike-slip faulting systems which developed in the margins of the Tibetan plateau, and resulted in the development of potassic porphyry stocks and carbonatite-alkalic complexes in eastern Tibet and potassic-ultrapotassic volcanic rocks in northern Tibet. Four significant metallogenic events occurred in the eastern margin of the Tibetan plateau, porphyry Cu-Mo(- Au) mineralisation related to a large-scale strike-slip faults system, REE mineralisation associated with carbonatite-alkalic complexes which formed the Mianning-Dechang REE belt in western Sichuan, Pb-Zn-Ag mineralisation controlled by thrust faulting systems, forming at least two large Pb-Zn-Ag deposits in the Lanping strike-slip pull-apart basin, western Yunnan, and Au mineralisation related to large-scale shearing, which produced shear- or orogenic-type Au deposits in western Sichuan and Yunnan.

The main collisional event lasted about 25 Ma from 65 Ma to 41 Ma and resulted in the formation of the main part of the orogenic belt. At least four important ore-forming events occurred during the main collisional orogenic epoch, including the Sn and rare metal event related to crust- derived granite, forming the Tengchong Sn and rare metal ore concentration area in the east Tibetan plateau, the Cu-Au-Mo event related to crust/mantle-derived granite, forming a Cu-Au ore belt 100 km long in south Gangdese, the shear zone Au event, forming the potential Au belt along the Yarlung Zangbo suture zone, and the Cu-Au event related to crust uplift, forming porphyry/epithermal transitional type Cu-Au deposits represented by the Xiongcun deposit., The main collisional event lasted about 25 Ma from 65 Ma to 41 Ma and resulted in the formation of the main part of the orogenic belt. At least four important ore-forming events occurred during the main collisional orogenic epoch, including the Sn and rare metal event related to crust- derived granite, forming the Tengchong Sn and rare metal ore concentration area in the east Tibetan plateau, the Cu-Au-Mo event related to crust/mantle-derived granite, forming a Cu-Au ore belt 100 km long in south Gangdese, the shear zone Au event, forming the potential Au belt along the Yarlung Zangbo suture zone, and the Cu-Au event related to crust uplift, forming porphyry/epithermal transitional type Cu-Au deposits represented by the Xiongcun deposit.

The results of fluid inclusion analyses indicate that the ore-forming fluids of the deposit were dominated by meteoric water, with the probable participation of magmatic water. The highly saline fluids may have been related to the immiscibility of magmatic water, and were important media for base metals transport. The ore-forming fluids were characterised by high organic gas contents, which were an important factor in Cu and Au mineralisation. The deposit differs from typical high-sulphidation and low-sulphidation epithermal deposits formed in a stable, shallow, high- temperature regime. The reduction of SO2 by organic gas produced large quantities of HS- which was necessary for the precipitation of base metals and the transport of Au in the ore-forming process of this type of epithermal deposit., The results of fluid inclusion analyses indicate that the ore-forming fluids of the deposit were dominated by meteoric water, with the probable participation of magmatic water. The highly saline fluids may have been related to the immiscibility of magmatic water, and were important media for base metals transport. The ore-forming fluids were characterised by high organic gas contents, which were an important factor in Cu and Au mineralisation. The deposit differs from typical high-sulphidation and low-sulphidation epithermal deposits formed in a stable, shallow, high- temperature regime. The reduction of SO2 by organic gas produced large quantities of HS- which was necessary for the precipitation of base metals and the transport of Au in the ore-forming process of this type of epithermal deposit.

Major and trace element data show that SiO2, Au, As and Sb contents increase progressively while CaO and MgO contents decrease gradually from unaltered to intensely silicified and mineralised limestones. SiO2 contents decrease with the increase in CaO and CO2 in intensely carbonated limestones. REE contents and chrondrite-normalised patterns in altered and mineralised rocks are largely consistent with those of unaltered laminated limestone host rocks. Fluid inclusion data indicate that the ore-forming fluids were of the Cl-rich type and that quartz and calcite formed at temperatures of around 200-338 degrees C. The water content of the fluids was predominantly meteoric and the ore-forming materials mainly crustal with a small mantle component., Major and trace element data show that SiO2, Au, As and Sb contents increase progressively while CaO and MgO contents decrease gradually from unaltered to intensely silicified and mineralised limestones. SiO2 contents decrease with the increase in CaO and CO2 in intensely carbonated limestones. REE contents and chrondrite-normalised patterns in altered and mineralised rocks are largely consistent with those of unaltered laminated limestone host rocks. Fluid inclusion data indicate that the ore-forming fluids were of the Cl-rich type and that quartz and calcite formed at temperatures of around 200-338 degrees C. The water content of the fluids was predominantly meteoric and the ore-forming materials mainly crustal with a small mantle component.

Two types of Cu- and Au-bearing deposits occur in the area, Hercynian synsedimentary sedex-type massive sulphide deposits and Yanshanian magmatic deposits. The marked differences in the distribution of Cu and Au in the deposits may be due to a gold-repelling effect which was controlled by the temperature field in the superimposition-reformation process of the deposits. During the heating process, active Au migrated upwards and accumulated at lower temperatures while the relatively inert Cu was mostly immovable, leading to a spatial distribution in the deposits., Two types of Cu- and Au-bearing deposits occur in the area, Hercynian synsedimentary sedex-type massive sulphide deposits and Yanshanian magmatic deposits. The marked differences in the distribution of Cu and Au in the deposits may be due to a gold-repelling effect which was controlled by the temperature field in the superimposition-reformation process of the deposits. During the heating process, active Au migrated upwards and accumulated at lower temperatures while the relatively inert Cu was mostly immovable, leading to a spatial distribution in the deposits.

The skarn-type deposit is directly related to pyroxene-monzodiorite with pyroxene-diorite as the enclosing rock. The formation of the deposit may be divided into three ore-forming stages, skarn, quartz-sulphide and carbonate. The results of isotopic analysis and REE geochemistry studies show that the ore-forming solution was at the initial stage dominated by magmatic water. Meteoric water gradually entered the mineralising system and played an important role in the ore-forming processes in the later stages. The C and O isotopic compositions of calcites in the ores are different from those of the marble in the ore field and are similar to the C and O isotopic compositions of magmatism. Si and S isotopes are quite similar to those in magma or magmatic hydrothermal solutions., The skarn-type deposit is directly related to pyroxene-monzodiorite with pyroxene-diorite as the enclosing rock. The formation of the deposit may be divided into three ore-forming stages, skarn, quartz-sulphide and carbonate. The results of isotopic analysis and REE geochemistry studies show that the ore-forming solution was at the initial stage dominated by magmatic water. Meteoric water gradually entered the mineralising system and played an important role in the ore-forming processes in the later stages. The C and O isotopic compositions of calcites in the ores are different from those of the marble in the ore field and are similar to the C and O isotopic compositions of magmatism. Si and S isotopes are quite similar to those in magma or magmatic hydrothermal solutions.

Several high-grade deposits are concentrated in the Guojialing granodiorite, Cishan granite and Archaean Jiaodong Group rocks in SE Penglai County. A thermoelectric study showed the distribution of P-type pyrite in NE- and NNE-trending zones, with the high-grade gold deposits located at the intersections between the zones where the frequency of P-type pyrite is greater than 90% and the average value of its thermoelectrical coefficient greater than 250 microvolts/degree C, with less than 1.5 dispersion. These characteristics indicate that the deposits formed in confined zones of tensile faulting under conditions of relatively low temperature, high contents of As, Sb and Te in the ore-forming fluids and insignificant variation in fluid temperature and composition. The abundant gold was derived by the fluid from the Guojialing granodiorite and deposits were located close to the channel along which the fluids ascended., Several high-grade deposits are concentrated in the Guojialing granodiorite, Cishan granite and Archaean Jiaodong Group rocks in SE Penglai County. A thermoelectric study showed the distribution of P-type pyrite in NE- and NNE-trending zones, with the high-grade gold deposits located at the intersections between the zones where the frequency of P-type pyrite is greater than 90% and the average value of its thermoelectrical coefficient greater than 250 microvolts/degree C, with less than 1.5 dispersion. These characteristics indicate that the deposits formed in confined zones of tensile faulting under conditions of relatively low temperature, high contents of As, Sb and Te in the ore-forming fluids and insignificant variation in fluid temperature and composition. The abundant gold was derived by the fluid from the Guojialing granodiorite and deposits were located close to the channel along which the fluids ascended.

The orebodies are mostly hosted by ultrabasic rocks dominated by diopsidites. Electron microprobe analysis indicates that the deposit is characterised by enrichment of Pt and Pd in minerals such as chalcopyrite, galena, sphalerite and pyrite, and by the presence of millerite. The chondrite-normalised REE patterns in the main metallic minerals are generally consistent with those of the host ultrabasic rocks, while stable isotope studies show that C, S and most of the metallic elements were probably derived largely from the host rocks and that meteoric water may have predominated in the ore-forming hydrothermal fluids., The orebodies are mostly hosted by ultrabasic rocks dominated by diopsidites. Electron microprobe analysis indicates that the deposit is characterised by enrichment of Pt and Pd in minerals such as chalcopyrite, galena, sphalerite and pyrite, and by the presence of millerite. The chondrite-normalised REE patterns in the main metallic minerals are generally consistent with those of the host ultrabasic rocks, while stable isotope studies show that C, S and most of the metallic elements were probably derived largely from the host rocks and that meteoric water may have predominated in the ore-forming hydrothermal fluids.

The deposit formed by weathering of ore-forming material from primary Carlin-type mineralisation during the late Yanshanian period, accumulation of the material during the early Pliocene by karstification, eluviation and slope washing, and final concentration of gold in the middle-lower part of the red clay profile by lateritisation during the Pliocene. The profile can be divided into six zones: topsoil, slope-wash zone of clays and mudrock/siltstone gravels, travertine-fen zone of mainly black clays, eluvial zone of red clays, saprolite zone and bedrock. The saprolites comprise weathered karst-collapse breccias of altered rocks and Jurassic mudrocks and siltstones, while the bedrock consists of altered and mineralised rocks, Jurassic mudrocks and siltstones, and Permian dolomites., The deposit formed by weathering of ore-forming material from primary Carlin-type mineralisation during the late Yanshanian period, accumulation of the material during the early Pliocene by karstification, eluviation and slope washing, and final concentration of gold in the middle-lower part of the red clay profile by lateritisation during the Pliocene. The profile can be divided into six zones: topsoil, slope-wash zone of clays and mudrock/siltstone gravels, travertine-fen zone of mainly black clays, eluvial zone of red clays, saprolite zone and bedrock. The saprolites comprise weathered karst-collapse breccias of altered rocks and Jurassic mudrocks and siltstones, while the bedrock consists of altered and mineralised rocks, Jurassic mudrocks and siltstones, and Permian dolomites.

The deposit has a two-layer texture. The SiO2, Al2O3, TiO2, K2O and Na2O contents are higher in the lower altered and mineralised rocks and Fe2O3, FeO, CaO, MgO and SiO2 are richer in the upper stratiform and massive ore beds and ore-bearing rocks. The REE contents, relatively enriched in HRR, are lower in the upper stratiform and massive ore beds than in the lower channelway phase-altered and mineralised rocks. The average delta34 S, delta18 O and delta30 Si values decreased progressively and the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204 Pb values increased gradually from the lower stockwork mineralisation to the upper stratiform massive ore bed, following descending crystallisation of coarse-fine metacolloform-colloform pyrite., The deposit has a two-layer texture. The SiO2, Al2O3, TiO2, K2O and Na2O contents are higher in the lower altered and mineralised rocks and Fe2O3, FeO, CaO, MgO and SiO2 are richer in the upper stratiform and massive ore beds and ore-bearing rocks. The REE contents, relatively enriched in HRR, are lower in the upper stratiform and massive ore beds than in the lower channelway phase-altered and mineralised rocks. The average delta34 S, delta18 O and delta30 Si values decreased progressively and the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204 Pb values increased gradually from the lower stockwork mineralisation to the upper stratiform massive ore bed, following descending crystallisation of coarse-fine metacolloform-colloform pyrite.

The results are presented of sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon dating of pyroxene diorite from the Chaoshan Au deposit in the Tongling mineral district, Anhui Province. The data indicate the occurrence of intrusive activity at 142.9 +/- 1.1 Ma. New U-Pb ages were obtained for quartz diorite from Tongguanshan and for the Xinqiao Cu-S-Fe-Au deposit. The data indicate that mantle source magmatic underplating occurred in the early Cretaceous (133-143 Ma). This suggests that magmatism and the associated ore-forming process became active in this area from the time of the Yanshanian movement., The results are presented of sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon dating of pyroxene diorite from the Chaoshan Au deposit in the Tongling mineral district, Anhui Province. The data indicate the occurrence of intrusive activity at 142.9 +/- 1.1 Ma. New U-Pb ages were obtained for quartz diorite from Tongguanshan and for the Xinqiao Cu-S-Fe-Au deposit. The data indicate that mantle source magmatic underplating occurred in the early Cretaceous (133-143 Ma). This suggests that magmatism and the associated ore-forming process became active in this area from the time of the Yanshanian movement.

Magmatic-hydrothermal ore deposits in collisional orogens are new targets for modern mineral exploration. Geologic and geochemical data (especially zircon U-Pb dating and Lu-Hf isotope data) for Mesozoic-Cainozoic magmatic rocks and associated ore deposits are integrated in the Lhasa terrane, and provide the first example in a continental collision terrane of the application of zircon Hf isotope data to image the lithospheric architecture and its relationship with ore deposits. Three crustal blocks are identified within the Lhasa terrane by the Hf isotope mapping method. Mesozoic subduction-related porphyry Cu-Au deposits and Cainozoic collision-related Cu-Mo deposits are exclusively located in regions with high eHf(more than 5) juvenile crust. Cu enrichment during differentiation of high fO2 arc magmas is the key for the formation of Mesozoic subduction-related porphyry Cu-Au. By contrast, remelting of the lower crustal Cu sulphide-rich magmatic cumulates within the juvenile crust is interpreted to have played a key role in the formation of Cainozoic collision-related Cu-Mo deposits. Granite-related Pb-Zn deposits cluster in the oldest crustal regions or developed along the margin of the old crustal block bounded by lithospheric faults. The porphyry Mo deposits are localised along the reworked margins of the old crustal block. It is suggested that crustal reworking released Mo from the old crust to form porphyry Mo deposits, whereas leaching of Pb and Zn from the Palaeozoic carbonate cover strata by felsic intrusion-driven fluids is critical to the formation of Pb-Zn ore deposits. Skarn Fe-Cu ore deposits are typically localised along a lithospheric discontinuity, through which crust-derived felsic melt mixed with Cu-rich mantle-derived mafic magmas ascending upward., Magmatic-hydrothermal ore deposits in collisional orogens are new targets for modern mineral exploration. Geologic and geochemical data (especially zircon U-Pb dating and Lu-Hf isotope data) for Mesozoic-Cainozoic magmatic rocks and associated ore deposits are integrated in the Lhasa terrane, and provide the first example in a continental collision terrane of the application of zircon Hf isotope data to image the lithospheric architecture and its relationship with ore deposits. Three crustal blocks are identified within the Lhasa terrane by the Hf isotope mapping method. Mesozoic subduction-related porphyry Cu-Au deposits and Cainozoic collision-related Cu-Mo deposits are exclusively located in regions with high eHf(more than 5) juvenile crust. Cu enrichment during differentiation of high fO2 arc magmas is the key for the formation of Mesozoic subduction-related porphyry Cu-Au. By contrast, remelting of the lower crustal Cu sulphide-rich magmatic cumulates within the juvenile crust is interpreted to have played a key role in the formation of Cainozoic collision-related Cu-Mo deposits. Granite-related Pb-Zn deposits cluster in the oldest crustal regions or developed along the margin of the old crustal block bounded by lithospheric faults. The porphyry Mo deposits are localised along the reworked margins of the old crustal block. It is suggested that crustal reworking released Mo from the old crust to form porphyry Mo deposits, whereas leaching of Pb and Zn from the Palaeozoic carbonate cover strata by felsic intrusion-driven fluids is critical to the formation of Pb-Zn ore deposits. Skarn Fe-Cu ore deposits are typically localised along a lithospheric discontinuity, through which crust-derived felsic melt mixed with Cu-rich mantle-derived mafic magmas ascending upward.