The Jinchang deposit, Ailaoshan Belt, is a hydrothermal gold-nickel deposit in which nickel mineralization formed during Triassic accretionary orogeny and gold mineralization during Miocene collisional orogeny. Although the nickel and gold orebodies largely overlap in an ophiolite melange at the contacts between ultramafic and metasedimentary sequences, nickel and gold concentrations have only a weak correlation in orebodies intersected in drill cores. The hydrothermal nickel sulfide ores are mainly concentrated at ultramafic-metasedimentary rock contacts. Broad alteration zones surround the contacts, with proximal quartz + clinochlore + magnesite in both rocks through quartz + fuchsite to distal muscovite + quartz assemblages in metasedimentary rocks. An apatite U–Pb age of 235.8 ± 1.8 Ma and a pyrite Re-Os age of 254 ± 21 Ma from the nickel mineralization indicate that it formed before the closure of the Ailaoshan Ocean. The As- and S-rich fluids during oceanic subduction leached Ni from the ultramafic rocks in the ophiolite melange forming the hydrothermal nickel sulfide ores. Orogenic gold mineralization comprises auriferous veins that host gold, Au- and Ag-rich sulfosalt. The veins cut the sulfides associated with nickel mineralization. The auriferous fluids reacted with nickel ore-stage pyrite forming porous or sieve-textures and patchy zoning in BSE images with native gold in pores. Geological and paleomagnetic evidence indicates that Miocene gold mineralization occurred in highly deformed Devonian metasedimentary rocks after the Oligocene–Miocene Ailaoshan sinistral shearing ( 30 to 20 Ma). The auriferous fluids are most likely sourced from the metasomatized mantle lithosphere if Jinchang has a similar source to other orogenic gold deposits in the Ailaoshan Belt.

The Buzhu Au deposit in the Himalaya orogen, experiencing Cenozoic uplift of the Himalaya, provides a window to study the control of crustal deformation on Au mineralization. The Au mineralization is characterized by quartz veins controlled by an extensional fault system, comprising W- to WNW-trending shear zones/faults and superposed NNE- to N-trending normal faults. The vein system experienced three deformation stages, stages I and II occurred in shear zones, and stage III developed in normal faults. The deformation comprises hydraulic brecciation in stage I and crack-sealing processes during stage II shear deformation in the brittle-ductile transition, followed by matrix-supported breccias progressively crosscut by veins in newly-formed normal faults in stage III. Stages I and II contain invisible-Au-dominated sulfides, while native Au and pyrrhotite formed in stage III. Blocky quartz with oscillatory and sector zoning patterns implies fluid pressure build-up processes in stage I. Pyrite displays coupled Au-As variation, high Au contents (<19 ppm), and restricted delta S-34 values (-3.6 to-2.4%o), supporting that fluid-rock reaction was responsible for Au precipitation. Elongated quartz of stage II displays contrasting bright and dark cathodoluminescence bands with corresponding high and low Al-Li concentrations, indicating fluctuating fluid pressure. Pyrite shows a negative correlation between Au (<45 ppm) and delta S-34 values (5.4-1.7%o, from cores to rims), consistent with fluid oxidation associated with a fluid pressure drop. Minor late quartz in open spaces transected earlier quartz, implying the hydrothermal system dropped to near- hydrostatic conditions. The partial replacement textures of pyrite and arsenopyrite from stage III, with varied delta S-34 values (5.9-9.3%o), and the existence of micro-inclusions and visible Au along the contact, suggest a fluid- mediated dissolution-reprecipitation process. Thus, it is demonstrated that mineralization occurred as the hydrothermal system transitioned from the relatively ductile to brittle domain, with varying Au precipitation mechanisms. This study further summarizes the similarities of Au mineralizing systems in young collisional orogens worldwide, particularly with respect to relationships between structural-hydrothermal system and rapid uplift.

Investigation of Hg isotope ratios of gold-related sulfides and penecontemporaneous mafic dikes from four orogenic gold provinces on the margins of the North China Craton and Yangtze Craton identifies three orogenic gold deposit (OGD) groups from different tectonic regimes. Ore-related sulfides of group 1 OGDs and mafic dikes from the craton margin reworked via oceanic subduction mostly have positive Δ199Hg values. The group 2 OGDs and mafic dikes from the margin that witnessed complex oceanic and continental subductions have mixed positive to negative Δ199Hg values. The group 3 OGDs on the margin that experienced continental subduction have dominantly negative Δ199Hg values. These isotopic differences indicate subduction histories have a first-order control on the distinct sources for the OGDs. It indicates that OGDs were derived from fluids from the mantle lithosphere metasomatized by contrasting subduction components, not from metamorphic fluids as is widely accepted. Group 1 OGDs and dikes were sourced from metasomatized mantle, which inherited the positive Δ199Hg of both recycled marine sediments and seawater during oceanic subduction, whereas group 3 with negative Δ199Hg was derived from mantle lithosphere metasomatized by subduction of mainly continental components. This genetic model identifies regions with high-grade metamorphic rocks above metasomatized mantle lithosphere as promising new OGD exploration targets.

Tethyan Himalaya is a famous Cenozoic gold metallogenic province formed by continental collision in southern Tibet. However, gold deposits are distributed sporadically, and systematic comparison of alteration, fluid composition, and mineralization process between those deposits at different tectonic levels (like mesozonal and epizonal ones) are absent. In this study, detailed comparisons between the hydrothermal alteration, sulfide textures, in-situ trace elements, and sulfur isotope compositions of the Mingsai Au deposit with the Mazhala Au-Sb deposit in the eastern part of Tethyan Himalaya to probe the mineralization process, ore-forming fluid composition, and controls on the genesis. Both deposits occur in Jurassic slate and tuff interlayer. Among them, the weakly altered slates comprise disseminated pyrite-ankerite-sericite-quartz along the bedding, while the tuff interlays are characterized by intense alterations of replacing feldspar, biotite, and other minerals with ankerite-chlorite-sericite and developing a large amount of euhedral to subhedral pyrite and arsenopyrite. Slate-host pyrites (Py-sa in Mingsai and Py-sb in Mazhala) with a homogeneous texture have low contents of Au (averaged at 0.33x10(-6)) and other trace elements, and a broad range of delta S-34 value (Py-sa: 8.12 parts per thousand similar to 15.6 parts per thousand; Py-sb: -24.3 parts per thousand similar to 3.36 parts per thousand), which is consistent with the delta S-34 value of regional Jurassic strata. Meanwhile, pyrites within the tuff interlayer of the Mingsai deposit (Py-va) have a concentric ring texture with highest Au (averaged at 14.3x10(-6)) and As, while pyrites within the tuff interlayer of the Mazhala deposit (Py-vb) have an irregular core-rim texture and high contents of Au (averaged at 3.8x10(-6)), Cu, Pb, and Sb. The tuff-host pyrites have similar delta S-34 values with the arsenopyrites (averaged at 2.7 parts per thousand of Py-va and 2.4 parts per thousand of arsenopyrite in Mingsai; 3.2 parts per thousand both for Py-vb and arsenopyrite in Mazhala), which is comparable with the delta S-34 value of pyrite in other orogenic gold deposits in southern Tibet. The significant variance of sulfur isotope composition in the slate-host barren pyrites, in the two deposits mentioned above, may be the result of ore-fluids reacting with the wall-rock that contains different sedimentary pyrite. However, the tuff-host auriferous pyrites have similar delta S-34 values with arsenopyrites can be attributed to the homogeneous fluid-rock interaction of congenetic fluids and the same surrounding rocks. As a preliminary conclusion, this research proposed that widespread tuff interlayers could be the preferential lithology for orogenic gold mineralization in southern Tibet. Orogenic gold deposits at different tectonic levels have an analogous source. The diversity of the mineralization system is controlled by different fluid-rock interaction processes.

The formation of high-grade gold ore has always been attractive, mostly located in Precambrian gold deposits with various mechanisms. Yet, in the orogenic Bangbu gold deposit, Tibet, we discovered that the coupled dissolution-reprecipitation (CDR) process and low melting point chalcophile elements (LMCE)-related melting are responsible for the formation of high-grade ore at ca. 38 Ma constrained by in-situ U-Th-Pb dating of hy-drothermal monazite. Three generations of pyrite have been recognized, metamorphic barren pyrite (Py I) in the host schist, hydrothermal pyrite (Py II) in the preceding primary laminated ore with an Au grade of similar to 8 g/t, and the hydrothermal coarse pyrite (Py III) in later massive ore with a grade of up to 29 g/t. In the primary laminated ore, the Py II in the sulfide ribbons is intergrown with native gold and colloform quartz and carries abundant trace element contents, such as Au, As, Cu, Pb, Zn, Te, Se, and Bi. These suggest that the rapid precipitation and local supersaturation occurred during the episodic crack-seal process. In the later high-grade massive ore, Py III exhibits distinct zonation, ranging from Py III-1 in the core to Py III-3 in the rim. The Py III-1, porous and rich in inclusions, has sharp boundaries and successive lattice orientation with the mantle Py III-2 suggesting a CDR process. Higher Au and As in Py III-2 than the Py III-1, and the close affinity between visible gold and LMCE melt inclusions at the boundary suggest that gold was remobilized and facilitated by the LMCE during the CDR process. The electron backscatter diffraction (EBSD) mapping result shows little crystallographic misorientations of Py III, excluding the deformation process that has significantly contributed to the remobilization of gold. The decrease of the delta S-34 ratio of pyrite between Py II (delta S-34 = 2.0%0 to 4.3%0, mean 3.4%0) and Py III (delta S-34 = - 2.5%0 to 3.8%0, mean-0.2%0) most likely reveals a more oxidized condition in the open space which may trigger the CDR process and gold remobilization of the pyrite in the primary ore. Within the zonation of Py III, an increasing trend of the 834S ratio represent the evolution of the redox state of fluids towards relatively reducing conditions during the healing of quartz veins. The newly obtained ca. 38 Ma age is comparable to regional amphibolite-to granulite-facies metamorphism during the continental subduction, which was considered to trigger the modifi-cation of primary gold orebody to form high-grade ore.

The controls of fluid redox states on disseminated gold mineralization remain ambiguous. To address this, this study compared the hydrothermal alteration and auriferous pyrite geochemistry in lamprophyres, Zhenyuan gold deposit, which were infiltrated by fluids with varied redox states. Vein-A, vein-B, and vein-C were distinguished and they contain different sulfur-bearing minerals, i.e. pyrite, pyrite and barite, and barite, respectively. This suggests the gradual oxidzing formation conditions from vein-A to vein-C. Alteration halos enveloping vein-A and vein-B develop disseminated pyrite. In the vein-A halos, alteration minerals transit from pyrite to Fe-carbonates outwards, which was well replicated by the thermodynamic simulation of the successive reaction of H2OCO2-H2S-Au-bearing fluid with lamprophyres. The precipitation of pyrite grains in vein-B halos is farther from vein-B, suggesting progressive fluid-rock interaction (FRI) first induced the reduction of oxidized S followed by the pyrite precipitation. Additionally, & delta;34S values of pyrite are more scattered in vein-B halos (-8.0 to 4.7 & PTSTHOUSND;) than in vein-B, vein-A, and vein-A halos, implying the sulfate-sulfide disequilibrium. Pyrite in vein-B halos displays higher As concentrations than that in vein-A halos due to the strong redox dependence of As partition from fluids to pyrite. Au and Au/As of halo-hosted pyrite grains decrease outwards, and pyrite in vein-B halos has low Au and Au/As (below 93.93 ppm and 0.005, respectively) compared to that in vein-A halos (below 1597.08 ppm and 0.031, respectively). It is thus suggested that Au concentrations in ore fluids decreased during outwards FRI, and the lack of pyrite grains in proximal alteration zones results in lower gold concentration in pyrite under relatively oxidized conditions. This study reveals that the fluid redox conditions can affect As concentrations and spatial distribution of pyrite in alteration halos, which directly controls invisible gold precipitation.

Hydrothermal alteration and mineralization types of orogenic gold deposits display many variations depending on formation depths, types of host rock, compositions of ore fluids, spatial positions, fluid/rock ratios, and repetitive modifications during multiple fluid infiltrations in the complicated processes of fluid-rock interaction. Therefore, establishing holistic reference patterns of hydrothermal alteration with associated mineralization for the orogenic gold system is necessary. Based on the observation of typical orogenic gold deposits and thermodynamic simulation of fluid-rock reaction, the general features of proposed patterns include: (1) Orogenic ore fluids are capable of transporting sufficient gold from deep (5 kbar and 600 degrees C) to shallow (1 kbar and 200 degrees C) crustal levels, resulting in alteration and mineralization occurred in a much-varied depth. Only considering the effects of fluid-rock reaction and sulfidation, the formation of pyrrhotite and pyrite at relatively high and low P-T conditions, respectively, is the most important mechanism driving gold precipitation. In addition, the changes of fluid fO(2) and pH can also trigger a decrease in the gold solubility in fluids. (2) Multiple waves of fluid infiltration are capable of dissolving the early-formedulfides and gold, and reprecipitate them in the distal alteration zones, which can explain the irregular gold concentration distribution patterns in wide alteration zones. The fluids under higher P-T conditions (5 kbar and 600 degrees C and 3 kbar and 400 degrees C) are more capable of dissolving early-formed sulfides and gold. Additionally, the later infiltrated fluids can transform early-formed pyrrhotite into pyrite. (3) The model of interactions between ore fluids and aluminosilicate rocks at varied P-T conditions indicates that the alteration mineral assemblages in hypozonal deposits (>12 km) mainly include biotite, amphibole, anorthite, K-feldspar, quartz, and pyrrhotite assemblages; that those in mesozonal deposits (6 to 12 km) are characterized by chlorite, calcite, quartz, muscovite, pyrite or pyrrhotite. The epizonal deposits (<6 km) commonly develop more abundant Fe-Mg bearing carbonates (e.g., dolomite, ankerite, and siderite), quartz, muscovite, and pyrite. The compositional variations of ore fluids and host rocks have important controls on the development of iron-oxides and carbonaceous material. (4) The alteration halo is relatively restricted under hypozonal to lower mesozonal conditions. However, broad carbonation develops under upper mesozonal to epizonal conditions, with Fe-Mg bearing carbonates and calcite distributed in proximal and distal zones, respectively.

The extreme fluctuations in pressure during earthquakes are widely regarded as responsible for gold mineralization in quartz-vein-hosted gold deposits. However, it is barely noticed that base metal sulfides can precipitate together with gold during these processes. Here we present the phenomenon and unravel the mechanism of the co-precipitation of Au and base metal sulfides during the fluid boiling via geological study and thermodynamic modeling, respectively. The Bangbu deposit, a lode-type orogenic gold deposit in Tibet shows two mineralization substages of pyrite. The pyrite formed in the later substage is hosted in the wall rock selvages of laminated crack-seal quartz veins formed by the fault-valve processes. The pyrite grains are characterized by anhedral small crystals with porous textures and abundant native gold, chalcopyrite, galena, and sphalerite inclusions. They also contain higher concentrations of Cu, Pb, Ag, Sb, and Au, and lower concentrations of Co and Ni, compared to the euhedral large-grained pyrite formed in the initial substage. The textural and trace element characteristics of the pyrite indicate that vigorous boiling occurred during fault-valve behavior, which decreased the solubilities of Au, Cu, Pb, and Zn in the ore fluid in Bangbu. The co-precipitation of Au and base metal sulfides triggered by fluid boiling has also been reported in other orogenic gold deposits worldwide. Thermodynamic models are designed to acquire the predominant species and solubility of Au, Cu, Pb, and Zn in orogenic ore fluids under varied chemical conditions. The results show that Au, Cu, Pb, and Zn are dominantly transported as hydrosulfide complexes under lower mesozonal to epizonal deposit conditions. At temperatures of about above 350 ?, Au hydrosulfide species still predominates, but the predominant Cu, Pb, and Zn species change from hydrosulfide to chloride complexes. A sudden decrease in the reduced sulfur concentration during fluid boiling may be the most important mechanism controlling the precipitation of Au, Cu, Pb, and Zn in lower mesozonal to epizonal deposits. The decrease of logfS2 during fluid boiling can increase the fluid pH, resulting in the decrease of solubilities of base metal chloride complexes and thus explain the co-precipitation of Au and base metal sulfides in hypozonal deposits.

Although the term orogenic gold has become widely accepted over the past 20 years for disseminated-to lode style gold deposits that formed in a variety of tectonic environments within convergent margins, models for orogenic gold systems have remained controversial. The main debates include interpretation of stable isotope and fluid inclusion data that are particularly equivocal for orogenic gold systems, the nature of lithospheric control on the generation of orogenic gold belts, and more critically, the role of deep crustal regional metamorphism or alternatively metasomatized and fertilized mantle lithosphere as sources of ore metals and fluids.& nbsp;The giant to world-class orogenic gold systems of China, now the premier gold producer globally, are in gold provinces or belts of several ages that are mostly marginal to Precambrian cratons or blocks, including the North China Craton and South China Block, an amalgamation of the Yangtze Craton and Cathaysia Block. Deposits from these gold provinces provide crucial evidence to constrain genetic debates. Importantly, following the acceptance that the giant Jiaodong gold province formed over 1700 million years after regional metamorphism in the host terrane, an increasing number of deposits, including the Phanerozoic hypozonal deposit at Danba, are shown to have postdated regional metamorphism and formed from components that were not derived from the host crustal rock sequences. A subcrustal model involving devolatilization of fertilized mantle lithosphere, that was metasomatized via earlier subduction processes involving oceanic sediments and/or altered oceanic crust, is compatible with a variety of data. This includes Ar-40/Ar-36 vs. He-3/He-4 mantle-like plots for gold-related pyrite, sulfur isotope compositions of ore-related sulfides that are incompatible with a crustal source, and PGE distribution patterns of spatially related mafic dykes that implicate elevated sulfide contents of underlying mantle lithosphere. Chinese orogenic gold deposits formed in a variety of tectonic regimes from syn-subduction slab rollback, post-subduction slab breakoff, and lithosphere thinning along craton margins, to continent collision. In all cases, lithosphere-scale shear zones and faults were the conduits for ore fluids and metals derived episodically from devolatilization of a subducted slab and/or long-lived metasomatized and fertilized mantle. These fluids deposited gold mineralization in rock sequences adjacent to subsidiary shear zones and faults from crustal depths of > 20 km to < 5 km, with hydraulic fracturing and fluid phase separation potentially the most important depositional process for lode deposits and fluid-rock reaction dominant in disseminated deposits. As the H2O-CO2 ore fluid containing H2S infiltrated into structural-lithological traps, it reacted with the wall rocks under P-T conditions related to depth of gold deposition to produce a continuum of broadly depth-related alteration mineral assemblages.& nbsp;The characteristics of the widespread orogenic gold systems of China strongly implicate a sub-crustal fluid and metal source for orogenic gold in a variety of gold provinces. Based on deposits from outside of China, where gold provinces are more distal to Precambrian cratons, this source is most likely from the devolatilization of down-going subduction zones and sediment wedges in addition to devolatilization of previously fertilized mantle lithosphere as implied by the Chinese examples.

Since the Mississippi Valley-type (MVT) Pb-Zn deposit is one of the most important types of Pb-Zn deposit, and precise dating on mineralization age has always been the research focus on this type of ore deposit. The Youjiang Basin is an important MVT Pb-Zn metallogenic province in southwestern China. We apply LA-ICP-MS trace element mapping analysis and Re-Os isotope dating on ore pyrite from the Beishan Pb-Zn deposit in the eastern Youjiang Basin to probe the feasibility of high-precision dating. Eight pyrite samples yielded an isochron age of 443. 2 +/- 3. 3Ma with an extraordinary high MSWD of 320, which is obviously older than the host rock of Devonian carbonates. Thus, this age can not represent the mineralization time of the deposit. Two pyrite samples show relatively high Re contents of 107. 1 x 10(-9) and 260. 0 x 10(-9). LA-ICP-MS mapping on these two samples showed significant high Re signals of organic matter along the fractures of pyrite, which should contribute as a most predominant factor to the failure of Re-Os dating. In addition, model ages of the two high Re samples are 399. 0Ma and 402. 0Ma, which are broadly consistent with the time of ore-hosting Devonian strata. It is speculated that high Re matter may be sourced from host rocks. This study showed that the complicated microscopic ore textures and the resultant impurities of the samples are the most important unneglectable barriers for the high-precision dating of MVT ore deposit.

The Debao deposit, with stratiform orebodies in Middle-Upper Cambrian carbonate rocks, is a rare Early Paleozoic skarn copper deposit in the South China Block. Garnet U-Pb dating yielded a lower intercept 206Pb/238U date of 438.8 ? 7.3 Ma, which is coeval with the related granite (439 _ 441 Ma). Skarns contain garnets with andraditic compositions (Ad53_93Gr4_46Py1_8) and clinopyroxene (Hd5_11Di89_94Jo0_1 and Hd52_85Di13_46Jo1_4) with low Mn/Fe ratios (<0.1), showing typical mineral compositions of Cu skarn deposits. The proximal garnet skarn mainly developed at the bottom and both sides of the orebody, while distal pyroxene skarn developed in its interior and upper parts. The garnets in the bottom of the orebodies contain more andraditic compositions than their upper parts. The prograde skarn minerals have a range of ?18Ofluid values from 8.81 to 9.53?, and the sulfide minerals of the main ore stage have a range of ?34S values from -2.40 to 2.57?, both suggesting a magmatic origin of the ores. In the Debao deposit, hydrothermal magnetite from different skarn zones contains substantial amounts of Al, Sn, Ga, Mn, Mg, Ti, Zn, Co, V, and Ni. The content of Al and Ti in the magnetite, which was considered to derive from the wall rock due to fluid-rock interaction, was positively correlated with temperature. Magnetite in the retrograde skarn stage from the proximal garnet skarn zone contains more Ti and V than that from the distal pyroxene skarn zone, indicating a gradual decrease in temperature and increase in oxygen fugacity of the ore-forming fluid in this stage. The magnetite has higher Sn content (mainly hundreds to thousands of ppm) than normal skarn deposits, implying that high oxygen fugacity occurs during the retrograde skarn stage. Subsequently, the formation of magnetite led to a decrease in the oxygen fugacity of the ore-forming fluid. The decrease of oxygen fugacity and temperature provided favorable conditions for subsequent precipitation of Cu sulfides. Minor vein-type Cu mineralization related to late magmatic fluid extraction of sulfur from the sedimentary strata was recognized. All geologic and geochemical data suggested that the deep skarn in the region transformed from Early Paleozoic carbonate has copper mineralization potential.

The orogenic gold deposits formed in the oceanic subduction processes have attracted much attention, yet those generated in the following continental collision stages have been less researched. Tibet Plateau is the youngest continental collision product which has provide a rare opportunity to study the genesis of orogenic gold systems formed in the complete course from the oceanic subduction to continental collision. Three orogenic gold belts were delineated in Tibet Plateau : (1) the mesozonal quartz vein type deposits formed in 60 -43Ma along the Yalung Tsangpo suture zone under a compressional regime; (2) the mesozonal gold deposits, consisting of both quartz vein and disseminated ores, developed along shear zones in the oblique continental collision zone from the initiation to termination of crustal shearing during 32 - 21Ma; and (3) the widely distributed mesozonal to epizonal disseminated and veinlet gold deposits produced in Himalayan doming belt within 19 - 15Ma in the background of Miocene rollback of Indian continental lithosphere, and these deposits are commonly related to antimony mineralization. The features of mineralization and alteration, together with oreforming fluids physiochemical parameters, consistently indicate systematic and gradual shallowing of metallogenic depth of these three gold belts. The Cenozoic orogenic gold deposits in Tibet were formed during peak to retrograde metamorphism of regional crustal rocks. The mutiperiodic mineralization was mostly synchronized with multi-stage drops of convergence rate between India and Eurasia plates, and significantly controlled by oceanic slab breakoff and continental slab rollback. Ore fluids migration and spatial location of orogenic gold deposits were much determined by lithospheric structure. Ore fluids migrating upwards were considered to be driven by higher pressure of thicker lithosphere into the thinner lithosphere with less pressure. Metal precipitation of mesozonal quartz vein type gold deposits was controlled by repetitive cracking-sealing processes and related fluid immiscibility, by contrast, the mesozonal to epizonal disseminated gold deposits by fluid-rock reaction. The median of ams values of pyrites in the three belts are mostly near 0, irrelevant to the different hosting strata. The 8 18 0 values of ore fluids are compatible with the fluids derived from enriched mantle. The 4 degrees Ar/ 36 Ar and 3 He/ 4 He features of ore-related pyrites show clear mantle signatures. Moreover, the platinum-group elements of ore-related sulfides show distinct compositions from those of sulfides precipitated from magmatic hydrothermal. Geochemical features, in combination of mineralization postdating prograde metamorphism and synchronizing with the disturbance of mantle, implies that the ore fluids and metal of the three orogenic gold belts mainly sourced from subcrustal level. This paper further provided possible explanation for the temporal and spatial variation of hydrogen and oxygen isotope of ore fluids. The decrease of 811) values in the younger gold deposits in PaleoceneEocene gold belt is implicative for the input of supercritical fluids. The increase of fluid 8 18 0 values from Paleocene-Eocene to Miocene gold belts could be related to the transition of mantle metasomatic agent from earlier oceanic sediments to later continental components. In terms of the dominantly subcrustal source of ore fluids and the generally shallow metallogenic depth, it is proposed that the orogenic gold deposits in Tibet own great prospect potential.