Abstract:Abstract：Triassic tectonic evolution in China is characterized by high intensity and wide influence. However, the metallogenic study related to the major Triassic tectonic events has obviously been lagging behind. This paper preliminarily and systematically discusses the space-time distribution and basic characteristics of the large scale Triassic mineralization in China based on the latest research achievements. Triassic deposits in China are distributed mainly in the two main Triassic orogenic belts of the Kunlun-Qinling orogenic belt and the Red River - Ailaoshan orogen belt and their adjacent regions; Besides, there are a series of polymetallic deposits developed in the three intraplates of southern China, northeastern China and Xinjiang area. Major types of Triassic deposits mainly include： ① Cu-Ni sulfide deposits related to basic-ultrabasic rock; ② porphyry Cu-Au, Cu-Mo, Mo deposits, skarn Cu-Pb-Zn, Cu-Fe, Sn, W deposits and vein-type Au deposits related to intermediate-acid rocks and acidic plutons; ③ pegmatite-type rare metal deposits related to high temperature gas-fluids; ④ orogenic Au deposits related to tectonic-hydrothermal activities in the orogenic process; ⑤ MVT Pb-Zn deposits related to basinal fluids in the orogenic process; ⑥ carbonated vein-type Mo deposits related to mantle fluids. Most of the Triassic deposits in the Kunlun-Qinling orogen belt were mainly formed in collisional stage, or in the post-collision setting. In East Qinling area, the Triassic deposits are dominated by Mo, Au, with the formation ages mainly concentrated in 233-221Ma. In contrast, Au deposits and Pb-Zn deposits of Triassic are widely distributed in West Qinling area, Au deposits are distributed along the NW-trending brittle-ductile shear zones, and Pb-Zn deposits are largely concentrated in the two targe basins of Xicheng and Fengtai, whose metallogenic epochs are mainly in the Late Triassic (232-214Ma). In East Kunlun area, newly discovered Cu-Mo-Fe polymetallic deposits were formed in 240-210 Ma. Influenced by Neo-Tethys evolution, Triassic metal mineral resources are scattered in the Red River - Ailaoshan orogen belt, mainly distributed in Zhongdian ancient island arc, Yunnan-Guizhou-Sichuan border area in the east of the orogenic belt and Dulong area of southeast Yunnan. In Zhongdian area, the metallogenic ages are concentrated in 228-201Ma and their distribution shows the characteristics of porphyry-skarn Cu deposits in the middle part and porphyry-epithermal Cu-Pb-Zn deposits and Au deposits on both north and south sides. The dating results obtained in recent years indicate that Pb-Zn deposits in Yunnan-Guizhou-Sichuan border area were mainly formed in Triassic. Moreover, a series of Triassic W-Sn deposits have been discovered recently in Dulong area of southeast Yunnan, whose peak age is 214-209Ma. In addition to the two main collision belts, rare metal and W-Sn deposits in South China, rare metal and Mo deposits in Xinjiang, porphyry Mo deposits, Cu-Ni sulfide deposits and vein type Au deposits in Northeast China and its adjacent areas were also formed in Triassic, and all of these deposits were closely related to the collision regime, most Triassic deposits in South China were related to EW-extending tectonic-magmatic systems and derived from the emplacement of aluminum granite resulting from the remelting of thickened crust. The mineralization of Triassic deposits in Northeast China and its adjacent areas, Xinjiang, and some neighboring areas of Mongolia and Russian Altay as well as Siberia were probably related to mantle plume activities.

Abstract:Abstract：The Lianhuashan Cu-Ag deposit of Inner Mongolia is an important deposit in southern Da Hinggan Mountains metallogenic belt, and its mineralization is closely related to the plagioclase granite porphyry. Zircon LA-MC-ICP-MS dating of the plagioclase granite porphyry shows that its formation ages range from 236.8±0.77Ma (MSWD=0.85) to 237.9±0.71Ma (MSWD=1.02), suggesting that it is a product of the Triassic magmatism rather than the Middle Jurassic magmatic activity. The Lianhuashan plagioclase granite porphyry has εHf(t) values range from +5.6 to +11.5 with relatively high 176Hf/177Hf values and younger two-stage model ages (477~810Ma), indicating that it was mainly derived from the partial melting of the new-born lower crust that originated from the depleted mantle, and that there probably existed an important crustal growth event in Hinggan massif which occurred in the early Paleozoic-late Proterozoic period. Based on a systematical study of ~1100 zircon Hf isotope data from the magmatic rocks in the Xingmeng orogenic belt, the authors found that the Hinggan, Songnen and Jiamusi massifs have similar properties, and these three massifs, the Ergun massif and the North China plate margin have their respective crustal accretion histories, revealing that they had different early crustal evolution processes.

Abstract:Abstract：The Aoergai copper deposit is located in Xingfuzhilusumu area of Bairin Right Banner in Inner Mongolia, and its tectonic setting is Late Paleozoic accretion orogenic belt of southern Da Hinggan Mountains. The samples collected in this study were intermediate-acid intrusive rocks. Zircon SHRIMP U-Pb dating results show that the granodiorites were formed at 245.4±1.8 Ma （MSWD=1.4）, being the product of magmatism in early Indosinian period. The granodiorites in the Aoergai copper deposit have similar petrogeochemistral characteristics to adakite. The granodiorites yielded the following data: SiO2≥56 wt.%（65.03~70.11 wt.%），Al2O3≥15 wt.%（14.45~15.49 wt.%），MgO＜3 wt.%（1.18~1.61 wt.%），Y＜18μg/g（5.85~6.83μg/g），Yb≤1.9 μg/g（0.416~0.637μg/g），Sr＞400μg/g（380~642 ug/g）, LREE/HREE=11.60~12.24，and δEu=1.00~1.18, indicating that they were formed at a great depth and under strong stress. The granodiorites have high εNd (t) values（+3.9~+4.4）, low (87Sr/86Sr)i values（0.70380~0.70412）, and young Nd model ages (578~657Ma)，suggesting that the magma might have been derived from a depleted mantle source in Neoproterozoic. Based on regional tectonic settings, the authors consider that the granodiorites in the Aoergai copper deposit were most likely derived from partial melting of mafic materials in the depleted mantle in a compression tectonic setting after the disappearance of the Paleo-Asian Ocean. Based on regional analysis, the authors suggest that the tectonic setting of the plutons was an environment of conversion from compression to extension in Indosinian period.

Abstract:Abstract：The Laojunshan Intrusion is situated in northern Qinling orogenic belt, which is located in southern Heigou-Luanchuan faulted zone in the Qinling orogenic belt. Based on the contact relationship, the evolution of the intrusion can be divided from early to late into three stages, i.e., small-porphyry fine-medium-grained biotite monzonitic granite, mid-porphyry medium-coarse grained biotite monzonitic granite and big-porphyry medium-coarse grained biotite monzonitic granite. They are characterized by concentric zoning. All the three stages of granites have similar mineralogical and geochemical characteristics. They are composed of potash feldspar, plagioclase, biotite and quartz, but there are obvious differences in the rock texture. They are characterized by high Si (>70%) and alkali (8.28-9.53 %) and low Ca (0.68%-2.42%) . They also have relatively high Ba, Sr, Nb, Zr, Th and Rb concentrations and comparatively low Co, Ni, Cr, V and Sc concentrations, belonging to I-type granite. The SHRIMP U-Pb zircon dating of the second and third stage rocks yielded ages of 111±1Ma（MSWD=0.41） and 108±1Ma（MSWD=0.39） respectively, suggesting Late Mesozoic. It is inferred that the Laojunshan Intrusion resulted from large-scale late Mesozoic magmatism in eastern China.

Abstract:Abstract：The Shibaogou granitoid pluton, consisting of porphyritic monzogranite and middle-fine-grained monzogranite as well as mafic magma enclaves, is located in the southern margin of the North China Craton. The zircon LA-ICPMS dating of the porphyritic monzogranite and mid-fine-grained monzogranite from this pluton yielded ages of 156±1Ma (MSWD=0.34, N=15) and 157±1Ma (MSWD=0.10, N=17), respectively. The rocks are of high K calc-alkaline series and belong to metaluminous to weak peraluminous I-type granite with A/CNK being 0.82～1.02, Na2O+K2O 7.61%～8.91% and K2O/Na2O 1.02～1.48. Their REE and trace elements are enriched in large ion lithophile elements (LREE, Rb, Ba, K and Pb), and depleted in high-field strength elements (HREE, P and Ti), with slightly negative to positive anomalies of Eu (δEu＝0.81～1.12). Zircon Hf isotopic compositions of the porphyritic monzogranite and middle-fine-grained monzogranite are mainly characterized by εHf(t) values of -22.6～-8.3 and -26.9～-12.4, and the two-stage model ages of 2.64 to 1.73 Ga and 2.91 to 1.99 Ga, respectively. Geochemistry and zircon Hf isotopic compositions show that they were derived from an ancient continental crust (probably Archean Taihua Group), with the addition of juvenile components.

Abstract:Abstract：The Dexing ore concentration area located at the juncture between Qiantang body and Jiangnan body is one of the large ore concentration areas along the Qinhang metallogenic belt of eastern China. It includes Tongchang, Fujiawu and Zhushahong porphyry Cu-Mo-Au deposits, Yinshan Ag-Cu -Pb-Zn polymetallic deposit, Jinshan gold deposit and other large and superlarge ore deposits. Based on systematic field geological survey and sample acquisition, this paper presents in situ zircon U-Pb and Hf-isotopic data of Tongchang, Fujiawu, Zhushahong and Yinshan deposits: 171±1.2 Ma for Tongchang, 172 ±0.68 Ma Ma for Fujiawu, 173 ±1.3Ma for Zhushahong, and 176±1.5 Ma Ma for Yinshan. These data show that all the granodiorite-porphyry bodies were formed in the Early-Middle Jurassic period. Zircon in-situ analysis of four samples gives the average εHf(t) values of (4.34~5.54) with limited variation and Hf crustal model ages of 861Ma, 876 Ma, 904 Ma and 941Ma. The Zr/Hf ratios are close to the Zr/Hf ratio of the upper mantle . Zircon Hf isotopic composition suggests that the parental magmas of the rock bodies were mainly derived from a young mantle and partly mixed with old continental crust rock during the evolution. Mantle material in the Dexing ore concentration area played an important role in the formation of the granodiorite porphyry. The most important rock-forming and ore-forming period of the four deposits should be in 170 ~ 175 Ma. The continual magmatic hydrothermal activation might have been the important factor responsible for the formation of the Dexing ore district.

Abstract:Abstract：The Nantai Mo polymetallic deposit is a typical porphyry-skarn deposit in North Qinling Mountains，the magmatic rocks in this deposit include granite-porphyry, quartz porphyry veins and explosion breccia, and there occur porphyry-type and skarn-type Mo polymetallic mineralizations within and around the granite-porphyry body. The granite-porphyry from the Nantai Mo polymetallic deposit is dated at (151±1)Ma（N=12，NSWD=0.32）by using zircon U-Pb LA-ICPMS. Six molybdenites samples from the deposit yield Re-Os isotope model ages ranging from (146±2)Ma to (151±2)Ma，with an weighted average of (148.8±1.7)Ma (N=12，NSWD=0.84). The granite age and the metallogenic age are consistent with each other within the error limits, suggesting that the Nantai Mo polymetallic deposit was formed in the late Jurassic period, consistent with the formation epoch of the main porphyry-skarn type molybdenum deposits on the southern margin of North China Block. The zircon Hf isotope composition of the granite-porphyry has a large variation, with initial ratios of 176Hf/177Hf ranging from 0.281 864 to 0.282 454, εHf(t) from -28.8 to -7.9, and two-stage model ages from 2654Ma to 1506Ma. These data suggest that granite-porphyry was probably derived form several sources dominated by curstal materials with the addition of small amouts of mantle materials, and the old crust was dominated by the contribution of juvenile components. Therefore, the source of the metallogenic material for the Nantai Mo polymetallic deposit was probably the same as that of the granite.

Abstract:Abstract：Detailed LA-ICP-MS U-Pb dating and LAM-MC-ICPMS Lu-Hf isotope analysis were carried out for zircons in a mica quartz schist sample from Guixi area of northern Cathaysia Block, South China. These zircons are characterized by zoning, higher Th/U ratios (>0.4), HREE enrichment and positive Ce and negative Eu anomalies, and are similar to magmatic zircons in some aspects. Zircon U-Pb geochronological results of the mica quartz schist show a peak at ~775 Ma and a secondary peak at ~840 Ma, probably corresponding to two large-scale magmatic events. εHf(t) values for the ~840 Ma zircons could be divided into two intervals with both negative or positive values, whereas εHf(t) values for the ~775 Ma zircons are all negative values. Combined with previous zricon U-Pb dating and Hf isotopic results, the authors conclude that the Neoproterozoic magmatism in the Cathyasia Block mainly found expression in recycling of ancient crustal components. Nine zircon grains from the mica quartz schist with the other secondary peak at around 1770 Ma have very constant U-Pb ages and Hf isotopic composition, implying that they were most probably captured from the Paleoproterozoic basement rock.

Abstract:Abstract：Using a petrogeochemical means, we recognize a diorite-quartz diorite-tonalite suit in the northern margin of the North China craton, some 100-180 km south of the Permian Solonker ophiolite-decorated suture. The granitoid rocks are all sodic, consistent in composition with a plutonic arc. SHRIMP dating of zircons from two diorites yielded weighted mean 206Pb/238U ages of 293±4 Ma and 266±4 Ma. A quartz diorite and a tonalite are dated at 272±7 Ma and 277±3 Ma respectively. These Permian granitoid rocks were thus emplaced continuously. They are nearly coeval with, or slightly younger than, the Solonker SSZ (supersubduction zone)-type ophiolite. On the basis of a specific tectonic setting and an age relationship with the Permian Solonker SSZ-type ophiolite, we interpret the sodic granitoid suit investigated, together with near-contemporaneous andesites of the area, to form a continental margin arc.

Abstract:Abstract：Located in Yangchun basin of western Guangdong Province, the Shilu deposit has developed oxidized Cu and skarn Cu-Mo ore bodies. The skarn ore body genetically is associated with the Shilu granodiorite. Direct Re-Os dating of molybdenite collected from the skarn ore bodies in the Shilu deposit was carried out to better understand the age of mineralization. The results show that the five molybdenite samples from quartz-vein-type ore have 187Re-187Os model ages ranging from (104±1.5) Ma to (104.6±1.5)Ma, with an average of (104.34±0.66)Ma and an isochron age of (104.1±1.3)Ma, consistent with the age of the related granodiorite (107±0.72Ma), which implies that the mineralization took place in the early Cretaceous. Based on previous studies, it is suggested that the Shilu skarn Cu-Mo deposit was formed later than 50Ma when the Jurassic Cu-Fe deposits in Yanchun basin were generated, thus belonging to the large-scale Cretaceous mineralization in South China. It was formed in a lithosphere extension tectonic setting, which was different from the setting of the Jurassic Cu-Fe deposits in this area.

Abstract:Abstract：The Yajishan Mo (Cu) deposit is located in southern Xilamulun Mo (Cu) metallogenic belt on the northern margin of North China block, which is one of the largest Mo metallogenic belts in China. Its major ore bodies occur in the vein like or cataclastic form in the monzonitic granite, strictly controlled by EW- and NE-striking faults. The deposit is obviously of the quartz vein type, and the sulfides in ore veins are dominated by molybdenite, pyrite and chalcopyrite and show veined and disseminated forms in the monzonitic granite. The authors carried out molybdenite Re-Os dating to better understand the mineralization time. Re-Os dating of seven different types of molybdenite separates from the major Mo mineralized bodies gave a weighted average model age of 241.1±1.4 Ma, and six samples of the same type yielded isochron age of (240±3.8) Ma. The Re-Os isochron age represents the ore-forming time of the Mo (Cu) deposit and constrains the age of the monzonitic granite to Early-Middle?Triassic. This result not only provides new evidence for the study of molybdenum deposits in the Xilamulun Mo (Cu) metallogenic belt but also has important significance for discussing the large-scale mineralization in Early-Middle Triassic on the northern margin of North China block. The corresponding geodynamic background was the closure of the Paleo-Asian Ocean.

Abstract:Abstract：Located in eastern Yanliao metallogenic belt, the Siboozi-Liubozi molybdenum-copper deposit in Qinglong County is a newly-discovered medium-size molybdenum-copper deposit. Molybdenite occurs as veinlets, stockworks and disseminations in the skarn hosted in quartz sandstone and dolomite of Changcheng System. Molybdenum mineralization is closely related to silicification. Ore bodies occur in stratoid, veined and lenticular forms. Precise Re-Os dating of molybdenite from the molybdenite-quartz vein in ore was studied in this paper. The results show that the Re-Os model ages of seven samples range from (191.6±2.7) Ma to (196.0±2.9) Ma, with the weighted mean age of (194±1) Ma, and the Re-Os model ages of two samples range from (121.1±1.8) Ma to (125.9±1.9) Ma, suggesting that the main metallogenic epoch of the Sibozi-Liubozi molybdenum-copper deposit was formed in the earliest Jurassic period (196～192 Ma) and that molybdenum mineralization was probably related to granite-porphyry (196～190 Ma) intrusive activities of Laoshangjia and Wubozi. Molybdenum metallogenesis of Lower Cretaceous (121～126Ma)?in the ore district is the latest data reported in Yanliao area. The rhenium values of molybdenite samples are in the range of 6.475～6.923μg/g and 38.74～71.358μg/g, implying that Mo and Cu were derived not only from the crust but also from the mantle-crust mixed source.

Abstract:Abstract：The Middle-Lower Yangtze River belt is one of the large-scale Mesozoic metallogenic areas in eastern China and also an important Cu-Fe-Au-Mo metallogenic belt in eastern China. The polymetallic Cu-Fe deposits in southeast Hubei area constitute an important part of the Yangtze River belt; nevertheless, studies of rock body chronology and thermal chronology remain very insufficient. Biotite and hornblende of the Tieshan rock body related to the skarn-type Fe deposits in Daye of Hubei Province yield 40Ar-39Ar plateau ages of 133.0±1.0 Ma and 137.0±2.0 Ma and isochronal ages of 133.4±1.5 Ma and 137.3±1.6 Ma respectively. An integrated study of available petrological, geochemical and rock body U-Pb ages led the authors to believe that the rock body ages of southeast Hubei area are the same as the ages of the Yangtze River belt, and the skarn-type Fe mineralization in Daye of Hubei Province was associated with lithospheric extension and thinning during the Late Mesozoic in eastern China. Meanwhile, utilizing the rock body cooling rate theory (the mineralization scale retro-correlation to the rock body cooling rate), the authors found that, although the cooling rate of the Tieshan rock body is rather higher in comparison with the cooling rates of the main mineralization rock bodies in Tongling, small shallow plutons could be complemented by ore-forming fluids and heat energy of deep magma chamber.

Abstract:Abstract：The Gejiu polymetallic tin ore district in Yunnan Province is the largest tin deposit in the world, and the Kafang copper (tin) deposit is a component part of this ore district. The stratoid ore body of the Kafang copper (tin) deposit, closely related to meta-basalt, is characterized by enriched copper. The basalt has been altered and the alteration intensity is related to the copper mineralization. This paper presents a new 40Ar-39Ar phlogopite age for the meta-basalt in the Kafang tin-copper deposit in order to constrain the timing and duration of the alteration of basalt and the mineralization. Phlogopite yielded 40Ar-39Ar plateau age of 85.49±0.63 Ma, isochronal age of 85.62±0.42 Ma, and inverse isochronal age of 85.59±0.81 Ma. These ages are substantially consistent with each other, pointing to late Cretaceous. These results are coincident with the data obtained from the Gejiu polymetallic tin-copper deposit.

Abstract:Abstract：Gejiu is one of the largest polymetallic tin ore concentration areas in the world and belongs to a granite-related magmatic-hydrothermal system. Its ore-controlling structural characteristics are very obvious. In this paper, the authors selected the joints developed in the Songshujiao orefield, Laochang orefield and Kafang orefield as the research objects, measured and statistically analyzed the modes of occurrence of joints developed in tunnels in combination with surface, and made a comparative analysis of the rock-controlling structures and ore-controlling structures. Statistics show that the variation regularity of the predominant joints within the orefields has several characteristics from north to south and in vertical direction： 1) the main predominant ore-hosting joints are in NE, NW, NS and EW directions, especially the NW-trending joints constitute an important ore-hosting structure in recent exploration and development of the western segment of the ore concentration area. 2）The predominant directions of the joints developed in granite are different in the north and south parts of this mining area. The directions of joints in the north part are single and concentrated, being mainly NW306°-312° and NE45°, while orientations of the joints in the south part are complex and are mainly NE50°, N-S, EW, NW312°-324° and WNW280°. 3) Statistical measurements and analyses of the joints in the carbonate rocks suggest that the joint development in the north segment is relatively simple, while that in the south part of the mining area is complex. 4) The joints in the Songshujiao orefield show some regularity in the vertical direction. From surface to the depth, the orientation of joints in carbonate strata is NE50° in the shallow part and NS-striking in the depth; the orientation of joints in the granite is mainly NW306°-312°in the shallow part and NE45° in the depth. The regional stress field of middle-late Yanshanian metallogenic period in Gejiu area was NW-SE trending compressive stress and then converted into the NS trending reverse shear stress. The newly discovered NW-trending ore-hosting joints constitute an important structure in the west segment, and the scales, advantages and origins of the ore-hosting joints in the north segment and the south segment of the mining area are obviously different. These phenomena deserve much attention in the further exploration and prospecting work. The NE and NS trending joints connected the granite body with carbonate rocks and served as the channels of heat, water and ore source. The results obtained by the authors will provide geological structural evidence for the relationship between ore field structures and mineralization and can guide further ore-prospecting work in the depth and the outskirts of the ore district.

Abstract:Abstract：This paper aims at reporting the petrology and the geochemistry of the buried granite stock in Dajinshan area, which is composed mainly of medium to fine grained biotitic granitic rock and porphyritic biotic granitic rock. These granites are characterized by richness of silica and alkali and depletion of magnesium and calcium. In this study, all samples from Dajinshan are high-K calc-alkaline rocks, which are enriched in Rb, Th, U and depleted in Nb, Eu, Ti in the primitive mantle-normalized spidergrams. The REE values of medium to fine grained biotite granite and porphyritic biotite granite are 203.36×10-6~248.42×10-6 and 243.76×10-6~255.08×10-6 respectively. The medium to fine grained biotite granite body is slightly enriched in HREE whereas the porphyritic biotite granite is enriched in LREE. They all show prominent negative Eu anomalies with δEu values being 0.004~0.009 and 0.059~0.13. The εHf(t) values and two-stage Hf model ages of medium to fine grained biotite granite and porphyritic biotite granite are -2.05~-8.64, -0.92~-6.57 and 1277~1692Ma, 1204~1556Ma, respectively. Based on regional geological and granite geochemical data, it can be concluded that the Dajinshan granites were derived from the partial melting of the Mesoproterozioc continental crust under a crustal extension geodynamic setting during the Late Yanshanian period.

Abstract:Abstract：The main purpose of this fundamental research is to reunderstand Late Jurassic Manketou Obo Formation and Early Cretaceous Manitu Formation as well as Baiyingaolao Formation in Huiyin Obo area of Dong Ujimqin Banner, Inner Mongolia. Several sets of experiments were carried out to test the validity of the ages of three formations; these formations are comparable with Chagannuoer Formation and Bulagehada Formation from “1∶250000 Regional Geology Survey in Hesigewula Farm”. On such a basis, the authors have reached the conclusion that further research into the Mesozoic volcanic rocks in Huiyin Obo is necessary.

Abstract:Abstract：The Indosinian granites in the periphery of the Shilu iron deposit belong to the Changjiang granitic body. These granites are mainly monzonitic granites. They lie between metaluminous field and weakly peraluminous field, and belong to high-K calc-alkaline series and shoshonitic series. The granites have ∑REE values of 134.96-241.05 ppm and show relatively strong enrichment of light rare earth elements (LREE/HREE=4.44-9.67), with higher (La/Yb)N ratios of 3.95-10.69 and negative Eu anomalies (δEu=0.28-0.57). Mantle-normalized trace element spidergrams of all samples show obvious negative anomalies of Ba, Nb, Ta, Ce, Sr, P and Ti. The obvious negative Ba, Sr and Eu anomalies indicate that plagioclase existed in the source region or the granites experienced plagioclase crystallization and fractionation. The granites have a range of (87Sr/86Sr)i from 0.710852 to 0.715492 except for one sample (SL10-136) whose (87Sr/86Sr)i value is 0.706364 , a narrow εNd(t) value range of -7.3 to -9.1 and TDM2 model ages of 1.5–1.9 Ga, indicating a homogeneous source and partial melting of the Mid-Proterozoic Baoban Group. The granites were formed in a post-orogenic environment. Based on previous investigation of granite in Hainan Ireland, this paper deals with ireland-arc, syn-orogenic and post-orogenic granitoids in Hainan Ireland. The Hercynian to Indosinian granitoids can be compared with granitoids in northern Vietnam.

Abstract:Abstract：Located on the southern margin of Echeng batholith in the southeastern Hubei ore concentration area, .the Chengchao iron deposit is the largest skarn iron deposit in the Middle–Lower Yangtze River Valley metallogenic belt. The ore deposit occurs along the contact between granitoids and carbonates or between granitoids and diorites. Ore bodies, granitoids and skarns have close contact relationships. REE analyses show that the chondrite-normalized REE patterns of garnets, epidote and magnetite ores in the Chengchao iron deposit are similar to each other and enriched in LREE (light REE) with Eu positive anomaly and without Ce anomaly, implying that they were formed in an oxidation environment by magmatic fluids characterized by high temperature and richness of Eu. The REE characteristics of granitoids, skarns and ores indicate their close genetic relationships. Geological and REE geochemical features show that granitoids, skarns and ore bodies are closely related to each other in time, space and genesis.

Abstract:Abstract：The Leng（shuigou）-Chi（gou）-Se（hepu） gold molybdenum and copper belt of Zhashan area in Shaanxi Province is located in southern Zhashan area and lies in the middle of Xiaomaoling-Douling Proterozoic island chained uplift belt and at the junction of the middle and south Qinling Mountains. With the east-west length of 35.7 km and the north-south width of 7.6 km, this belt contains multiple gold molybdenum and copper deposits related to intermediate and acid magmatic activities of Yanshanian period. Geology, ore body, alteration and mineralization regularities of the Lengshuigou gold copper deposit, the Chigou gold and molybdenum copper deposit, the Sehepu copper deposit and other main deposits are summarized in this paper. They are controlled by the main porphyry rock. On the whole, from the porphyry body to surrounding rocks, there appears molybdenum in the inner part , copper in the outer part and gold in the distal part, constituting a porphyry type–skarn type-cryptoexplosion breccia type-tectonic altered rock type gold molybdenum copper metallogenic series. The discovery of the Leng-Chi-Se gold, molybdenum and copper belt provides direct evidence in search for porphyry molybdenum-copper deposits in middle and south Qinling Mountains, and also broadens the ore-prospecting train of thought and space in Zhashan area.

Abstract:Abstract：The Hongniu deposit is located in the Zhongdian island arc belt of northwest Yunnan and lies in the middle part of southwest Sanjiang region, belonging to the southern segment of the Triassic Yidun island arc belt. This ore deposit is one of the promising copper-polymetallic deposits with vast potential, and its Cu reserves have reached the middle size. Geological features of the ore bodies and element geochemical characteristics indicate that Hongniu is a typical skarn-hornfels type copper polymetallic ore deposit. It has typical alteration zoning and metallogenic element zoning of the skarn type deposit in both vertical and horizontal directions. The?element geochemical characteristics of the skarn are obviously affected by the elements of marble and quartz monzonite porphyry. According to geological features of the ore bodies, the authors also infer that the deep porphyry bodies have great metallogenic potential.

Abstract:Abstract：The Jinchuantang deposit is a large-size skarn-type tin-bismuth deposit in the Dongpo ore field. Little is known about the mineralogical characteristics of the skarn in the Jinchuantang deposit. Based on microscopic observations and electron microprobe analyses, the authors investigated in detail compositional characteristics of skarn minerals in the Jinchuantang tin-bismuth deposit. The results show that the end member of the garnet is composed mainly of grossularite and andradite, followed by spessartite. The composition of pyroxene is dominated by diopside, with minor hedenbergite. The amphibole comprises mainly ferrotschermakite, followed by tschermakite, actinolite and tremolite. Based on the above data, the authors hold that skarn in the Jinchuantang tin-bismuth deposit is mainly calcareous skarn, with minor manganoan skarn. According to the characteristics of skarn minerals, this paper has further discussed the mechanism of cassiterite precipitation, and considered that tin probably replaced Fe3+ in the form of Sn4+ in the octahedron of crystal structure of andradite at the early skarn stage due to the relatively high oxygen fugacity. At the late skarn stage, however, tin dominantly existent as Sn (II) chloro-complex species was transported in fluid with the decrease of the oxygen fugacity. In the process of fluid evolution, the changes of the temperature, salinity, pH and oxygen fugacity were responsible for cassiterite precipitation because the Sn2+ was oxidized to Sn4+.

Abstract:Abstract：The hydrothermal ore-forming process of the Nannihu-Sandaozhuang Mo (W) deposit can be divided into four stages, i.e., from early to late, (1) skarn and hornfels stage, (2) quartz - K-feldspar and retrograde stage, (3) quartz-sulfides stage and (4) quartz-carbonate stage. Based on studies of carbon, hydrogen and oxygen isotopes of different stages, the authors hold that the ore-forming fluid was derived mainly from the magmatic system and subordinately from the carbonate strata with minor organic matter. The atmospheric water probably made very little contribution to the ore-forming process. From early to late stage, the ore-forming process probably experienced immiscibility between melt and volatile-rich hydrothermal fluid, water-rock reaction, and phase separation of CO2 rich gas from ore fluid caused by sudden decompression.

Abstract:Abstract：The Muziyuan tungsten deposit is a medium-size quartz-vein type tungsten deposit in southern Jiangxi Province. The model using surface mica line and quartz line can be used in search for concealed quartz vein type ore deposit. Based on detailed petrographic observations, the authors carried out microthermometric and Raman microspectroscopic studies of fluid inclusions in wolframite-quartz veins of the Muziyuan tungsten deposit. Experimental results show that fluid inclusions in quartz have recorded at least two periods of fluid activities. These two kinds of fluid are of the high temperature, low salinity and low density NaCl-H2O fluid system and the low temperature, low salinity and medium density NaCl-H2O fluid system respectively. In the evolution process of ore-forming fluids in the Muziyuan tungsten deposit, high temperature stage experienced some boiling, resulting in the decomposition of the metal complex in ore forming fluids and ore deposition, whereas the low-temperature phase was mainly subjected to the natural cooling process, and the fluid mineral precipitation resulted mainly from the temperature decrease.

Abstract:Abstract：The Shizhaigou gold deposit, located in Xiaoshan terrain of Huashan-Xiong’ershan massif on the southern margin of the North China Craton, is a small gold deposit discovered in recent years. The strata in the Shizhaigou gold orefield are composed of intermediate-basic and intermediate-acid volcanic rocks of the Majiahe and Xushan Formations of the Mesoproterozoic Xiong’er Group. The intrusions only include minor intermediate-acid intrusive rocks. The fracture zone controls the distribution of the ore bodies. The ores are mainly of massive, disseminated and breccia structures, and classified as altered rock type. The wall rock alterations in the deposit include silicification, pyritization, sericitization, carbonatization and chloritization. The evolution of the hydrothermal mineralization system comprised the quartz-pyrite stage, quartz-polymetallic sulfides stage and quartz-carbonate stage, and gold was manly deposited in the quartz-polymetallic sulfides stage. Fluid inclusions of the quartz-polymetallic sulfides stage are mainly liquid-rich aqueous two-phase, vapor-rich aqueous two-phase and CO2-bearing three-phase inclusions, and their homogenization temperatures and salinities vary from 260°C to 320°C and from 2.0 wt% to 9.0 wt% NaCl equivalent, respectively. The fluid inclusions of the quartz-carbonate stage are mainly composed of liquid-rich aqueous two-phase inclusions, with homogenization temperatures being 140 ~ 200°C and salinities 5.6 wt% ~ 8.1 wt% NaCl equivalent, respectively. The immiscible action of ore-forming fluid was the dominant factor for metallic sulfide deposition. The δ34S values of sulfides within the ores vary from +3.7‰ to +7.7‰, with an average of +5.6‰. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sulfide are in the range of 16.951 ~ 17.035, 15.370 ~ 15.466 and 37.188 ~ 37.512, respectively. The composition of lead isotope in the ores are similar to that of the Taihua Group, and higher than that of the Xiong’er Group but lower than that of the Huashan intrusive rock, indicating that the ore-forming material of the Shizhaigou gold deposit originated from the Taihua Group.

Abstract:Abstract：The Budunhua Cu deposit is a porphyry-hydrothermal vein type composite deposit in the middle-south part of the Da Hinggan Mountains. The deposit consists of the southern Jinjiling porphyry Cu ore block and northern Kongqueshan hydrothermal vein-type Cu ore block. Based on a detailed analysis of geological characteristics and a study of hydrogen, oxygen, sulfur, and lead isotopes in hydrothermal minerals, this paper has discussed the origin of ore-forming fluid and materials and genesis of the Budunhua deposit. Hydrogen and oxygen isotope analyses indicate that the ore-forming fluid in the early ore-forming stage in Jinjiling and Kongqueshan ore blocks was mainly magmatic water, whereas that in the late ore-formaing stage was probably a mixed fluid of magmatic and meteoric water. Sulfur isotope analyses show that the Jinjiling ore block is relatively rich in 34S, with sulfur isotope composition of ore-forming fluid being +2.54~+2.60‰, while the Kongqueshan ore block is relatively depleted in 34S, with sulfur isotope composition of ore-forming fluid being -1.84~-1.71‰. The sulfur isotope composition of the two ore blocks suggest a deep-seated source, and the lead isotope results display crust-mantle mixing characteristics closely related to magmatism. With the regional geological evolution history of the middle-south part of the Da Hinggan Mountains as a premise, the mineralization of the Jinjiling and the Kongqueshan Cu ore blocks in the Budunhua Cu deposit should be mainly related to fluid mixing which led to the precipitation of metal sulfides.

Abstract:Abstract：The Tiantang Cu-Pb-Zn polymetallic deposit of Guangdong Province occurs at the northeast edge of Yangchun basin, which is located in the Qinzhou-Hangzhou metallogenic belt. On the basis of geological field observations, the authors selected main sulfides in the deposit as the object to study the mineralogical characteristics, and analyzed the S-Pb isotopic composition so as to trace and discuss the sources of ore-forming metal materials. Representative results 1 of electron microprobe analysis show that Fe and S content and atomic ratios of S/Fe in pyrite are higher than theoretical values, there exist Cu, Sb and As, and the ratios of Co/Ni are between 0.21 and 2.28, usually higher than 1, suggesting a hydrothermal environment of relatively high sulfur fugacity; in sphalerite the Zn content is lower than theoretical values while the atomic ratios of S/Zn and the S content are higher than theoretical values, with the existence of some Pb, Fe, Co and Se; some elements in galena, chalcopyrite and other sulfides occur in isomorphism. δ34S values of the main ore minerals of this deposit have a narrow range of -2.1‰~2.6‰,with peaks at -0.8‰~0.4‰, showing tower-shaped distribution effect and features of magmatic sulfur. Lead isotopic compositions of ores are basically coincident, and 208Pb/204Pb, 207Pb/204Pb and 206Pb/204Pb ratios of ores vary from 38.765 to 39.137, 15.523 to 15.751 and 18.450 to 18.667, respectively. These lead compositions indicate that the ore-forming materials not only had features of the lower crust or the upper mantlebut also had characteristics of the upper crust, indicating that there should have been several sources for ore-forming materials in the Tiantang deposit, belonging to crust-mantle mixture, and the ore deposit was formed due to lithospheric extension in southern China since the Late Mesozoic.

Abstract:Abstract：The Xiazhuang uranium orefield is an important uranium producing area in Nanling region, where there exist many ore deposits. To solve the much controversial problems of the origin of uranium and the ore-forming fluid, this research is focused on Sr, Nd and Pb isotopic geochemistry of the gangue minerals. The results show that the carbonate has rich radioactive lead. The lead and uranium mainly came from such granitic rock bodies as Maofeng granite. The compositions of Sr and Nd isotope show that the ore-forming fluid was mainly derived from the crust. The water-rock interaction between the ore-forming fluid and the basic dike rock during the upward migration of the ore-forming fluid and the precipitation of uranium formed the feature of binary composition of the gangue minerals.

Abstract:Abstract：The Sishanling iron deposit is located in the northern margin of North China platform and geographically lies in Benfen area, Liaoning Province. The ores are composed of magnetite and hematite and controlled by Anben Formation of Achean Cigou Group, the sedimentary facies is of the oxide-silicate phase. Through the study of element geochemistry of the main minerals, ores and wall rocks, the authors have obtained some useful information： Metamorphic facies has reached low amphibolite facies, and the BIF can be classified as mafic volcanic-muddy sandstone-ferrosilicic sedimentary formation. The metamorphic volcanic rocks are characterized by oceanic tholeiite. The shale-normalized REE patterns of the ores display depletion of light REE relative to heavy REE, high ratios of Y/Ho and distinct positive anomalies of La, Y. Eu shows stronger positive anomalies in comparison with the other main BIFs in North China platform. The geochemical information of the BIF shows that the ore-forming elements came from the mixed solution of volcanic-hydrothermal solution and sea water, and that the hydrothermal solution was related to the mantle material.

Abstract:Abstract：The Washan iron deposit is a representative porphyrite iron deposit. There are two types of intrusions: One is gabbro-diorite porphyrite closely related to the iron mineralization and serves as the host rocks, and the other is granodiorite porphyry cutting across the ore body, which has been rarely studied. Detailed zircon LA-ICP-MS trace element measurement was performed on these two intrusions. The two intrusions have similar chondrite-normalized REE patterns of zircons and Yb, Hf and Y values, whereas zircons from the granodiorite porphyry have higher U values and U/Yb ratios. In combination with previous studies of isotope geochemistry, the authors infer that these intrusions have similar sources, and much crust material was involved in the formation of granodiorite porphyry during the ascending process. Zircon Ce（Ⅳ）/Ce（Ⅲ）ratios of the granodiorite porphyry are concentrated in the range of 0-100, lower than the values of zircons (>300) from the granite related to the porphyry Cu-Au mineralization; nevertheless, they have similar characteristics of δEu (>0.4). Thus, it is not certain whether the granodiorite porphyry had the potential to form copper and gold deposits, and hence further researches are needed concerning the possible relationship between the granitic stocks and copper and/or gold mineralization.