Abstract:Cenozoic volcanic rocks distributed at the Hoh Xil Mts. belong to eastern segment of the Cenozoic volcanic rock belt outcropped along the north Tibetan plateau. In this area volcanic rocks occur mainly in the forms of lava plateau and table mountains, about 40 100m in thickness. Excepting a few high-K 2O rhyolite, trachydacite and trachyte, latites commonly having clino and orthopyroxenes phenocrysts are superior in quantity and distribution. These volcanic rocks are characterized by enrichment of alkalis (specially K 2O) and REE. The volcanic activity took place only in Miocene and might be divided into early (17.3 15.4Ma), middle (14.5-11.7Ma) and late (7.5-6.95Ma) stages based on K/Ar dating. Petrological and geochemical characteristics and ages of volcanic rocks in the Hoh Xil Mts. are consistent with those of Cenozoic volcanic rocks in Tibet. The volcanic activities have been closely related to the lithospheric evolution of the Tibetan plateau since Cenozoic.

Abstract:Ar/39 Ar isotopic chronologic studies of intrusive rocks from Tongling area show that ages of these rocks are all younger than 140Ma and belong to Late Yanshanian period, with granodiorite, quartz monzodiorite, pyroxene monzodiorite and gabbro diabase being 139.8-137Ma, 137-135.8Ma, 138.2-136.6Ma and 133.7Ma respectively. On the basis of 40 Ar/39 Ar isotopic chronologic studies of these intrusive rocks, the authors have also dealt with their K Ar and Rb Sr isotopic ages, and pointed out that the age error was caused by the late hydrothermal alteration and the mixture between mantle magma and crustal magma. In addition, the mineralization ages are found to be close to the smaller ages in 40Ar/39 Ar age spectra, which is in accord with the regional metallogenic character that mineralization took place later than magmatic activity.

Abstract:Pelagic sediments are the place where polymetallic nodules grow.The present paper has systematically studied geochemical characteristics of hydrogenic components of main ore-form-ing elements within sediments in different geochemical fields and at different sedimentary stages as well as the relationship between contents of hydrogenic components and mineralizaton. Studies show that Mn,Fe,Co,Ni and Cu are some fairly active elements existent together in an unified system of polymetallic nodules,sediments and ocean water. When nodules are formed,Mn Fe,Ni and Cu contents in nodules are in negative correlation with their contents in sediments,whereas things are just the opposite for Co content.Nodules in the eastem part of the study area are characterized by rich Mn, Ni, Cu and poor Fe, Co, while sediments asso-ciated with these nodules are relatiyely deficient in Mn,Ni,Cu, Co but rich in Fe, and canthus be called an impoverished geochemical field.Nodules in the western part of the study area are rich in Fe,Co but deficient in Mn,Ni, Cu,whereas their saaociated sediments are corre-spondingly poor in Fe but rich in Mn,Ni,Cu,Co,and can hence be called an enriched geo-chemical field.It is thus known that the impoverished sediment geochemical field is just the best place in search for rich ore nodules.Corresponding to the formation of nodules,the sedi-ments since Early Miocene,in accordance with contents of content ratios of hydrogenic compo-nents,can be divided into three major sedimentary stages.of which No.Ⅱstage shows geo-chemical characteristics of impoverishment,and is the most favorable period for the formation of polymentallic nodules.

Abstract:Wuliga, Pingdingshan and Laozuoshan gold deposits are three important gold deposits in Jiamusi Massif. Studies show that quartz is not only an important gangue mineral but a main carrier of gold as well. Quartz with SiO2content lower than 98% but∑(Al2O3+K2O+Na2O) content higher than 1.3% is auriferous quartz, whose thermoluminescent spectra are characterized by double or multiple peaks. Therefore, these typomorphic characteristics serve as important ore-prospecting indicators for gold deposits and are hence of great significance in evaluation of ore occurrences and broadening of ore-prospecting vista in Jiamusi Massif

Abstract:Micrograined inclusions in Qingyang rock body are both similar to and obviously different from host rocks in such aspects as petrology, mineralogy and geochemistry. The similarity shows their affinity, and the differences reflect the attributes of partial melting relicts of inclusions. There also exist some differences in magmatic dynamic characteristics between Qingyang rock body and its micrograined inclusions, which reveals the state of movement of inclusions in the process of magmatic emplacement. The characteristics of micrograined inclusions provide significant information for the genesis of magmatic rock.

Abstract:There exist large numbers of primary inclusions in quartz phenocrysts within topaz granitic porphyry from Yangbin, Zhejiang Province. Based on large quantities of analytical work in such aspects of the inclusions as their homogenization temperature, salinity and chemical composition, the authors have classified these primary inclusions into five major types, namely melt inclusions, hydroxylated silicate melt fluid inclusions, nonhomogeneous captured polyphase inclusions, liquid inclusions (including high salinity liquid inclusions and low salinity liquid inclusions), and gas inclusions. In addition, the formation mechanism of inclusions in this area are studied with respect to magmatic stage, magmatic disaggregation stage, magma/fluid immiscible stage, and hydrothermal dominant stage, thus convincingly supporting the opinion of magmatic origin for topaz granitic porphyry.

Abstract:The Baguamiao gold deposit in a sort of mesothermal hypothermal carbonate type gold deposit. Quartz, one of the major gangue minerals, is closely related to gold mineralization. According to modes of occurrence, auriferous quartz veins might be divided into three types:(1) bedding quartz veins;(2) ferriferous dolomite quartz veins;(3)quartz veins along NE trending joints. These types show certain differences in compositional characteristics of trace elements and rare earth elements and were formed respectively at different ore forming stages of gold, being evolutional products of gold in the process of ore forming process. Thermometric measurements of inclusions in quartz have provided evidence for mesothermal hypothermal origin of the Baguamiao gold deposit.

Abstract:The Wunugetushan deposit is a large-sized porphyry copper-molybdenum deposit with pyrite as the most abundant metallic mineral. The average decrepitation temperatures of pyrite for three major ore-forming stages (molybdenum, copper, lead-zinc) are 331℃, 228℃and <200℃, which on the whole represent main ore-forming temperatures of three major mineralization stages. Pyrite is characterized by low Co (64.84×10-6) and Ni (15.6×10-6) but very high As (588.6×10-6),diametrically different from pyrite in porphyry copper-molybdenum deposits of China whereas similar to pyrite of sedimentary or stratabound origin in features of trace elements. This suggests to certain extent that some ore-forming substances of the ore deposit had nothing to do with mentle materials. Molybdenite, the only important molybdenum mineral, is dominantly of 2Htype and occurs mainly in the quartz-potash feldspathization zone.Different from most porphyry copper-molybdenum deposits in China, this ore deposit contains very low Re, implying not only high differentiation degree of the rock body but also the derivation of Mo from biotite granite of upper crust remelting origin. Copper minerals are mainly chalcopyrite and subordinately Zn-tennantite and bornite, which mainly occur in the quartzsericite-hydromus-covitization zone. The differences in trace elements of chalcopyrite of different generations reflect variation in ore-forming solutions. Galena and sphalerite mainly occur in the quartz-illite-hydromuscovite zone, with sphalerite deficient in iron (XFeS=4 mol%—8 mol%),and galena containing Ag(0.01%—0.35%).

Abstract:Research on the Guantian pyrite deposit in Guangdong led to the discovery of many sulfate minerals besides pyrite, such as emplectite, aikinite, ourayite, and enargite, totally in excess of ten species. All these species were described with respect to their mineralogical characteristics, and the mineralizing activities in the deposit were grouped into three phases following a comprehensive review of the ore textures as well as features of common and trace elements. Further studies were focused on the genesis of the deposit based on S, H and O isotopes, inclusion homogenization temperatures and other features. It is consequently concluded that the Guantian deposit should owe its formation to the metasomatism at low to intermediate temperatures by the postmagmatic hydrothermal solution along with less meteoric water, suggesting the deposit is a hydrothermal metasomatic vein type one.

Abstract:Boron deposits of eastern Liaoning occur in a suite of Early Proterozoic metamorphic rocks, with boron orebodies existent in magnesian marble.Tourmalines occur in metaleucogranulite, tourmalite and boron orebodies.Mineralogical study of tourmalines shows that there exist Mg-Fe series and Na-Ca series of tourmalines, that tourmalines are characterized by rich Mg and Ca, and that their FeO/(FeO+MgO) and Na2O/(Na2O + CaO) are all lower than 0.5. Tourmalines from different rocks exhibit different mineralogical features, which reflect different formation environments and hence have important significance in indicating rock forming and ore forming process.Genetic analysis suggests that tourmalines were formed during regional metmorphism of amphibole facies.

Abstract:Glauconite has long been considered to be an authigenic mineral formed at specific marine conditions and thus an indicator mineral of marine facies. Nevertheless, with the successive discovery of continental glauconite, it seems necessary to reconsider this viewpoint. Based on statistics of glauconite from different areas and different environments, it is held that glauconite is formed either in marine environment or in continental lake environment, and hence cannot be regarded as a facies mineral. Compared with that formed in marine environment, glauconite formed in continental lake environment is generally characterized by high Al2O3, K2O and low FeO.