Abstract:The Jiusangou ore deposit in Yanbian area of Jilin Province is a typical epithermal-mesothermal gold deposit. In this study, detailed studies were carried out by means of zircon LA-ICP-MS U-Pb dating of the host rock of the Jiusangou gold deposit, i.e., altered diorite porphyrite. The analysis yielded U-Pb concordant ages of single zircons from 103 Ma to 116 Ma, with weighted mean age being 109.3±2.1 Ma(MSWD=7.0,n=18), which can be regarded as the rock-forming age of diorite porphyrite. The ages obtained can be subdivided into two groups: 112～116 Ma(Mean=113.1±1.1 Ma, n=9,MSWD=0.55, reliability=0.82)and 103～110 Ma(Mean=105.8±1.8 Ma, n=9, MSWD=2.2, reliability=0.022). According to the age of zircons and the crystal form of zircons or CL image characteristics, it is preliminarily determined that the former group of ages should represent the crystallization age of the main body of the diorite porphyrite, whereas the latter group of ages should represent the end of the magmatic evolution. According to regional metallogenic regularity and previ-ous achievements, the authors hold that the thermal event of the gold mineralization took place before 106 Ma. The results of this study suggest that the metallogenic environment was the subduction and extinction of Izanaqi plate towards the ancient Asian continent in late Early Cretaceous and the conversion process of slip or extension structures in eastern China continental margin during the Late Yanshanian orogenic movement.

Abstract:Early Carboniferous arc volcanic rocks lie in Hongyan area of northwestern Xiao Hinggan Mountains. The volcanic rocks consist of basalt, andesite, dacite and rhyolite. Petrological and geochemical studies indicate that the volcanic rocks are of typical calc-alkaline type and display relatively high-K features. They are enriched in LREE (LREE/HREE=4.19～13.83) and LILE (Rb, Ba, Th and U) with obvious depletion of Nb,Ta and Ti, which suggests an active continental margin environment. The authors hold that the volcanic rocks of Hongyan area were derived from partial melting of enriched lithosphere mantle and experienced mainly crystallization differentiation with a small extent of lower crust assimilation(AFC-type processes). In combination with regional structures and geochemistry of volcanic rocks, it is concluded that the Early Carboniferous volcanic rocks of Hongyan area were probably formed in a pre-collision subduction environment and might have been related to the collision and collage between Erguna-Xingan and Songnen blocks.

Abstract:The Tangtang granite occurs in the western margin of the Yangtze platform and mainly consists of plagioclase granite. In order to reveal the significance of its petrogenesis, the authors studied the SHRIMP U-Pb dating of zircon and geochemistry of the granite. Geochemical and petrologic data show that the Tangtang granite is characterized by high silicon (SiO₂=72.70%～77.95%), high alkali (ALK=5.68%～7.32%) and peraluminous nature (ASI=1.41～1.78), the average of K₂O/Na₂O ratios is 1.18, and the content of CaO and MgO is very low. Thus, the granite is a typical high-K calc-alkaline S-type granite. It has low REE concentrations and obvious difference between LREE and HREE (LREE/HREE=2.71～4.09), and its trace elements are different from those of the crust. SHRIMP U-Pb dating of the magmatic zircon yielded the age of 1 063.2±6.9 Ma, which should be regarded as the formation age of the granite, and hence the granite was probably related to the Grenville orogenic event. Based on these geochemical characteristics, this paper deals with the petrogenesis of Tangtang granite. It is suggested that the granite was formed by partial melting of argillaceous rocks in the crust. The pattern of bimodel magmatic rocks and the Al₂O₃-SiO₂ diagram both indicate that the formation of Tangtang granite was closely related to the rift environment. The result is consistent with the tectonic setting of 1.0 Ga in the western margin of the Yangtze platform and also corresponds to the Rodinia supercontinent convergence.

Abstract:Using geochemical methods, the authors investigated the provenance of Middle Permian Zhesi Formation sandstone and its tectonic setting in northeast Inner Mongolia. By analyzing major elements, trace elements and rare earth elements, it is found that the sandstone samples are all characterized by high SiO₂, Al₂O₃, Fe₂O₃ and low CaO, MgO, with their values being 67.87%～71.94%, 14.57%～15.61%, 2.61%～6.20%, 0.31%～0.58% and 0.80%～1.93% respectively. The upper crust normalized spider diagrams are characterized by enrichment of LILE such as Ba and Sr and depletion of HFSE except for Zr and Y. The trace element analysis demonstrates the obvious enrichment of LREE relative to HREE, with significant Eu anomalies, (La/Yb)_n=5.08～8.67, Eu/Eu^*=0.56～0.77. The provenance of the Middle Permian Zhesi Formation sandstone in the work area might have been derived from felsic rocks of the upper crust, including granites. The tectonic setting of the provenance of the Middle Permian sandstone in the work area was a continental island arc.

Abstract:The origin of CO₂ and the alteration of CO₂ into clay minerals in eastern Shijiutuo symon fault of Bozhong depression were studied in this paper. The elevated δ¹³C and R/Ra values show the mantle-derivation of CO₂. The basin-controlling deep fault was the main migration pathway of CO₂ fluid. CO₂ fluid injection had obvious impact on clay minerals. CO₂ late injection caused obvious thermal fluctuation and brought out the result that the montmorillonite of the illite/montmorillonite mixing layer was 15%～30% lower than that of mudstone at the nearby depth. Because of late accumulation of CO₂, acidic environment of reservoir bed lasted for a long time, which promoted dissolution of feldspar and formation of kaolinite. Acidic environment inhibited illite in favor of the transform of other clay minerals into kaolinite. The CO₂-bearing reservoir bed was characterized by high authigenic kaolinites and low illite, which played a decisive role in reservoir quality improvement.

Abstract:The Nixiong ore field, located in the Longgeer-Gongbujiangda fault uplift zone, is an important part of Coqen-Shenzha iron and copper metallogenic belt. The Gunjiu iron deposit lies in the northwest of the Nixiong ore field. The ore bodies mainly occur in the contact zone, which lie between the intrusive granodiorite and mon- zogranite and the Permian Dibucuo Formation, with some also located in the interlayer fracture zone of Dibucuo Formation. The main metallic minerals include magnetite, hematite and maghemite, with small amounts of limonite and goethite, whereas the skarn minerals such as grossular, andratite, diopside, sahlite, ferrosalite, serpentine, phlogopite, actinolite, epidote and chlorite are developed in the Gunjiu iron deposit. Among these minerals the phlogopite is closely associated with magnetite. Electron microprobe analysis and ⁴⁰Ar-³⁹Ar dating of phlogopite were conducted in this paper. Electron microprobe analyses show that the phlogopite from the Gunjiu iron deposit is rich in magnesium but low in iron, with Mg/(Fe +Mg+Mn+Ti) value being 0.90～0.94. The ⁴⁰Ar-³⁹Ar dating of phlogopite does not yield a plateau age or isochron age but a total age of 112.3 Ma. The value represents the time that magnetite started to precipitate and is well consistent with the published LA-ICP-MS zircon U-Pb age of 113.6±1.6 Ma and 112.6±1.6 Ma from granodiorite and monzogranite. The result suggests that the iron mineralization took place in late Early Cretaceous at about 113 Ma. Different from iron mineralization, the copper mineralization mainly occurred in early Late Cretaceous at about 87 Ma. Combined with regional geology and the published data, the authors hold that the Gunjiu iron deposit is related to the southward subduction of Bangong Co-Nujiang Ocean crust. In late Early Cretaceous (113 Ma), the Gangdise and the Qiangtang continental crust started to collide. The subducted oceanic crust of Bangong Co-Nujiang began to rotate under the diving inertia and/or gravity drag. Because of the rotation of the oceanic crust, the asthenospheric fluids were upwelling and caused partial melting of the lithospheric mantle and the overlying crust due to the tremendous heat. At last there formed the mixed magma, which intruded upward under the back-arc extensional condition, forming intrusive rocks and fractionated a large number of ore-forming fluids. Meanwhile, the ore-forming fluids met the stratigraphic formation. There occurred contact metasomatism and eventual formation of the magnetite deposit.

Abstract:The deep continental lithosphere, which includes the lower crust and the lithospheric mantle, is a very important layer in the earth's interior. The minerals comprise lower continental crust and lithospheric mantle are mainly nominally anhydrous minerals (NAMs) such as clinopyroxene, orthopyroxene, feldspar, olivine and garnet, and could contain very small and variable amounts of water in the structure as hydrogen-related minor defects; nevertheless, such trace amounts of water can disproportionally affect many physical and chemical properties and play a vital role in geodynamical processes. Knowledge of water distribution in the deep earth may help us understand the interior processes and the evolution of the earth. In this study, using Fourier transform infrared spectrometer (FTIR) analysis, the authors obtained the water content of such minerals as clinopyroxene, orthopyroxene and plagioclase in continental lower crustal granulite xenoliths and mantle peridotite xenoliths hosted by alkali basalts in Junan, Shandong Province. H₂O content ranges from 300×10^-6 to 1 180×10^-6 for clinopyroxene, 80×10^-6 to 169×10^-6 for orthopyroxene, 717×10^-6 to 1 239×10^-6 for plagioclase, and 525 ×10^-6 to 855×10^-6 for bulk rock in continental lower crustal granulite xenoliths; and from 466×10^-6 to 746×10^-6 for clinopyroxene, 187×10^-6 to 304×10^-6 for orthopyroxene, 6×10^-6 to 15×10^-6 for olivine, and 81×10^-6 to 245×10^-6 for bulk rock in mantle peridotite xenoliths. The measured water concentrations of the minerals and bulk rock can roughly reflect the distribution of water in its sources, as evidenced by the following observations: ① EMP and FTIR measurements show no inter- and intra-grain heterogeneities for individual minerals in each sample; ② the cores of the clean, crack-and inclusion-free grains of relatively larger sizes were selected for FTIR measurements; ③ the studied samples were usually fresh and subjected to no alteration. In agreement with previous investigations of similar samples from Hannuoba and Nushan in North China Craton, water content of the continental lower crust is obviously higher than that of the underlying lithospheric mantle.

Abstract:There exists a suite of ultrabasic-basic rock blocks in Luoji Village of Shangri-La County, whose nature is in debate. Petrologic studies show that this suite of rock blocks can be divided into two categories, one is of orthocumulate texture, and the other is of adcumulate texture. Petrologic geochemistry suggests that the rock blocks are low in alkali and oxygen fugacity, but high in calcium content. The original magma is proved to be of the sub-alkaline series with layer cumulate rock characteristics. Mineral composition and chemical composition of the clinopyroxene from ultrabasic-basic rocks suggest that the clinopyroxene is diopside and cation isomorphism is common. Temperature-pressure calculation implies that crystallization occurred under the condition of high temperature (1 084℃) and low pressure (0.15 GPa). The ultrabasic-basic rock blocks in the study area are products of mid-ocean ridge with the composition of oceanic curst, probably being the relics of Garze-Litang suture belt.

Abstract:Based on a comprehensive analysis of S, Pb, H, O isotope geochemical characteristics of the Laochang deep porphyry molybdenum (copper) ore bodies, this paper deals with concealed porphyry metallogenic source material in Lancang of Yunnan Province. Studies show that the main sulfide δ³⁴S values of porphyry molybdenum (copper) ore bodies are between -3.99‰ and +1.8‰, concentrated in a narrow distribution area, with an average of -1.32‰. The test results of S isotope show the crust-mantle characteristics with the mixture derived from the lower crust and the upper mantle. The main lead isotope ²⁰⁶Pb/²⁰⁴Pb ratios of porphyry molybdenum (copper) ore bodies vary in the range of 17.863～18.701, with an average of 18.411. ²⁰⁷Pb/²⁰⁴Pb ratios vary in the range of 15.448～15.733, with an average of 15.628. ²⁰⁸Pb/²⁰⁴Pb ratios vary in the range of 37.753～39.104, with an average of 38.615. These data show that lead was derived not only from the formation but also from the ancient continental crust basement located in the lower part of the ore-bearing layer, deep mantle and volcanic magma. The δ¹⁸O_H2O values of porphyry molybdenum (copper) ore bodies vary between -9.51‰ and +9.41‰, δD values vary between -93‰ and -46.2‰, suggesting that the ore-forming solution of the porphyry ore body was derived from media water from magmatic water and atmospheric precipitation, with the atmospheric precipitation playing the dominant role.

Abstract:The Maoping Pb-Zn deposit, located in Zhaotong City of northeastern Yunnan Province, is a Pb-Zn polymetallic deposit with superlarge-sized potential in Sichuan-Yunnan-Guizhou metallogenic area. The previous studies of its mineralization was weak, and the mineralogical work was especially insufficient. The No. I ore body group occurs in the interformational fault zone of dolomite within upper Devonian Zaige Formation, lying in the west wing of Maomaochang inverted fold. In this paper, based on three-dimensional alternation-lithofacies mapping and petrographic studies of No. I ore body group, the authors established a mineralization-alteration zoning model. The results indicate that the alternation zoning is silicified zone, carbonation + silicification + argillation zone and carbonation zone from the center of ore bodies outwards. Correspondingly, the mineralization zoning changes from massive high grade ore to massive pyrite shell, disseminated-vein-patchy low-grade ore and starry pyrite shell. The mineral assemblage zoning can be divided into Sp+Gn(+Cpy)+Py+Mrc+Apy+Q+Cal assemblage, Py+Gn+Sp+Dol+Fe-Dol+Cal+Q+Ill assemblage, Py+Dol+Fe-Dol+Cal+Q+Sd assemblage and Dol+Cal assemblage. The vertical zoning is not significant, whereas the horizontal zoning is well developed, which is related to the effect of the concentration gradient of vertical physical changes of ore-bearing hydrothermal solution and lithology. Mineralization-alternation can be divided into five stages, i.e., Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴstage. Pyrite shell is the product of early fluid, and banded ore is the product of hydrothermal superposition. The 784 meter level is the ore-forming fluid superimposed striker of Ⅲ stage. Ore-forming fluid temperature of Ⅱ stage is higher than that of Ⅲ stage. The alteration and mineralization zoning model is of great indicating significance for the prospecting of mineral resourcesg and the understanding of the migration, concentration and enrichment of ore-forming fluids.

Abstract:The relationship between the collision and the granite is a problem of common concern among geologists, nevertheless, many misunderstandings exist in the current study. This paper argues that collision is a tectonic event in shallow crust and hence does not belong to the category of tectonic setting. Granite is probably formed by the partial melting of the bottom of the lower crust. The formation of granite needs heat, and the heat mainly comes from the mantle. Collision can't produce granite. The differences of granite geochemistry between syn-collision and post-collision are related to the change of crust thickness caused by collision. So, the discrimination diagrams of tectonic settings, if they contain collision, are completely wrong.

Abstract:Clay minerals of surface sediments in the salt lakes of Hol Xil area were studied in this paper with the purpose of obtaining some recent environmental information of the lakes. The results show that clay minerals are illite and chlorite in surface sedimentary samples, whereas non-clay minerals mainly include quartz, calcite and feldspar together with small amounts of dolomite, aragonite, amphibole and gypsum. Clay minerals with particle sizes smaller than 2 μm in samples are illite (65%～82%) and chlorite (13%～35%), and small amounts of ordered Illite/Smectite (I/S) mixed layer (4%～15%) also exists in local areas. According to the distribution of samples and the combination characteristics of clay minerals, the samples can be divided into 3 districts: mineral combinations of samples in No.1 district and No.3 district are illite, chlorite and ordered I/S mixed layer; however, samples in No.2 district are composed of the combination of illite and chlorite, with no I/S mixed layer. Illite crystallinity in samples was obtained by measuring full width half maximum (FWHM) of 10 Å diffraction peak according to Kübler Index. At the same time, standard curve of illite crystallinity was obtained by international standard illite samples under the condition of D/Max-RC equipment, and the linear equation is y=1.920 4 x-0.154 7 with related coefficient R²=0.982 8. On the basis of the linear equation for illite standard curve, the corrected illite crystallinity Kübler Index (IC) in samples was obtained, and the chemical index of illite in samples was also calculated. The crystallinity values for samples in No.1 and No.3 district are in the range of 0.41～0.59 with the average value of 0.51. However, illite in samples of No.2 district has better crystallinity because its crystallinity values are in the range of 0.25～0.40 with the average value of 0.34, obviously smaller than the values of No.1 and No.3 district. In addition, chemical indexes are all smaller than 0.5, showing that illite belongs to Fe-Mg illite resulting from physical weathering. In conclusion, illite and chlorite, as major clay minerals in samples, suggest that the environmental conditions of the studied lake area are arid and cold, whereas small amounts of ordered I/S mixed layers in local districts, i.e., No.1 and No.3 districts, indicate that these districts have undergone the environment of alternate transient arid and humid in recent years. Furthermore, under acidic medium conditions, small amounts of illite experienced weak hydrolysis which led to the loss of potassium ions from illite crystal lattice, and then transformed to ordered I/S mixed layer, accompanied by the decrease of the crystallinity of illite.

Abstract:Since the beginning of the 21th Century, global mining has got out of the doldrums and entered a new flourishing cycle. As an important mineral commodity, copper has enjoyed accelerated speed of investment and development over the past ten years. Due to the strong demand driven by China, India and other new-emerging economic bodies, the international price of copper has increased rapidly, even with some excessive financial tendencies, and has formed serious price bubble. China's domestic copper reserves have suffered serious shortage, with the external dependence as high as 70%. It has become a severe challenge for China to implement the strategy on the domestic basis and fully take advantage of domestic and foreign resources market under the condition of such an artificially high copper price. In view of such a situation, this paper has systemically summarized the overall trend of the global copper resources and the basic status of China's copper resources and characteristics, with a prognosis of the possible trends of China's copper supply and demand in the next decade. Some advices are put forward, such as increasing late stage exploration and development investment based on the domestic resources with the new mechanism of geological prospecting as the core, so as to convert the copper resources into copper reserves. In addition, we should make full use of market mechanism to achieve the maximization of the interests of national resources and copper industry in the situation of the considerable variation in international copper prices.

Abstract:The apatite (U-Th)/He dating method has been proved to be a powerful and useful tool in the field of low-temperature thermochronology, because it has the lowest available He closure temperature and can reflect the information of the thermal histories at low temperature (40～90℃). This review gives a brief account of the principles, calibrations, laboratory procedures, applications and existing problems of the method, highlighting the progress of the study of radiation damage in recent years. The main content of this paper includes: ① the principle of the radiation damage and the development of the "trapping model"; ② the effect of the radiation damage on apatite (U-Th)/He dating; ③ the development of the new model, i.e., the Radiation Damage Accumulation and Annealing Model; ④ the Applications of the radiation damage.

Abstract:High voltage pulse fragmentation is an advanced sample comminution technology. Based on this technique, SefFrag A G Company in Switzerland manufactured a high voltage pulse fragmentation machine, called SelFrag High Voltage Pulse Fragmentor. This instrument can generate 90～200 kV high voltage, and then shortly discharge the energy from HV working electrode to solids under water. The solids will disaggregate along grain boundaries, inclusions or inhomogeneities, and the minerals such as zircon and apatite in the solid rocks will be completely liberated keeping the morphology intact. Compared with conventional mechanical methods, this highly selective fragmentation has many advantages: ① easy washing with no contamination, ② working in the water with no dust, ③ no loud noise, ④ selective fragmentation without destroying mineral crystals. Currently, the SelFrag High Voltage Pulse Fragmentor is applied in selecting minerals from rocks for geoscience. Besides, it is applicable to circuit waste recycle.