Anomalous Enrichment of Silver in Organic Matter of the Songxi Shale-hosted Ag-Sb Deposit in Northeastern Guangdong

The silver contents of organic matter in the host rocks of the Songxi shale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determined using the electron microprobe technique. The silver contents in two types of organic matter, marine vitrinite and solid bitumen, vary in the range from 100×10-6to 350×10-6, which are from tens of times to thousands of times higher than those of the host rocks in the ore deposit. The average silver content of the organic matter is also several times higher than the pay grade of silver for commercial mining of the ore deposit. It is quite obvious that the organic matter of the host rocks in the ore district is characterized by an anomalous enrichment of silver. The results of this study indicate that the silver anomalies in the organic matter have been derived from both the host rocks and the silver-bearing fluids of the Songxi black shale ore source. In the course of sedimentation and later hydrothermal reworking, organic matter was able     

Geological characteristics and metallogenic prospect of marine volcanic rock-type copper deposits in eastern Kunlun Mountains area,Xinjiang

The Katelixi Cu-Zn deposit is a marine volcanic rock-type copper deposit discovered for the first time in the Tokuzidaban Group in eastern Kunlun Mountains area. It is hosted in the Lower Carboniferous Tokuzidaban Group volcanic strata. The orebodies are obviously controlled by the strata and their ore-bearing rocks are a suite of greyish-green mafic tuffs, generally parallel-stratiform, stratoid and lenticular in form, occurring in limestone as well as in the contact between limestone and carbon-bearing siltstone. This ore deposit possesses distinct characteristics of marine volcanic rock sedimentaion. The geological, petrochemical and REE characteristics of its occurrence pro-vide strong evidence suggesting that this deposit is of marine volcanic rock sedimention origin, basically identical to those of some typical marine volcanic rock-type copper deposits in Xinjiang and other parts of China. Marine vol-canic rocks are well developed in the Lower Carboniferous Tokuzidaban strata in eastern Kunlun Mountains area. In addition to this deposit, we have also found a number of copper polymetallic ore deposits or occurrences in associa-tion with marine volcanc activities in many places where there is a good metallogenic prospect. A breakthrough in the understanding of ore prospecting and genesis has not only filled up the gap in prospecting this type of ore depos-its in this area, but also is of great significance in directing exploration of this type of ore deposits in this area.     

Organic Geochemistry of Sedimentary Rock-hosted Disseminated Gold Deposits in Southwestern Guizhou Province, China

Sedimentary rock-hosted disseminated gold (SRHDG) deposits in the Youjiang-Nanpanjiang Basin,southwestem Guizhou Province are commonly hosted by the same fold crests that commonly contain a remarkable amount of organic material. The total organic carbon (TOC) contents of the ores and host rocks are usually less than 1%. The reflectance of vitrinite and pyrobitumen in the ores and the host rocks ranges from 1.5% to 4.5%, often in the range of 2% to 3%. In the Lannigou deposit, the reflectance of vitrinite and pyrobitumen in the ores is usually somewhat higher than those within the host rocks, indicating a hydrothermal impact on the organic matter in the altered host rocks. On the contrary, the estimated maximum paleotemperatures of the Getang and Zimudang deposits are higher than the homogenization temperatures of the fluid inclusions in the ores, signifying that the organic matter maturation predated Au mineralization. No correlation between the organic matter contents and Au concentrations were recognized in the ores.However, the most striking observation is that there is a positive correlation between the $2 (a parameter of Rock-Eval analysis), Au and As contents of the ores in the Lannigou deposit. Organic matter maturation and migration is apparent from the TOC vs. HCI diagram. Furthermore, group analysis of the dichloromethane extractable organic component of the ores and host rocks shows that the maturation degree of the organic matter in the ores is slightly higher than that of the host rocks in the Lannigou gold deposit. However, the compositions of their alkanes, steranes and terpenes, which serve as biomarkers, are quite similar; this suggests that the organic matter found in the ores and host rocks has a common marine source. Organic matter probably contributed to the preconcentration of Au in the host rocks. Hydrocarbons in the system,on the other hand, clearly contributed to the emplacement of the gold mineralization through thermal sulfate reduction.Organic matter in the solution might have increased the potential of the hydrothermal solution to transport Au.     

Some aspects of excellent marine source rock formation:implications on enrichment regularity of organic matter in continental margin basins

Through the analysis of ocean organisms, the distribution characteristics and enrichment of organic matters in modern marine sediments and ancient marine strata, this paper shows that the main factors influencing the formation of excellent marine source rocks are the paleoclimate, biologic productivity, terrestrial organic matter, oxidation–reduction environment, sedimentation rate, and the type of the basin. In addition to those factors,high biologic productivity or high content of terrestrial organic matter input is a requirement for the enrichment of the organic matter in a marine environment. Reducing environment was favorable for organic matter accumulation and preservation in depositing and early diagenesis stage, which is an important element for the formation of high-quality marine source rocks. Paleoclimate also influences the marine source rocks formation, as humid subtropical and tropical climates are the most favorable regimes for the formation of marine source rocks. Wind transports some vascular plant materials into the marine environment. Furthermore, upwellings driven by steady wind can cause high biologic productivity, thus formingorganic-C-rich mud. Suitable sedimentation rate is beneficial for marine organic matter accumulation. Moreover, the type of the basin also plays an important role in the development of marine source rocks. Silled basins with a positive water balance often act as nutrient traps, thus enhancing both productivity and organic matter preservations, while in open oceans, organic matter enrichment in sediments has just been found in the oxygen minimum layers.     

Organic Geochemistry Characteristics in Ores and Host Rocks from Qixiashan Lead-Zinc Deposit, Nanjing, China

Organic matter, associated with ores, host rocks, ore source rocks and present in fluid inclusions in the Qixiashan lead-zinc polymetailic deposit hosted in Upper Carboniferous dolomites and limestones in East China, was systematically analyzed using Fourier transform infrared spectroscopy, gas chromatography (GC), GC/mass spectrometry and proton-induced X-ray emission. The biomarker ratios of nC21^--/n22^ -alkanes, C23-tricydic/C30-hopane and the tricyclic terpane parameters induding C21/C23, C19-10/C21-29 and C19-25/C26-29 can effectively discriminate ores from host rocks. Extractable organic matter present in fluid inclusions displays similariUes to those enclosed in the ore source rocks in the biomarker ratios, suggesting that a proportion of orphic matter was introduced into the deposit from the ore source strata. The presence of copper and zinc in stage Ⅱ pyrobitumen indicates that some metals may have been transported by an organic fluid or removed from an aqueous fluid by organic matter.     

Metallogenic Mechanism of the Tianbaoshan Pb—Zn Deposit,Sichuan

The Tianbaoshan Pb-Zn deposit in Sichuan Province,exhibiting open-space-filling and /or replacement textures,occurs as being of vine style in the Sinian(Late Proterozoic) carbonate rocks,and is simple in ore composition.A systematic study of lead isotope and rareearth elements reveals that the ore-forming materials were derived from multiple sources.The ultimate source of the sulfur in all stages in seawater sulfate but the reducing mechanisms are different,The carbon was derved from marine carbonate and organic matter,The ore-forming fluid,meteoric in origin,belongs to a Ca^2 -Mg^2 -Cl^--Hco3^- type of weak acidic to alkalic solutions with a salinity of about 5wt% NaCl.The ore was formed at the depth of about 1 km from 150 to 250℃ during the main stage of ore deposition.The heated meteoric water,after extracting ore materials from wall rocks,evolved into ore-forming solution with a low salinity, in which metals were trasported as chloride complexes such as PbCl,ZnCl and ZnCl.The metal-bearing solution moved upward along deep faults to low-pressure zones,where the metal ions reacted with reduced sulfur and were precipitated as sulfied minerals.The textures of the minerals were controlled by the rate at which the reduced sulfur was supplied.     

Influences of the Basin Brines on Hydrocarbons of the Anthracosia Shales from Southwestern Poland

Previous studies have shown that the oxidizing brines from the Early Permian Rotliegende sequence have influences on the organic matter of Kupferschiefer. However, inside the Rotliegende sequence there are two other black shales: the Lower and Upper Antracosia shales, which have not been studied as much in detail as in Kupferschiefer. In the present study 12 samples from the Lower and Upper Antracosia shales were analyzed by organic geochemical methods in order to clarify the influences of the oxidizing brines on organic matter. The results indicate that the organic matter of the samples from the Upper Antracosia shale and the bottom of the Lower Antracosia shale was oxidized under the influences of the oxidizing brines. The oxidation resulted in a depletion of saturated hydrocarbons and the alky Is of the aromatic compounds.     

Mineralization and Ore-controlling Implications of Low-angle Faults

Low-angle faults include those occurring in thrust-nappe structures in a compressive setting and the detachment of metamorphic core complexes in an extensional setting. All low-angle faults have their own particularities. The low-angle fault plays an important role in controlling over some endogenetic metallic ore deposits. Based on studies of the Xiaoban gold deposit, Xinzhou gold deposit, and Longfengchang polymetallic ore deposit, and comparisons with other mines, the authors conclude the ore-controlling implications of low-angle faults as follows. (1) Because of high temperature and high pressure, as well as strong ductile deformation, the internal energy of the elements rises in the large-scale deep ductile low-angle faults, which causes the elements to activate and differentiate from the source rocks, forming ore-bearing hydrothermal solution, and bring mineralization to happen. (2) When rising from depths and flowing along the low-angle faults, the ore-bearing hydrothermal solution will alter and     

某地下寒武统含镍钼多元素黑色岩系的岩石学及地球化学特点

Studies of sedimentology, ore micrascopy and geochemistry have been carried out on a Ni- Mo- multi-element-bearing black shales of the Lower Cambrian Niutitang Formation. Chemical analyses, electronprobe analyses, X-ray powder diffraction methods,optical, spectrographic and DTA techniques and electron photomicrographs arc also used in the research. Conclusive information has been obtained about the mode of occurrence of nickel,molybdenum and other elements, about their distribution within the Niutitang Formation, and about their concentrations in various types of sedimentary rocks. A preliminary discussion is also given to the depositional sequence of the Niutitang Formation as well as to thc controlling factors for the enrichment of these elements. Nickel and molybdenum are mainly enriched in thin-bedded and leuticular bodies within which Pt, Pd, Os, Au, TR, Se, T1, Cu, Zn etc. are also concentrated, showing a complex assemblage of elements and various occurrences. Major ore minerals are vaesite, polydymite, millerite, gersdorffite, jordisite, pyrite, chalcopyrite, tennantite.sphalerite. Gold and silver occur as Ag-bearing native gold. Barium is presented as barite. Selenium and thallium are considered to be related to pyrite. Rarc earths, on the other hand, are concentrated in phophorite and phosphorous nodules. The black shales have undergone sedimentation-diagenesis, epigenetie alteration and secondary oxidation. The depositional environment was strongly reducing. Organic materials played a definite part in the formation of siliceous matter, pyrite and some other sulfides. Nickel-molybdenum-multi-element-rich beds are found in the transitional zone from phosphorite to hlae.k siliceous rocks. It is believed that changes in depositional environment are the principal factors controlling the enrichment of the multi-element.     

The Cenomanian—Turonian Anoxic Event in Southern Tibet：A Study of Organic Geochemistry

The Cenomanian-Turonian oceanic anoxic event(C/T OAE) is developed in southern Tibet.Organic geochemical study of the Cenomanian-Turonian sediments from the Gamba and Tingri aress shows that the mid-Cretaceous black shales in southern Tibet are enriched in organic carbon.Te molecular analyses of organic matter indicate marine organic matter was derived from algae and bacteria.In the Gamba area,the organic matter is characterized by abundant tricyclic terpanes and pregane,which are predominant in 191 and 217 mass chromatograms,respectively,Pristane/phytane(Pr/Ph)ratios in the C/T OAE sediments are less than 1, demonstrating the domination of phytane.The presence of carotane can be regarded as a special biomarker indicating oxygen depletion in the C/T OAE sediments in the Tethyan Himalayas.In anoxic sediments,β-carotane and γ－carotane are very abundant.The β-and γ-carotane ratios relative to nC17 in the Cenomanian-Turonian anoxic sediments vary from 32.28-42.87and 5.10-11.01.     

Metallogeny of the Lannigou Sedimentary Rock-hosted Disseminated Gold Deposit in Southwestern Guizhou Province, China

The Lannigou deposit is a large-sized sedimentary rock-hosted disseminated gold （SRHDG） deposit located in the Youjiang Basin. It is hosted by the Middle Triassic turbidite. Wall rock alterations, including silicification, pyritization, arsenopyritization, carbonatization and argillization, commonly occur along fractures. PGE study demonstrates that either Permian basalts or Triassic ultrabasic intrnsives are unlikely to be the main source of gold mineralization. Coupled with the lack of other nmgmatic activity in the vicinity of the mining area, an amagmatic origin is proposed. Organic matter compositions and GC-MS analysis of the ores and host rocks show that the organics in the ores and the host rocks have a common source; the organic matter in the ores was mainly indigenous. The positive correlation between S2 and Au contents, along with the common occurrence of organic inclusions, suggest involvement of organic matter in the ore-forming process in terms of promoting Au leaching from the source rocks, making colloidal Au migration possible, as well as hydrocarbon reduction of sulphate. Geological and geochemical characteristics of the Lannigou deposit suggest that it was formed through circulation of meteoric water and probably less importantly organic bearing formation water driven by high geothermal gradient caused by late Yanshanian extension, which leached Au from the source bed, and then migrated as Au-bisnlfides and colloidal Au, culminating in deposition by reduction-adsorption and surface complexation of gold onto the growth surface of arsenlan pyrite.     

Study of the Factors Affecting the Abundance of Organic Matter in Jurassic Carbonate Rocks in Qiangtang Basin, Tibet

Field and laboratory analyses of carbonate rock samples from the Qiangtang Basin,Tibet, indicate that carbonate source rocks are mainly developed in the Middle Jurassic Xiali Formation and Upper Jurassic Suowa Formation. Comprehensive studies showed that the Suowa Formation carbonate source rocks have a favorable hydrocarbon-generating potential. The abundance of organic matter in the carbonate rocks is controlled mainly by sedimentary environment and inorganic compounds in the rocks, which is higher in the restricted platform facies than in the open platform facies. Organic carbon contents decrease with increasing CaO contents in the source rocks.     

AN OIL SHALE SITE IN EL LAJJUN AREA, CENTRAL JORDAN: A VES RESISTIVITY SURVEY

1. IntroductionThe Geophysics Division of the Natural Resources Authority (NRA), Jordan, conducts field site investigation utilizing resistivity-sounding method at El Lajjun area where oil shale deposit has been found. The term "oil shale" is used worldwide as an indicator of sedimentary rocks, which contain organic matter, mainly kerogen. Jordanian oil shales are kerogen-rich, bituminous and argillaceous limestone. Other minerals and rare earth elements and metals (e. g., sulfur, vanadiu…     

Sulphur and Lead Isotope Compositions of the Dajiangping Deposit in Western Guangdong Province

The Dajiangping pyrite deposit located in the middle sector of the Yunkai uplift in western Guangdong is a stratiform sulphide deposit occurring in Sinian marine clastic and fine clastic rocks. The formation of the deposit was related to submarine exhalation and hot brine deposition. A part of it was reformed by late-stage hydrothermal solution. The δ34S values of pyrite vary from - 25.55‰ to +21.07‰, which are inversely proportional to the content of organic carbon in ore and pyrite. Passing from striped fine-grained pyrite ore to massive coarse-grained pyrite ore, i.e. from south to north, the sulphur isotopic composition changes from the light sulphur-enriched one to the heavy sulphur-enriched one. The lead isotopic composition of striped ore is consistent with that of the country rocks of orebodies and the lead is radiogenic lead derived from the upper crust. The lead isotopic composition of massive ore is relatively homogeneous and its 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios are a bit lo     

Lower Cambrian Black Rock Series and Associated Stratiform Deposits in Southern China

Widespread in more than ten provinces of southern China are the Lower Cambrian black argillaceous-arenaceous rock series consisting of black carbonaceous shales,black carbonaceousargillo-siliceous rocks,black carbonaceous silicolite and black silicolite and black carbonaceous argillaceous siltstone.The Ni,Mo,V,Cu,U,Ba,Ag,P contents of these series are usually several to tens of times higher than their average values in shales.As viewed from lithological sequence,element association and evolution,these black series can be diveided into two types.There occur a variety of deposits in the black rock series,such as phosphorite deposits,Ni-Mo-V polymetal deposits and “Stone coal“ seams.According to ore composition,texture and structure,the phosphorite deposits fall into three types,i.e.,thick-bedded,lenticular and nodular,The Ni-Mo-V polymetal deposits,V deposits and reworked sedimentary CU-U-Cd polymetal deposits in terms of their element assiciation and ore genesis.As for the stratiform deposits in the black rock series,three mineralization stages have been recognized,i.e.,the formation of phosphorite deposits,of Ni-Mo polymetal deposits and of V-Cu-U-Cd polymetal deposits as well as of “:stone coal“ seams.Evidence strongly suggests that lower organisms have played an important role in mineralization. Our studies indicate that the Lower Cambrian black argillaceous-arenaceous rock series in southern China and their associated stratiform deposits occur generally in the basal parts of a big sedimentary cycle,i.e.,the initial period of a transgression,or in the fine detrital-siliceous formation between two carbonate formatons,formed in a humid climatic zone between two arid ones.As for the environment of deposition,it is suggested that the Lower Cambrian black argillaceous-arenaceous rock series and associated stratiform deposits(excluding thick-bedded phosphorite deposits)were formed mainly in a restricted and poorly-fed sea basin of stagnant shallow water containing abundant lower or ganisms and organic matter under statically hydrodynamic conditions.     

Genesis of the Dalingzi Pb-Zn Deposit in the Western Margin of Yangtze Plate: Constraints from Fluid Inclusions and Isotopic EvidenceEI北大核心CSCD

The Daliangzi Pb-Zn deposit is a large deposit hosted in the Sinian Dengying Formation dolostone, located in the Sichuan-Yunnan-Guizhou ore concentration area. Ore minerals are mianly sphalerite, galena, and gangue minerals consist of dolomite, quartz and calcite. The metallogenic stages may be divided into sphalerite-pyrite-carbon stage, sphalerite-galena stage and galena-chalcopyrite-carbonate stage. The ore-forming fluid is basin brine, which is characterized by medium-low temperature of 117.5 ℃ to 320.3 ℃ and medium salinity of 5.11% NaCleqv to 18.96% NaCleqv, moreover, the abundant CH4 and pitch in the fluid inclusions indicate that the participation of organic matter in the mineralization. The δ13CV-PDB and δ18OSMOW values of the Dengying Formation dolostone are similar to that of marine carbonate, revealing that the dolostone belongs to marine carbonate. Both the δ13CV-PDB and δ18OSMOW values of hydrothermal calcites are lower than that of the Dengying Formation dolostone, which may result from dissolution of the Dengying Formation dolostone. The δ34S values of ore minerals are mainly in the range of 9.8‰-20.8‰, indicating the sulfur may come from thermochemical reduction of marine sulfate in the Dengying Formation. The 207Pb/204Pb versus 206Pb/204Pb diagram manifests that Pb is crustal origin, and likely comes mainly from the wall rocks and less from the basement. (87Sr/86Sr)i ratios of sphalerites and hydrothermal calcite are higher than that of the Dengying Formation dolostone, indicating that the ore-forming fluid flew through the basement. In conclusion, the ore-forming fluid was basin brine, which extracted the metallogenic materials, Pb and Zn, from the basement and wall rocks. When the ore-forming fluid reached the "black fractured zones", carbonized tectonic breccia zone, S2- was produced by the thermochemical reduction reaction under the influence of the organic matter, and interaction between the S2- and Pb2+, Zn2+, resulted in the precipitation of ore metals. © 2018, Science Press. All right reserved.     

Comparative Study of Gacun and Youre Silver–Lead–Zinc–Copper Deposits in Sichuan, SW China, and their Mineralization Significance

The large Gacun silver–lead–zinc–copper deposit in Sichuan Province is one of the largest volcanogenic massive sulfide(VMS) deposits in China. The deposit consists of western and central ore bodies, which form a vein–stockwork mineralization system corresponding to hydrothermal channels, and eastern ore bodies, which form an exhalative chemical sedimentary system derived from a brine pool in a submarine basin. The Youre lead–zinc deposit, which is currently under exploration and lies adjacent to the southern part of the Gacun deposit, is characterized by intense silicification and vein–stockwork structures and consists of massive silicified rhyolitic volcanics, banded rhyolitic tuff, and phyllitic sericite tuff. From a comparison of their ore-bearing horizons, the Gacun and Youre deposits have a continuous and stable hanging wall(calcareous slate and overlying andesite) and foot wall(rhyolite–dacite breccia and agglomerate), and the lithologic sequence includes lower intermediate to felsic rocks and upper felsic rocks. Thus, the Youre deposit, which comprises relatively thinly layered low–grade ore, is regarded as forming a southward extension of the Gacun deposit. A further comparison of the structures of the ore-bearing belts between the two deposits suggests that the Youre ore bodies are similar to the western ore bodies of the Gacun deposit. Moreover, the characteristics of fluid inclusions and stable isotopes in the Youre deposit are also similar to those of the western ore bodies of the Gacun deposit. Genetic models of the deposits are proposed for the Gacun–Youre ore district, and massive concealed ore bodies may occcur in the Youre deposit at depths that are similar to those of the eastern ore bodies of the Gacun deposit.     

Geological Conditions and Prospect Forecast of Shale Gas Formation in Qiangtang Basin,Qinghai-Tibet Plateau

The presence of shale gas has been confirmed in almost every marine shale distribution area in North America.Formation conditions of shale gas in China are the most favorable for marine,organic-rich shale as well.But there has been little research focusing on shale gas in Qiangtang Basin,Qinghai-Tibet Plateau,where a lot of Mesozoic marine shale formations developed.Based on the survey results of petroleum geology and comprehensive test analysis data for Qinghai-Tibet Plateau,for the first time,this paper discusses characteristics of sedimentary development,thickness distribution,geochemistry,reservoir and burial depth of organic-rich shale,and geological conditions for shale gas formation in Qiangtang Basin.There are four sets of marine shale strata in Qiangtang Basin including Upper Triassic Xiaochaka Formation （T3x）,Middle Jurassic Buqu Formation （J2b）,Xiali Formation （J2x） and Upper Jurassic Suowa Formation （J3s）,the sedimentary types of which are mainly bathyal-basin facies,open platform-platform margin slope facies,lagoon and tidal-fiat facies,as well as delta facies.By comparing it with the indicators of gas shale in the main U.S.basins,it was found that the four marine shale formations in Qiangtang Basin constitute a multi-layer distribution of organic-rich shale,featuring a high degree of thickness and low abundance of organic matter,high thermal evolution maturity,many kinds of brittle minerals,an equivalent content of quartz and clay minerals,a high content of feldspar and low porosity,which provide basic conditions for an accumulation of shale gas resources.Xiaochaka Formation shale is widely distributed,with big thickness and the best gas generating indicators.It is the main gas source layer.Xiali Formation shale is of intermediate thickness and coverage area,with relatively good gas generating indicators and moderate gas formation potential.Buqu Formation shale and Suowa Formation shale are of relatively large thickness,and covering a small area,with poor gas generating indicators,and limited gas formation potential.The shale gas geological resources and technically recoverable resources were estimated by using geologic analogy method,and the prospective areas and potentially favorable areas for Mesozoic marine shale gas in Qiangtang Basin are forecast and analyzed.It is relatively favorable in a tectonic setting and indication of oil and gas,shale maturity,sedimentary thickness and gypsum-salt beds,and in terms of mineral association for shale gas accumulation.But the challenge lies in overcoming the harsh natural conditions which contributes to great difficulties in ground engineering and exploration,and high exploration costs.     

Simulating experiment on the enrichment of precious metals in Lower Cambrian black shale series of Hunan and Guizhou provinces

Adsorption experiments were made at room temperature and neutral pH value on different types of min-erals associated with the Lower Cambrian black shale series polymetallic layers in Hunan and Guizhou provinces on nanometer-sized Pt colloids and PtCl42--bearing ionic solutions with an attempt to constrain the relationship between the different types of minerals in the polymetallic layers and the enrichment of platinum group elements (PGEs). Experimental results showed that the different types of minerals show strong selectivity to the adsorption of nano-meter-sized Pt colloids and PtCl42--bearing ionic solutions. Metallic sulfides, organic matter and clay minerals are the strong adsorbents of PGEs, while quartz, albite, muscovite and other silicate minerals show a week adsorbility to both of them. This phenomenon is well consistent with the geological fact that metallic sulfides, organic matter and clay minerals in the polymetallic layers of the black shale series are the major carrier minerals of PGEs, giving a thorough explanation to the mechanism of enrichment of previous metal elements. Adsorption may be a principal mechanism of enrichment of precious metal elements under lower temperature conditions. The presence of the aforementioned strong adsorbents is the good geochemical barriers for the enrichment of PGEs.     

Research on the Eco-Geochemical Effects of Black Shales in Pingli County,Shaanxi

This paper presents the results of eco-geochemical research on black rock series enriched in metallic elements in Pingli County,Shaanxi Province,which lies at the northern margin of the Yangtze Platform.There is a suite of bone coal-bearing black carbonaceous rocks in the Cambrian Donghe Formation throughout the region.Soils in Pingli contain high metallic elements derived from the bone coal and carbonaceous rocks.Edible plants growing in the soils contain high Se,Cu and Mo.Two case studies are documented.One is a black shale area with bone coal and Se enrichment,and the other is a black shale area with bone coal mine and copper mineralization.Eco-geochemical effects of metallic element-rich black shales on plants are reported in this paper.