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1.
Mining and smelting activities are the main causes for the increasing pollution of heavy metals in soil, Water body and stream sediment. An environmental geochemical investiga-tion was carried out in and around the Panzhihua mining and smelting area to determine the ex-tent of chemical contamination in soil and sediment. The main objective of this study was to in-vestigate the environmental geochemistry of Ti, V, Cr, Mn, Cu, Pb, Zn and As in soil andsediment and to assess the degree of pollution in the study area. The data of heavy metal con-centrations reveal that soils and sediments in the area have been slightly contaminated. Geo-chemical maps of Igeo of each heavy metal show that the contaminated sites are located in V-Ti-magnetite sloping and smelting, gangues dam. The pollution sources of the selected elementscome mainly from dusts resultant from mining activities and other three-waste-effluents. The areaneeds to be monitored regularly for trace metal, especially heavy metal enrichment.  相似文献   

2.
Yerevan-the capital city of Armenia used to be a highly developed industrial center whose enterprises were integrated into the former USSR＇s industrial network. For this, the USSR disintegration entailed stagnation of most plants. Lately, some of them resumed operating, new enterprises were created, conditioning qualitative and structural changes in the city＇s industrial complex. Naturally,first of all, such changes manifest themselves in the extent of the impact of operating plants upon the environment and the air basin. This atmo-geochemical research was performed through studying natural depositing medium - snow cover, as the composition of its insoluble fraction is identical to that of solid constituent of air pollutants. The solid phase was analyzed through the method of quantitative spectral analysis for a wide set of heavy metals. Based on the data on heavy metal contents in separate samples, specialized geochemical maps of the city＇s territory were produced applying GIS ArcView 3.2 a. These initial data allow to calculate in-day dust load per square kilometer -38.3 kg/sq, km＊day, respectively, for the whole of the city＇s territory （225 sq. km） -8.6 tons. Data on element contents in dust allow to calculate the load of separate elements throughout the city landscape; so in-day load of Zn is 2.3 kg, Cu 1.1 kg. The determined contents of heavy metals are standardized by the element background and the following ranked geochemical series of heavy metal contents in ambient dust throughout the city was made up： Mo-Ag-Sn-Zn-Ni-Cu-Cr-Pb. The maps clearly reflect the morphology and extent of pollution zones and the structure of pollution. To characterize complex pollution, we have calculated a Summary Index of Pollution （SIP） that represents the sum of heavy metal contents in samples standardized by the background.  相似文献   

3.
Heavy metals in different environmental compartments can be hazardous to ecosystems. Budgets of Cd, Pb and Zn in small ecosystems of the Shubra E1-Kheima area in Egypt are presented. The budgets are not in steady state because they change with time. So the concentrations of the metals are a function of time. The critical loads of heavy metals to soils can be calculated from an inventory of inputs and outputs of the trace components in the catchment area.Critical time is an important parameter for critical load evaluation because it can indicate which of the heavy metals may be the most acute threat to the soils. Egyptian soil in the Shubra ElKheima area seems to be in danger of heavy metal pollution by Zn, Cd and Pb. The calculated critical loads and their exceedances are approximate indicators of the hazards in the soil system.The critical time is a warning signal to initiate an environmental evaluation of possible pollution hazards.  相似文献   

4.
It has been found that stream waters were severely contaminated with wastes from a long-time smelting factory in Hezhang, Guizhou, China. The main sources of contamination are the smelting wastes stored in the open air and abandoned in the vicinity of stream. A method of lead isotope was adopted in order to identify relations between tailings and water contamination. Representative samples of tailings and stream sediments were collected. Mineralogical characterizations were conducted using XRD and TEM/SEM, while acid digestion was carried out for determining metal contents. BCR sequential leaching tests were performed in order to assess metal mobility. The tremendous ‘actual＇ and ‘potential＇ mobility of heavy metals indicates that the smelting waste and stream sediments present a considerable threat to the environment. Besides the chemical remobilization of heavy metals from the sediments and the reworking of riverbed sediments act as a secondary source of pollution. Also groundwater and stream water were sampled in specific locations and were measured.  相似文献   

5.
Heavy metal contamination in the sediment of the Second Songhua River   总被引：1，自引：0，他引：1  
The Second Songhua River was subjected to a large amount of untreated effluent from petrochemical industries in Jilin City in the 1960s to the 1970s. The objectives of this study were to investigate the mercury and other heavy metal contamination in the sediment of the river. The river bottom sediment was sampled from the river segment between Jilin City to Haerbin City in 2005. Total concentrations of Hg, Cd, Cu, Cr, Pb, Zn, Ni, As, Sc, and major cations （A1, Fe, Mg, Ca, K, Na） in the sediment were measured by atomic fluorescence spectrometer, ICP-MS, and ICP-OES, respectively, following digestion with various acids. We found the concentrations of most elements in the uncontaminated sediment were significantly correlated to those of Sc.  相似文献   

6.
This study focused on the geochemical distribution patterns and ecological effects of Cd and other heavy metals such as As, Hg, Cr, Cu, Ni, Pb, and Zn in rock, soil, water, sediment and crops in the area of the Three-Gorges Reservoir within Chongqing, and aimed at the protection of ecological environment and rational application of the local lands. This study found that the metals of Cd, Hg and Pb presented pollution in the surface environment along the Yangtze River, that is Cd〉Hg〉Pb （Cu）〉Zn〉As〉Ni〉Cr. The pollution of Cd in sediment was mainly attributable to the regional black shales, and partly to the urban sewage and garbage. The geochemical modes of metals in the sediment varied. Cr, Hg, Ni, and Pb mainly existed as residues, and Cd as carbonate. Cd exited as a high proportion in the modes of ion-exchange, carbonate, and iron-manganese oxidation, up to 63 percent. The contents of heavy metals in soiland sediment were correlated to the host clay minerals, such as illite, montmorillonite, kaolinite and chlorite. It is shown that Cd was transported with clay minerals in the Yangtze River over long distance and formed the regional anomaly. In the abnormal area of Jianping in Wushan County, higher Cd contents are reported in the local crops and local villagers＇ hairs than from the background areas.  相似文献   

7.
Perfluorinated organic compounds(PFOCs) are emerging persistent organic pollutants(POPs) widely distributed in the environment,wildlife and human.We studied the toxicology of perfluorooctane sulfonate(PFOS) and perfluorooctanoic acid(PFOA) on immunotoxicity and hepatotoxicity in primarily cultured hepatocytes of freshwater tilapia(Oreochromis niloticus).Cultured hepatocytes were exposed to PFOS or PFOA(0,10,20 and 30 mg/L) for 24,48,72,96,120 and 144 hours,respectively.Oral doses of these compounds that induce significantly detectable immunotoxicity and hepatotoxicity were employed in the study.In response to PFOS,the leukocytes,B cells,granulocytes,and macrophages among the isolation of intrahepatic immune cells(IHIC) from PFOS-treated tilapia produced significant levels of immune cells compared with that of the control group.The numbers of leukocytes,B cells,granulocytes,and macrophages for PFOS-treated tilapia increased with the incremental exposure concentration.Moreover,similar to the findings in PFOA toxicity effects,the erythropoietin levels in tilapia increased with the increase of the PFOS and PFOA concentrations.The lowest doses(10 mg/L) of PFOS exposure led to a marked inhibition in the hepatocyte viability in tilapia.Similarly,tilapia exposed to PFOA demonstrated a similar pattern,and a dose-dependent decrease in the hepatocyte viability was observed in the following treatment of PFOA.In the 72 h exposures,ethoxy-resorufin-O-deethylase(EROD) activity was significantly induced with the increase concentrations in tilapia liver(p<0.05).Tilapia showed a strong EROD induction in livers,and significantly difference in EROD activity was observed between control,PFOS and PFOA-exposed tilapias.The liver glycogen content showed that PFOS and PFOA exposure caused significant changes in the liver glycogen content,which depended on the duration of exposure.And it appeared that the decrease in blood glucose level during the acclimation was followed by significant increase in liver glycogen content in tilapia.  相似文献   

8.
Heavy metal contamination has attracted huge concern due to its toxicity, abundance and persistence in the environment, and subsequent accumulation in soil, sediment and water. Mining is one of the most important sources of heavy metals in the environment. Mining-milling operations and disposal of tailings （the finely ground remains of milled ores） in addition to smelting and metal refining provide significant sources of pollution. Mining and mineral processing in the Dexing region of China have been carried out for over forty years and have contaminated the soils with heavy metals, Many studies were conducted to assess and establish the extent of heavy metal contamination in the soils due to mining. The aim of this work was to assess the environmental impact of mining on soils in the Dexing region and to identify the main factors involved in heavy metals dispersion. A 4800 km^2 study area was assessed with respect to its heavy metals on the basis of the current guideline values. In order to assess the extent of heavy metals contamination resulting from past mining activities in the Dexing region, 919 soil samples were collected and analyzed for As, Hg, Cd, Cr, Zn, Cu and Pb, Heavy metals levels were determined using inductively couple plasma-atomic emission spectrometry and X-ray fluorescence spectrometry. Results of soil samples reported concentrations between 1.790-899 mg/kg for As, 0.034-4.980 mg/kg for Hg, 0.043-8.330 mg/kg for Cd, 10-666 mg/kg for Cr, 25-18500 mg/kg for Zn, 6-1825 mg/kg for Cu, and 16-1312 mg/kg for Pb, respectively. The maximum values of As, Hg, Cd, Cr, Zn, Cu and Pb concentration in soils were up to 60, 33, 41, 7, 185, 52 and 37 times higher than the tolerable level, respectively. Meanwhile, the single-factor pollution index and Nemerow pollution index were used to assess the environment quality of heavy metals contamination.  相似文献   

9.
Along with the rapid development of science and technology, natural matter and energy are further exploited and used. The pollution imposed on nature has also sharply increased. Only do we know the pollution history, can we make a correct appraisal of local environment, get the hold of the main cause of environmental pollution, and then take the effective measures to control the environment？ The evolution of heavy metal concentrations with time in the soil environment in the southern suburbs of Beijing were studied by using annual growth rings of trees. The absorption of 12 elements by different tree species in the same soil type was studied according to their absorption coefficients. The study indicated the differences in adsorption of elements by different species of trees. The adsorption coefficients of the elements Zn, Cd and P are higher. The correlations of nine elements （Na, K, Cu, Zn, As, Sr, Cd, Ba and Pb） in growth rings of poplar trees and those in soils near their roots show that the element contents in growth rings have a positive correlation with the contents in soils near the roots. Based on the logarithmic linear correlation model, the evolution of the contents of the elements Cu, Zn, As, Cd, Ba and Pb in soils from 1982 to 2004 was deduced. The trees have the characters of confirming year precisely, long life and widespread distribution. They are the ideal objects of study on environmental pollution changes. At present, research in China in this aspect is less, and the field of research is expected to further expand. This method can be used to provide richer and more scientific information on the history of environmental pollution and changes during modem urbanization in the past few decades and predicting the evolutionary trend of pollution change.  相似文献   

10.
A total of 63 soil samples from 3 different soil profiles （urban, suburban and industrial areas） in major towns in the east coast of Peninsular Malaysia were analyzed for the total concentrations of Cu, Zn, Pb, Ni and Cr. The soil samples were subjected to acid digestion and the concentrations of total metals extracted were measured or flame atomic absorption spectrometry and inductively coupled plasma - atomic emission spectrometry. According to the result of this study, Pb and Zn concentrations in urban soils are much higher than those of industrial and suburban soils. Total concentrations of Cu and Cr in industrial soil samples are high compared to other two soil profiles and Ni concentrations in the suburban area are slightly higher those of urban and industrial soils. Since Malaysia has not yet to come up with her own soil maximum allowable limit, the heavy metal concentrations were compared with the Dutch maximum allowable limit. The results indicated that the median of heavy metals values in the three different soil profiles is still below the Dutch system limit. From the maximum allowable value obtained from the Dutch system, a contamination/pollution （C/p） index for each site was calculated for the set of these five heavy metals. An advantage of using this method is to make a differentiation between pollution （C/p〉1） and contamination （C/p〈1） status in soils as well as being able to characterize each status into 5 different categories （slight, moderate, severe, very severe and excessive）.  相似文献   

11.
The Ni-Mo-PGE polymetallic mineralization of the Lower Cambrian black shales locate in Zunyi, South China and contain abundant noble metals such as Ag, Au and PGE, and especially Ag with average concentration of 64×10-6. The occurrence modes of Ag have been investigated using methods of selective chemical dissolution and transmission electron microscopy. The results demonstrate that the occurrence modes of Ag are complex and diversiform. It might be associated with clay minerals, organic matter, sulfides and also occurred as native silver and sulfides with nanometer in size. Combined with results of previous studies, we suggest that the sulfides, clay minerals and organic matter which hosted in the Ni-Mo-PGE polymetallic ores of black shales can play the roles of important reduction and adsorption geochemical barriers for the enrichment and distribution of silver. This study further implies that the selective chemical dissolution and transmission electron microscopy may pave the way to study the occurrence modes of other noble metals in black shales.  相似文献   

12.
The present study investigates the hydrogeochemical characteristics of groundwater quality in Agas- theeswaram taluk of Kanyakumari district, Tamil Nadu, India. A total of 69 groundwater samples were collected during pre- and post-monsoon periods of 2011-2012. The groundwater quality assessment has been carried out by evaluating the physicochemical parameters such as pH, EC, TDS, HCO3, Cl, SO42-, Ca2＋, Mg2＋, Na＋ and K＋ for both the seasons. Based on these parameters, groundwater has been assessed in favor of its suitability for drinking and irrigation purpose. Dominant cations for both the seasons are in the order of Na＋〉 Ca2＋〉 Mg2＋ 〉 K＋ while the dominant anions for post monsoon and pre monsoon have the trends of CI 〉 HCO3 〉 SO42- and HCO3- 〉 CI 〉 SO42-, respectively. Analytical results observed from various indices reveal that the groundwater quality is fairly good in some places. Analytical results of few samples show that they are severely polluted and incidentally found to be near the coasts, estuaries and salt pans in the study area. The Gibbs plot indicates that the majority of groundwater samples fall in rock dominant region, which indicates rock water interaction in the study area. The United States salinity （USSL） diagram shows that the groundwater is free from sodium hazards but the salinity hazard varies from low to very high throughout the study area. This reveals that the groundwater is moderately suitable for agricultural activities. The observed chemical variations in pre-monsoon and post-monsoon seasons may be the effect to rock-water interactions, ion-exchange reactions, and runoff of fertilizers from the surrounding agricultural lands.  相似文献   

13.
The present research deals with the geochemical characteristics of the Holocene sediments from Alamdanga area, Chuadanga district, Bangladesh. Main goals of the study are to delineate source rock characteristics, degree of chemical weathering and sorting processes and behavior of redox conditions during deposition of the sediments. Geochemical characteristics of the sediments show comparatively a wide variation in accordance with stratigraphy in their major element contents （e.g. SiO2 69.46-82.13, A1203 2.28-8.88 in wt%）, reflecting the distinctive provenance and in part an unstable period in terms of tectonic activity. Geochemical classification of the sediments shows mostly sub-arkose with few sub-litharenites. Some major and trace elements display comprehensible correlation with A1203 confirming their possible hydraulic fraetionation. The chemical index of alteration （CIA＊）, W＊ index, index of compositional variability （ICV）, plagioclase index of alteration （PIA＊） values and the ratio of SIO2/Al2O3, suggest low degrees of chemical weathering in the source areas as well as immature to moderately mature the sediments. The sediments suggest semi-arid climatic trends within oxic deltaic depositional conditions during the Holocene, at 3-12 ka. Whole rock geochemistry and discrimination diagrams demonstrate the continental signature derivatives, which might have been derived from the felsic to intermediate igneous rocks （granitic plutonic rocks） as well as from quartzose sedimentary/metamorphic provenance. These typical sources are present in a vast region of the Himalayan belt and catchment areas of Ganges. The tectonic setting of the sediments demarcates typically passive margin with slightly continental arc system.  相似文献   

14.
Kuruqtagh block is the best area for Precambrian geology in Xinjiang Autonomous Region, NW China, since it exposed complete Precambrian lithology units. The study of this ancient base will deepen the understanding of the Precambrian evolution of the Tarim Basin. In this paper, we studied the petrology, geochemistry, zircon LA-ICPMS U-Pb chronology and zircon Hf isotope of Daxigou anorthosite （DA） which is located at the northem margin of Tarim craton and discussed the rock formation, tectonic and geological significance. Zircons from the intrusions display oscillatory zoning and high Th/U ratios （0.39-1.35）, implying their magmatic origin. Zircon LA-ICP-MS U-Pb dating results indicate that they formed during the Paleoproterozoic age with the weighted 2~6pb/238U average age of 1818~9 Ma, which is significantly different from former＇s Neoproterozoic age, and is co- incidentally identical with its associated syenite granite age within the error range. Studies on petrogeochemistry suggest that DA belongs to medium-sodium peraluminous alkaline type, rich in Pb, La, Th and LILE, and poor in HFSE （Gd, Nd, and Ta）. The chondrite-normalized REE pattern is slightly to the right form. The average Y~REE is 317.2~ 10-6; HREE show moderate fractionation [average LREE/HREE is 14.71, average （La/Yb）N is 24.77; average （LaJSm）N is 3.85, and average （Gd/Yb）y is 3.46]; and the 6Eu and 8Ce are not obvious. Their initial Hf isotope ratios and Hf two-stage model ages range from -6.6 to -4.43 and 2.63 to 2.74 Ga, respectively. Taken together, it is sug- gested that Daxigou anorthosite is a typical volcanic anorthosite and its primary magma could be contaminated by the partial melt Neoarchaean crust and mainly formed in the arc environment, which recoded the tectonic-magma activities response of the Tarim refers to the amalgamation of the supercontinent Columbia.  相似文献   

15.
A naturally selenium-accumulating Cardamine sp. is growing in Yutangba Selenium Mining Field, Enshi area, Hubei Province, China, where the geochemical environment is selenium-enriched and endemic selenosis ever occurred in humans. The present study investigated the characteristics of accumulation, speciation and quantity of selenium in Cardamine sp. with HPLC-ICP-MS. Results show that Cardamine sp. can accumulate Se at most 1427 mg/kg in seedling leaves. Even after the biomass incensement of growing up, the plant still could accumulate Se up to several hundred of mg/kg in concentration. Moreover, the biomass enrichment coefficient （BEC） of Se is exceedingly high, in the seedling leaves mostly, higher than 50 mg/kg; in the range of 43.7-68 mg/kg; and the lowest value is higher than 3 mg/kg in mature fronds. Se is present in the plant predominantly in form of SeCys2 with the highest concentration in seeds; up to 1081 mg/kg as Se. In contrast, SeCysz levels are low during early growth period; they are 136.1 mg/kg as Se in seedling fronds and 39.4 mg/kg as Se in mature fronds, respectively. SeMet concentration is comparatively low; 10.6 mg/kg as Se in seedling frond and 5.3 mg/kg as Se in half mature fronds, respectively. This indicates that Cardamine sp. is extremely efficient in extracting Se from soil and translocating it into its above-ground biomass. Therefore, Cardamine sp., found in Yutangba Se Mining Field may be a new Se hyperaccumulator. It is still uncertain whether the Se-accumulation or detoxification of Cardamine sp. happens through the pathway of SeCys methylated to form Se-methylselenoCys or through the formation of Se-carboxymethyl- selenohomocysteine. Indeed, further study should be carried out on the determination of more Se species to explain the high Se hyperaccumulation in Cardamine sp.  相似文献   

16.
The role of chloride ions in metal sulfides leaching has been well established by researchers, the complexation of chloride ions was considered to be the main effect of chloride ions. In this work, the complexation of chloride ions was neglected by addition of EDTA, a strong complexing agent. In this way, further study was conducted on the effect of chloride ions. The increase of chloride ions concentration from 0 to 2 mol/L, decreased the open circuit potential of pyrite from 264 to 91 mV. Unless otherwise stated, all potentials in this paper are based on the potential of saturated calomel electrode. At 600 mV, the increase of chloride ions concentration acceleraed pyrite oxidation; at 800 and 1000 mV, however, the increase of chloride ions concentration lowered pyrite oxidation rate, and the proportion of elemental sulfur was also decreased with increasing chloride ions concentration; when chloride ions concentration increased from 0 to 2 mol/L, the proportion of elemental sulfur decreased from 32% to 28.4% at 800 mV, and 7.1% to 2.4% at 1000 inV.  相似文献   

17.
The Ni-Cu-platinum group element sulfide ore deposits of the Kharaelakh Intrusion,Noril′sk Region,Siberia,represent a large concentration of sulfides associated with a small differentiated intrusion formed at the edge of the Siberian Craton in the roots of the Siberian Trap flood basalt.The deposit is associated with an intrusion that occupies a flanking periclinal structure adjacent to the Noril′sk-Kharaelakh Fault.The intrusion is strongly differentiated and comprises taxitic gabbrodolerites,picritic gabbrodolerites,and gabbrodolerites within the main body which in turn forms a chonolith within a sheet-like intrusion that extends laterally to form extensive undifferentiated sills of gabbrodolerite.The intrusion substantially replaces the stratigraphy of the country rocks,and although it appears to have exploited the axis of structures developed in response to transtension,the intrusion has created space by both mechanical dilation of stratigraphy and magmatic replacement of pre-existing sedimentary rocks.The frontal lobes of the main intrusion have complex apophyses of gabrodolerite on a range of scales that demonstrate replacement of the sedimentary rocks and link to the development of an extensive metamorphic halo in the country rocks.This halo is much narrower over the main body of the intrusion,and these observations have implications for the thermal history of the intrusion.Mg-skarns and breccias are developed in the roof of the main body of the intrusion.Within the intrusion,the taxitic rocks contain vesicles and the blebby sulfides developed in the picritic and taxitic gabbrodolerites appear to have a linkage to volatile phases.Cuprous sulfide mineralization developed at the roof of the Kharaelakh Intrusion is associated with metamorphosed and skarn-bearing country rocks,and appears to have been generated by a combination of sulfide fractionation and associated metasomatism.The geological relationships appear consistent with a chonolith model for the development of the differentiated intrusion and mineralization,but the extent of metasmorphism of the country rocks appears to be related to the unusual thickness of gabbrodolerite apophyses at the flanks of the intrusion rather than metamorphism produced by the passage of mafic magma through the intrusion.Variations in disseminated sulfide compositions and metasomatic textures in the skarns are described,and a model is proposed which balances traditional views on the evolution of the magma conduits with the impact of magmatic fluids transported through the magma column(i.e.transmagmatic fluids).The importance of structures in controlling the nature of the conduit,and the resultant small intrusions with excess sulfide is a feature of many other Ni-Cu sulfide deposits including Voisey′s Bay,and it is suggested that the sulfides are more likely to have beentransported from depth into their final resting place rather than developed by in-situ equilibration of sulfide with fresh magma in the chonolith.  相似文献   

18.
Chromium pollution were investigated by sampling the abandoned chromium contaminated sites in Chongqing. Its health risk was assessed following the procedures made by USEPA. The results showed that the most seriously polluted land was found at the former production area （G4） with average Cr（VI） concentration of 3369.2 mg kg-1 on the surface soil. The assessment indicated that there was high risk of non-carcinogens for children. The assessed risk of the first layer of office area （G1） for children, chromium slag transition （G2）, drainage pipeline chromium slag transition （G3） and production area （G4） for both children and adults were not acceptable （〉1.00× 106）. It was strongly suggested that the accessible measures of remediation should be taken for a portion of contaminated sites before the reuse of abandoned lands.  相似文献   

19.
Fresh rocks sampled from the 14.0°S hydrothermal field of the South Atlantic Ridge can be divided into two categories： olivine-gabbro and basalt. The olivine-gabbro is composed mainly of three types of minerals： olivine, clinopyroxene and plagioclase, while a multitude of melt inclusions occur in the plagioclase phenocrysts of the basalts. We analyzed the whole-rock, major and trace elements contents of the basaks, the mineral chemistry of phenocrysts and melt inclusions in the basalts, and the mineral chemistry of olivine-clinopyroxene-plagioclase in the olivine-gabbro, then simulated magma evolution within the crust using the COMAGMAT program. The whole-rock geochemistry shows that all the basalts exhibit typical N-MORB characteristics. In addition, the mineral chemistry characteristics of the olivine-gabbro （low-Fo olivine, low-Mg# clinopyroxene, high-TiO2 clinopyroxene, low-An plagioclase）, show that strong magma differentiation occurred within the crust. Nevertheless, significant discrepancies between those minerals and phenocrysts in the basalts （high-Fo olivine, high-An plagioclase） reflect the heterogeneity of magma differentiation. High Mg# （-~0.72） melt inclusions isobaric partial crystallization simulations suggest that the magma differentiation occurred at the depth shallower than 13.03 km below the seafloor, and both the vertical differentiation column shows distinct discrepancies from that of a steady-state magma chamber. Instead, a series of independent magma intrusions probably occurred within the crust, and their corresponding crystallized bodies, as the primary high-temperature thermal anomalies within the off-axis crust, probably act as the heat source for the development of the 14.0°S hydrothermal system.  相似文献   

20.
The Shewushan gold deposit is located 16 km southwest of Jiayu County, Hubei Province, eastern China, which is the largest lateritic gold deposit in Asia, consisting of a series of mineralized faults containing gold grades of 1.0–19.5 g/t set within a larger, lower-grade(0.2–1.0 g/t) zone. According to the fluid inclusions study, the homogenization temperature ranges from 70–350℃, and concentrates between 140–220℃. The laser Rama results show that the CO2 and CH4 exist in mineralized fluid. In addition, the major and trace element and REE geochemical data show that the genesis of the siliceous rocks is hydrothermal genesis, formed by mineralized fluid bearing SiO2 transmitted along faults to the surface, and replace the carbonate rocks to begin deposition. Primary gold mineralization is attributed to hydrothermal activity that followed the main period of tectonic deformation of the Indosinian orogeny, which caused the regional detachment regime in southeast Hubei. The reversed fold and the fault system formed the fluid migration channel in the Shewushan area. EPMA results show that Au exists in arsenopyrite(850×10-6–1550×10-6 Au) and pyrite(470×10-6–1340×10-6 Au). Therefore, based on the above results and combined with the field observation, we suggest that the genesis of primary orebody in Shewushan deposit is carlin type, while not weathered residual type.  相似文献   

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