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1.
Discussed in this paper are the regularities governing the prevalence of Keshan disease and its relationship te the local rock type, soil, vegetation, climate and landform, as well aa to the characteristic variations of stereo-environment- environmental gradient in Yunnan Province. Based upon the foregoing discussion, the gradations of environmental quality and the coefficients of environmental quality mirroring the general picture of physical environment there have been determined, and a model of environmental quality has been established with an attempt to detail the relationship between the factors of environmental geology and Keshan disease.  相似文献   

2.
Dating of metallic ore deposits has been one of the problems concerned with by ore geologists for many years.The establishment of the Re-Os Isotope Laboratory at the Institute of Rock and Mineral Analysis,Chinese Academy of Geological Sciences, has provided us with a new technique to carry out geochronological studies of molybdenum ores.As one of the most important Re-bearing minerals, molybdenite contains almost no common osmium, but ^187Os was derived completely from decay of ^187Re, with ^187Os content as the function of Re content in the mineral .An ID-ICP-MS technique has been used in this study,and Re-Os isotopic ages of several large molybdenum deposits of differ-ent types from the East Qinling molybdenum belt have been determined.It is indicated that the Huanglongpu carbonatite vein-type molybdenum-(lead) deposit has a Re-Os age corresponding to Indosinian,while the rest porphyry-type molybdenum deposits and porphyry-skarn-type molybdenum-(tungsten) deposits have Re-Os ages corresponding to Yenshanian.  相似文献   

3.
邓华兴 《地球化学》1980,(4):368-374
Experimental data on cathodeluminescence of 34 individual specimens of naturallyoccurring apatite differring in the mode of occurrence are presented in this paper.In accordance with the characteristic distribution of the bands and lines of apatite specimens,it has been confirmed that RE ions Sm^2 ,Dy^3 ,En^2 ,etc.,are the main activators for the cathodeumineseence of apatite.In conjunction with the crystallological study.a priliminary investigation into the mechanism for apatite cathodelnminescence has been made as well.The author has suggested that the cathodelumineseence of apatite may be attributed to the replacement of Mn at the site of Can by Mn^2 ,and the luminous colour seems to have no direct,simple correlation with that of the crystal itsself.  相似文献   

4.
Foreword     
Since the discovery of a lot of eclogites with coesite and diamond inclusions related to the continent-continent collision-orogeny environment,the ultrahigh-pressure metamorphism (UHPM) in the Dabie-Sulu has aroused great interest in geologists. Experimental studies have proved that such  相似文献   

5.
The Ordos Basin of North China is not only an important uranium mineralization province, but also a major producer of oil,gas and coal in China.The genetic relationship between uranium mineralization and hydrocarbons has been recognized by a number of previous studies,but it has not been well understood in terms of the hydrodynamics of basin fluid flow.We have demonstrated in a previous study that the preferential localization of Cretaceous uranium mineralization in the upper part of the Ordos Jurassic section may have been related to the interface between an upward flowing,reducing fluid and a downward flowing,oxidizing fluid.This interface may have been controlled by the interplay between fluid overpressure related to disequilibrium sediment compaction and which drove the upward flow,and topographic relief,which drove the downward flow.In this study,we carried out numerical modeling for the contribution of oil and gas generation to the development of fluid overpressure,in addition to sediment compaction and heating.Our results indicate that when hydrocarbon generation is taken into account,fluid overpressure during the Cretaceous was more than doubled in comparison with the simulation when hydrocarbon generation was not considered.Furthermore,fluid overpressure dissipation at the end of sedimentation slowed down relative to the no-hydrocarbon generation case.These results suggest that hydrocarbon generation may have played an important role in uranium mineralization,not only in providing reducing agents required for the mineralization,but also in contributing to the driving force to maintain the upward flow.  相似文献   

6.
On l lth September 2013, the Inner Mongolia Mineral Resources and Reserves Evaluation Center estimated that the world's third-largest molybdenum deposit had been found in the Caosiyao area of Xinghe County, Inner Mongolia, NE China. The find has 130235.60×10^4 t of (122b)+(333) molybdenum ores, a metal amount of 1327649.27 t, with Mo grade of 0.102-a super-large one.  相似文献   

7.
Proceeding from gaining a knowledge of the structural settings in this area, the authors applied remotesensing techniques and selected multi-temporal image processing to extract information of buried structures inthe Beijing plain area. Good results have been achieved. Through an integrated analysis of remote-sensing, geo-logical, seismic and aeromagnetic data, it is pointed out that there exist two sets of buried fractures of differingtrends and orders-the northeast set and the northwest set. forming a rhombic framework in the images. Thetwo sets of fractures have still been active since the Quaternary. which is of practical signifcance for geologicalstudy, earthquake prevention and planning of urban construction in the area. The results demonstrate that theselection of multi-temporal processing of remote sensing images and the integrated analytic method are impor-tant in the study of buried structures.  相似文献   

8.
The mining environment, medical geology and urban geochemistry form a group of related scientific disciplines that have developed strongly during recent years in the Nordic countries. Modern legislation controls the environmental issues. Close co-operation of researchers and legislators has improved the quality and safety of life in the societies of the Nordic countries. In mining environmental studies, methods that are suitable in Arctic conditions have been developed; in medical geology, the input from the Nordic countries has made it an appreciated scientific discipline throughout the world, and in the case of the urban environment, methods developed by our geochemists have especially improved the health conditions, particularly of children.  相似文献   

9.
我国地方性氟病的地球化学问题   总被引:18,自引:0,他引:18  
Endemic fluorine disease is a chronic fluorine poisoning caused by high level of fluorine in drinking water or foods. Incidence of this disease has been knowu in many parts of the world. In China its occurrence has been observed in the Northeast, Northwest, Southwest and some other localities. Investigation shows that it is closely related to geochemical environment: Major fluorine sources in nature include fluorinerich volcanic rocks, calcareous dolomites, phosphorus-bearing rocks/loess and Quarternary loose sediments. Under special conditions fluorine is concentrated in ground water or soil and seeks its way into human body through diet. Areas With high fluorine concentration responsible for the fluorine disease can be classified into four types, depending on characteristics of geochemical environment: (1) Arid and semiarid calcium-rich soda saline areas; (2) Semiarid, alternatively marine-terrestrial strata with a high degree of salinity; (3) Semihumid iron- and aluminum-rich intermediate-acid soils; (4) Localities where fluorine-rich rocks or deposits are developed;and those with high fluorine content as a result of industrial pollution. Based on medical statistics and chemical analyses, of water, soil, food and other related samplcs,this work will provide a scientific baekground for the prevention and control of fluorine disease.  相似文献   

10.
When first asked to write a paper for inclusion in the Grabau Anniversary Volume of the Bulletin it was but natural that the fascinating topic of palaeogeography should suggest itself as one appropriate to the occasion, since it has been in this field that Dr. Grabau's classic contributions have most directly influenced the development of Cenozoic research in China.  相似文献   

11.
The Salmas geothermal field is located in NW Iran. Subduction of Neo-Tethys oceanic crust beneath the Iranian microcontinent caused to propagation of the magmatic-Arc. Fractures and faults in the convergent zone have created path-ways for the circulation of geothermal fluid. Fracture concentration in the Salmas geothermal field has been characterized using of the fractal method and creation of a fracture density map that shows the highest concentration in the central part of the study area. The permeability of fractures has been evaluated by analyzing their orientation in respect to the paleostress axes. Also, the fractal analyzing result indicates the maximum fractal dimension (1.96) is around the thermal spring outlet. Paleostress analyzing revealed that in the central part of the study area, σ1 axes orientation is S90°W/10° and the σ2 dip is near to the vertical in this stress field, where strike slip faults can be propagated. In the SE part near the recharge of the thermal springs, the σ3 plunge increases to 70? and σ1 orientation is N15°E/20°, in this local tectonic regime thrust fault developed. Fractures have an important role in the circulation of fluid and the fractal dimension increases near the thermal springs in the Salmas geothermal field. Regarding the paleostress data fracture with N-S direction such as the F1 fault zone (parallel to the σ1 axes), a suitable pathway for deep circulation of geothermal fluid flow has been created.  相似文献   

12.
Fossil ferns are abundant and diverse in the Permian Cathaysian Flora of Shanxi, North China. Although plants assemblages of the Carboniferous and Permian have been extensively investigated, their palaeoecology and especially the paleoecology of ferns has not been studied in detail. Recent reinvestigation of Oligocarpia gothanii has revealed its growth habit and cloning reproduction strategy, but most previous studies lack integrated sedimentological and taphonomic data. In this study, new materials of O. gothanii have been collected from a floodplain setting in the middle Permian Lower Shihhotse Formation of southeastern Shanxi. These plant fossils were found in a lenticular claystone associated with rooting structures. They are characterized by aphlebia at the base of the penultimate rachis. Sedimentological, taphonomic and morphological analyses were conducted to understand the growth habit and ecology of the fern. The result indicates that the Oligocarpia gothanii had a prostrate, ground cover growth habit, and was dominant in pioneer floras that colonized disturbed floodplains.  相似文献   

13.
It is generally acknowledged that geomagnetic polarity has reversed many times in geological history and an abnormal geologic phenomenon is the Cretaceous normal superchron. However, the causes have been unknown up to now. The nonlinear theory has been applied to analyze the phenomenon in geomagnetic polarity reversal and the Cretaceous normal superchron. The Cretaceous normal superchron implies that interaction of the Earth’s core-mantle and liquid movement in the outer core may be the lowest energy state and the system of Earth magnetic field maintains a sort of temporal or spatial order structure by exchanging substance and energy in the outside continuously. During 121-83 Ma, there was no impact of a celestial body that would result in a geomagnetic polarity reversal, which may be a cause for occurrence of the Cretaceous normal superchron.The randomness of geomagnetic polarity reversal has the self-reversion characteristic of chaos and the chaos theory gives a simple and clear explanation for the dynamic cause of the geomagnetic polarity reversal.  相似文献   

14.
Fossil ferns are abundant and diverse in the Permian Cathaysian Flora of Shanxi, North China. Although plants assemblages of the Carboniferous and Permian have been extensively investigated, their palaeoecology and especially the paleoecology of ferns has not been studied in detail. Recent reinvestigation of Oligocarpia gothanii has revealed its growth habit and cloning reproduction strategy, but most previous studies lack integrated sedimentological and taphonomic data. In this study, new materials of O. gothanii have been collected from a floodplain setting in the middle Permian Lower Shihhotse Formation of southeastern Shanxi. These plant fossils were found in a lenticular claystone associated with rooting structures. They are characterized by aphlebia at the base of the penultimate rachis. Sedimentological, taphonomic and morphological analyses were conducted to understand the growth habit and ecology of the fern. The result indicates that the Oligocarpia gothanii had a prostrate, ground cover growth habit, and was dominant in pioneer floras that colonized disturbed floodplains.  相似文献   

15.
<正>1 Introduction The Qin-Hang suture zone is the most important polymetallic metallogenic zone in southern China[1-2]and has the greatest resource potential.In recent years,a group of molybdenum(Mo)deposits have been discovered in the northeastern part of the Qin-Hang belt[3].From Mar.2006to Dec.2014,the Jiangxi Copper Group Geological Exploration Engineering Co.,Ltd.conducted prospecting,  相似文献   

16.
Nan suture in northern Thailand, representing a complex zone with complex geology and structures, has been selected for airborne geophysical investiga-tions. The suture has been widely accepted as an early Triassic collision zone between Shan-Thai and Indo-china microcontinental blocks. Our field data suggest the occurrence of a mélange zone in response to com-pression tectonics. Moreover, previous petrochemical and field investigations suggest that the Nan suture may have been formed as a result of a subduction zone.  相似文献   

17.
The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD=1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153±3 Ma and model ages of 150.2±2.1 Ma – 155.4±2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Huangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150–170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2–6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1–4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133~135 Ma, 150–162 Ma, and 166–170 Ma, respectively. The 150–162 Ma-stage is in accordance with ages of large-scale W-Sn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.  相似文献   

18.
The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining. The environmental impact of long-term mining activities cannot be ignored. It is of great significance to study the ecological risk and the accumulation trends of heavy metals in the soil of mining areas for scientific prevention and control of heavy metal pollution. Taking the Taowanbeigou River Basin in the mine concentration area as the research object, the ecological p...  相似文献   

19.
Presented in this paper are the rypes,salinities,homogenization temperatures and organic components of fluid inclusions formed at the four stages of diagenetic authigenesis in the Eogene of the Biyang Depression.The results of cooling experiments on fluid inclusions were used to determine the fluid system and composition of saline aqueous solution in each of the stages .The homogenization temperatures of saline aqueous solution inclusions and hydrocarbon organic inclu-sions have been corrected by two approaches ,and the trapping temperatures and pressures of fluid inclusions at each of the stages have been obtained.This strdy has shed light on the physicochemistry and evolution of diagenetic fluids.The diagentic fluid system is a system which was transformed from a chloride-bearing to a carbonate-bearing system along with the diagenic evolu-tion.The decrease of diagenetic temperature at Stage III of diagenetic authigenesis suggests that the depression would have experiences uplifting at that time.The fluorescent characteristics of fluid inclusions indicate the varieties of organic components in fluid inclusions both in time and in space.  相似文献   

20.
Benham Rise is a large igneous province that has been accreted to the eastern seaboard of northern Lu-zon since Early Miocene. It started forming during the Eocene at a hotspot/mantle plume in the vicinity of the Central basin Spreading Center in the West Philippine Basin (CBSC) of the Philippine Sea Plate. Seafloor spreading from the CBSC and Parece Vela pushed Benham Rise towards Luzon. Eventually Benham Rise jammed against Luzon at the end of the Oligocene, with consequences that impacted on the geology of the Philippines which have been similarly noted in colli-sions of large igneous provinces in other areas. These are manifested as follows:  相似文献   

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