现代海底的成矿作用与矿产资源     

张立生 《四川地质学报》1999,(4)

迄今所发现的现代海底成矿作用主要分布在沿大西洋中脊、东太平洋海岭和西太平洋沟弧盆系的各热液田中。现代海底成矿作用形成了大量具有重大经济意义的矿产,它们主要是铁锰结核、富钴结壳、多金属硫化物和被称之为２１世纪能源的气体水合物。现代海底成矿作用及其所形成矿床的研究是矿床前研究的前沿课题,它对于矿床学的发展,揭示成矿作用的奥秘和海底资源的开发都具有重大意义。  相似文献   

豫西杜关锰银矿田火山隐爆角砾岩特征及其形成机制     

魏俊浩  袁艳宾  刘晓峰 《地质论评》1999,45(7):631-635

豫西杜关锰银矿田火山隐爆角砾岩的形成主要与气液挥发分和超浅成的燕山期闪长岩及闪长玢岩有关,并受该地区近东西向深断裂的控制,而火山隐爆角砾筒又控制着杜关地区锰银矿床（点）的分布,豫西杜关锰银矿田由若干个矿床（点）构成,矿田内已发现多处隐爆角砾岩筒,这些火山机构均与成矿有密切的关系。本文介绍了两个主要火山隐爆角砾岩筒的地质特征,并论述了两类隐爆角砾岩的形成机制。原地棱角状火山角砾岩是由火山爆发震碎作用造成的,异地溶蚀状角砾岩是由流化作用造成的。  相似文献   

水温分层型水库铁、锰垂直分布特征   总被引：8，自引：2，他引：6  

徐毓荣  徐钟际  徐玮  向申  封珩 《湖泊科学》1999,11(2):117-122

贵阳市主要饮用水源地阿哈水库系水温分层型季节性缺氧水库,由于沉积物含高浓度Ｆｅ,Ｍｎ至使库水受到污染,经多年测定不同季节２０ｍ深垂直水柱结果表明,Ｆｅ,Ｍｎ分布随着季节变化,水库水温分层而变化,呈现明显的垂直分布规律,高浓度Ｆｅ,Ｍｎ主要出现在水温分层期水库中,下层,与库底缺氧,ＰＨ下降沉积物浓度Ｆｅ,Ｍｎ释放造成的二次污染等密切相关,从而为自来水厂实施优化分层取水和污染控制提供了依据。  相似文献   

BIOGEOCHEMICAL MECHANISM OF POSTDEPOSITIONAL MIGRATION OF Fe AND Mn IN LAKE AHA, CHINA     

万曦  万国江  黄荣贵  普勇 《中国地理科学(英文版)》1997,7(4):368-374

I.INTRODUCTIONLakeAhaisamedium--sizedartificialreservoirwithseasonallyanoxichypolirnnion,andawaterresourceofGuizhouProvince,China,builtin1958,workedin1960andexpandedin1982.Ithasadrainagebasinof190kmZwithaverageannualtemperatureof15.3tandprecipitationof1109rum.Openplantcover,containiflgshrubandgrass,surroundsthelake,andsialliticandstfeteyellowsoilisdevelopedonPe~ianlimestoneandcoallayer,meanwhile,OThisprojectwassupportedbytheNationalNaturalaudienceFOundationofChinaandtheaudienceFOund…  相似文献   

南极麦克斯韦尔湾及邻近海域高锰酸钾指数研究   总被引：1，自引：1，他引：0       下载免费PDF全文

袁峻峰  陈皓文  李永祺  吴宝铃 《极地研究》1998,10(3):55-59

为了研究南极水域的污染状况,于１９９３年１２月～１９９４年２月对南极麦克斯韦尔湾及邻近海域的高锰酸钾指数（ＣＯＤＭｎ）的变化和分布状况进行了监测。３９个站次的测值在０．３３４～１．９５９ｍｇ／Ｌ之间,符合中国《海水水质标准》（ＧＢ３０９７－８２）第一类水质（３．０００ｍｇ／Ｌ）要求。各考察站附近的测值高;长城湾内高于湾口及湾外。分析了湾内、湾口和湾外在１９９３年１２月、１９９４年１月及２月的变化情况和原因;对ＣＯＤＭｎ的主要来源进行了研究分析;并对南极长城站及邻近海域的环境保护和研究提出了建议。  相似文献   

水城徐家寨锰矿床地质特征及成矿模式     

朱和书 《四川地质学报》2014,(2):208-211

贵州水城徐家寨锰矿是该地区的一个重要锰矿典型矿床,通过对该矿床的基本地质特征及成矿进行研究、分析,初步总结出成矿模式。徐家寨锰矿最终定位于开阔台地沉积相的沉积-风化锰帽型矿床。  相似文献   

吉林西部锰、钼元素土壤地球化学特征     

施宪  王冬艳  李月芬  靳克  郭珍 《世界地质》2010,29(2):256-261

对农安、大安、通榆工作区表层土壤Mn、Mo元素全量和有效量、剖面土壤全量及葵花籽实中Mn、Mo元素含量的研究结果表明:吉林西部土壤表层Mn、Mo元素全量差异源于各区沉积物质的不同;吉林西部有效Mn含量丰富,有效Mo严重缺乏,Mn、Mo皆为强烈转化;表层土壤Mn、Mo元素有效量与全量、有机质含量呈极显著相关;各区葵花籽实中Mn、Mo两种元素含量差别较小,土壤pH值影响葵花对Mo元素的吸收。  相似文献   

Luminescent Properties and Decay Characteristics of CaS: Mn2 + Phosphor     

Cao Lin  Li Dianchao 《世界地质(英文版)》2000,3(2)

CaS:Mn2 + has been synthesized by a new sulfurizing flux method, and the phosphors prepared in this way is relatively stable in water. The fluorescent spectra of CaS host and CaS: Mn2 + have been measured at room temperature. The luminescent centers formed by O2 - ions may be responsible for the host' s blue - green emission. The complete disappearance ofthis emission in CaS: Mn2 + system confirms that there exists efficient energy transfer from the host to the Mn2 + centers.The decay characteristics have been performed. The photoluminescence decay of CaS: Mn2 + consists of slow and fast components due to the single and paired Mn2 + centers, respectively.  相似文献   

Potential of superelastic Cu–Al–Mn alloy bars for seismic applications     

Y. Araki  T. Endo  T. Omori  Y. Sutou  Y. Koetaka  R. Kainuma  K. Ishida 《地震工程与结构动力学》2011,40(1):107-115

We present the results of the quasi‐static cyclic tensile tests of Cu–Al–Mn shape memory alloy (SMA) bars of 4 and 8 mm diameters to examine their superelasticity and other mechanical properties closely related to seismic applications. The present Cu–Al–Mn SMA bars have achieved the recovery strains of over 8% and the fracture strains of over 17%. Low‐cycle fatigue was observed in neither of the bars. The mechanical properties obtained from the test, along with the lower material cost and higher machinability than Ni–Ti SMAs, demonstrate the high potential of the present Cu–Al–Mn SMA bars to be used in seismic applications. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Arsenic and other water‐quality issues affecting groundwater,Indus alluvial plain,Pakistan          下载免费PDF全文

Sadaf Naseem  John M. McArthur 《水文研究》2018,32(9):1235-1253

Groundwater beneath the alluvial plain of the Indus River, Pakistan, is reported to be widely polluted by arsenic (As) and to adversely affect human health. In 79 groundwaters reported here from the lower Indus River plain in southern Sindh Province, concentrations of As exceeded the WHO guideline value for drinking water of 10 μg/L in 38%, with 22% exceeding 50 μg/L, Pakistan's guideline value. The As pollution is caused by microbially‐mediated reductive dissolution of sedimentary iron oxyhydroxides in anoxic groundwaters; oxic groundwaters contain <10 μg/L of As. In the upper Indus River plain, in Punjab Province, localized As pollution of groundwater occurs by alkali desorption as a consequence of ion exchange in groundwater, possibly supplemented by the use for irrigation of groundwater that has suffered ion exchange in the aquifer and so has values >0 for residual sodium carbonate. In the field area in southern Sindh, concentrations of Mn in groundwater exceed 0.4 mg/L in 11% of groundwaters, with a maximum of 0.7 mg/L, as a result of reduction of sedimentary manganese oxides. Other trace elements pose little or no threat to human health. Salinities in groundwaters range from fresh to saline (electrical conductivity up to 6 mS/cm). High salinities result from local inputs of waste water from unsewered sanitation but mainly from evaporation/evapotranspiration of canal water and groundwater used for irrigation. The process does not concentrate As in the groundwater owing to sorption of As to soils. Ion exchange exerts a control on concentrations of Na, Ca, and B but not directly on As. High values of Cl/Br mass ratios (most ?288, the marine value) reflect the pervasive influence on groundwater of sewage‐contaminated water from irrigation canals through seepage loss and deep percolation of irrigation water, with additional, well‐specific, contributions from unsewered sanitation.  相似文献