大兴安岭中段晚更新世炭质层的发现及地质意义     

李世超  李廷栋  刘正宏  徐仲元  耿树方  王兴安  彭媛媛 《吉林大学学报(地球科学版)》2012,(Z1):314-318

大兴安岭中段莫克河地区发现一层位于玄武岩下部烘烤成因的炭质层,经加速器质谱测年技术(AMS)14C测定,该炭质层的年龄为(41 925±340)a BP,表明其形成时代为晚更新世。由此可以确定此期火山喷发为晚更新世,而非前人认为的渐新世;依据炭质层所在地质剖面,反演莫克河地区晚更新世后的火山活动过程,将大兴安岭地区新生代火山活动分为新近纪中期和第四纪晚期2期。该炭质层年龄的确定为大兴安岭中段晚更新世以来气候、环境变迁、大兴安岭隆升史等科学研究提供了直接证据。  相似文献   

陕西省凤县温江寺金矿地质地球化学特征及找矿          下载免费PDF全文

代军治袁旭东  陈少迅李永勤  原连肖王 涛 郭 路 刘莉霞 蒋 蕊 《中国地质》2011,38(3):692-700

温江寺金矿是西秦岭东部地区三叠纪地层中新发现的一个金矿。容矿地层主要是钙质板岩和含炭钙质板岩。矿(化)体呈透镜状、扁豆状分布于钙质板岩和炭质板岩中。区内成矿元素为Au、As、Sb、Hg、Pb、Zn等低温蚀变组合,地质特征显示出微细浸染型金矿特征。各类岩(矿)石的地球化学分析表明,从矿石到泥质板岩再到花岗岩脉,Al2O3和K2O+Na2O含量逐渐升高,而CaO含量、K2O/Na2O具降低趋势;矿石中As、Bi、Co、Ni、Cu、W、V、Tu、U等微量元素含量和ΣREE、LREE/HREE、稀土配分模式与容矿地层相近,而与花岗岩脉不同。地球化学特征显示,温江寺金矿成矿物质主要来源于容矿地层,与岩浆活动关系不密切。该金矿的发现,使得西秦岭三叠系沉积建造中金矿找矿有进一步向东延伸的可能。  相似文献   

Chemical composition of PM2.5 at an urban site of Chengdu in southwestern China     

陶俊  成天涛  张仁健  曹军骥  朱李华  王启元  罗磊  张雷鸣 《大气科学进展》2013,30(4):1070-1084

PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annual average of PM2.5 was 165g m－3, which is generally higher than measurements in other Chinese cities, suggesting serious particulate pollution issues in the city. Water soluble ions contributed 43.5% to the annual total PM2.5 mass, carbonaceous aerosols including elemental carbon and organic carbon contributed 32.0%, and trace elements contributed 13.8%. Distinct daily and seasonal variations were observed in the mass concentrations of PM2.5 and its components, reflecting the seasonal variations of different anthropogenic and natural sources. Weakly acidic to neutral particles were found for PM2.5. Major sources of PM2.5 identified from source apportionment analysis included coal combustion, traffic exhaust, biomass burning, soil dust, and construction dust emissions. The low nitrate: sulfate ratio suggested that stationary emissions were more important than vehicle emissions. The reconstructed masses of ammonium sulfate, ammonium nitrate, particulate carbonaceous matter, and fine soil accounted for 79% of the total measured PM2.5 mass; they also accounted for 92% of the total measured particle scattering.  相似文献   

滩间山花岗质岩石化学特征和脉岩型金矿成矿作用的关系     

白开寅  陈丽秋  魏刚锋 《地球科学与环境学报》2007,29(3):252-255,279

通过对青海滩间山金矿花岗质岩石的岩石化学、稀土元素和铅同位素研究,证明了和金矿有关的花岗质岩浆源于加里东期基性超基性岩的部分熔融或同源玄武岩分离结晶。岩浆中富金属硫化物的热液以及岩浆自身的热能,为地层和岩浆中金元素的活化和运移提供了能量和载体,对金起着捕获和富集的作用,有利于金矿床的形成。  相似文献   

Establishing the sediment stratigraphy of reservoirs in the southern Pennines,UK     

L. SHOTBOLT  S. M. HUTCHINSON  A. D. THOMAS 《水文科学杂志》2013,58(5):701-714

Abstract

Reservoirs in the southern Pennines have been investigated to determine their potential for reconstructing a history of atmospheric pollution. A selection procedure has been used to identify sites with the best chance of obtaining a usable sedimentary record prior to sample collection. Five reservoirs were selected for core collection and sediment analysis using magnetic susceptibility (χlf), particle size, spheroidal carbonaceous particle (SCP) analysis and radiometric dating. Analysis reveals that largely undisturbed sedimentary records exist in the deepest zones of these reservoirs, thus reservoir sediments represent a valuable resource for investigating pollution histories in the southern Pennines.  相似文献   

Pollution and eutrophication history AD 1800–2005 as recorded in sediments from five lakes in Central Chile     

Lucien von Gunten  Martin Grosjean  Urs Eggenberger  Philipp Grob  Roberto Urrutia  Arturo Morales 《Global and Planetary Change》2009,68(3):198-208

One of the fundamental problems to quantifying past impact of anthropogenic activities is that long series of observational data for pollutant deposition and changes in the nutrient cycling of ecosystems (eutrophication) are often not available. Lake sediments may provide suitable archives to decipher the history of local and regional pollution and eutrophication.Here we provide quantitative high-resolution data for the history of airborne pollutants and eutrophication from sediments of five lakes in Central Chile between ca. AD 1800–2005. We use spheroidal carbonaceous particles (SCPs) from fossil fuel combustion and excess atmospheric Cu deposition from mining activities as a proxy for atmospheric deposition. Organic carbon and nitrogen flux rates to the sediments and C/N ratios are used as a proxy for aquatic primary production and eutrophication.We show that the lake sediment SCP and Cu records are highly consistent and depict in great detail the local and regional history of urban, industrial and transportation history as reported in independent documentary sources and statistics. The pre-industrial and pre-1950 background concentrations (and flux rates) of the substances can be quantified. We can also show that technical measures taken in the early 1980s to trim down Cu emissions from the copper mines reduced the excess atmospheric Cu fallout to the lakes by about 50%.Eutrophication of the lakes did not start before ca. 1980. Prior to that time, warm season temperatures explain most of the variance in TOC and N flux to the sediments. The three dimictic lakes show only moderate eutrophication responses to enhanced N supply (as atmospheric fallout; enrichment factors for TOC and N 1.1–2.6), suggesting that mainly phosphorus controls aquatic primary production. The meromictic lake, where phosphorus recycling is likely, shows the largest response (enrichment factors for TOC and N between 9–20).While all five lakes show overall consistent and similar trends for the pollution history during the 19th and 20th century, there are significant differences in the details of the individual profiles. This suggests that local sources are highly important and the common regional (background) signal is relatively marginal. This is very different from Europe.  相似文献   

炭质泥岩Re-Os和碎屑锆石U-Pb同位素定年对广东大宝山铜矿床成矿时代的约束   总被引：1，自引：0，他引：1  

刘武生  赵鸿  赵如意  秦锦华  张熊  蒋金昌  赵晨辉  李挺杰  王成辉 《岩矿测试》2022,(2):300-313

Re-Os同位素作为一种强有力的技术工具,在黑色页岩沉积时代的精确定年中得到了广泛应用.随着高精度负离子热电离质谱(N-TIMS)测试技术的发展,炭质泥岩Re-Os同位素年龄测试越来越多地被应用于厘定沉积时代.广东省大宝山铜矿成岩成矿时代争议一直是制约成因机制研究的关键因素.本文通过Carius管中逆王水溶解炭质泥岩粉...  相似文献   

Palaeolimnological evidence for recent climatic change in lakes from the northern Urals, arctic Russia     

Nadia Solovieva  Vivienne J. Jones  Larisa Nazarova  Stephen J. Brooks  H. J. B. Birks  John-Arvid Grytnes  Peter G. Appleby  Tommi Kauppila  Boris Kondratenok  Ingemar Renberg  Vasily Ponomarev 《Journal of Paleolimnology》2005,33(4):463-482

The recent sediments from two deep arctic lakes, Mitrofanovskoe and Vanuk-ty, situated in the permafrost belt within the Bolshezemelskaya Tundra in the northern Ural region, were studied for diatoms, chironomids, spheroidal carbonaceous particles and stable lead isotopes. The magnitudes and rates-of-change in diatom and chironomid assemblages were numerically estimated. Instrumental climate records were used to assess statistically the amount of variance in diatom and chironomid data explained by temperature. August and September air temperatures have a statistically significant effect on diatom composition at both lakes. At Mitrofanovskoe Lake, major compositional changes in diatom and chironomid assemblages occurred at the turn of the 20th century and might be related to the regional increase in temperature. Chironomid-inferred air temperature also increased by approximately 1 °C since the early 1900s. At both lakes diatom compositional changes, coincident with the increase in June and September temperatures, also occurred in the late 1960s. These compositional changes are correlated with the increase in diatom production, sediment organic content and diatom species richness, and are likely to be a diatom response to the lengthening of the growing season. These changes are also correlated with the circum-Arctic temperature increase from the 1960s. A chironomid response to the late 1960s temperature increase was less pronounced at both lakes. Pollution levels are relatively low and pollution history is unrelated to ecological changes. Both lead isotopes and spheroidal carbonaceous particles show a clear atmospheric pollution signal, peaking in the 1980s.  相似文献   

A method for the extraction of carbonaceous particles from lake sediment   总被引：10，自引：0，他引：10  

N. L. Rose 《Journal of Paleolimnology》1990,3(1):45-53

The methods found in the literature for the extraction of carbonaceous particles from lake sediment are discussed. The technique used by Griffin & Goldberg (1975) on Lake Michigan sediments was improved by modifying the procedure to halve the extraction time and reduce the risk of fragmentation. This method was then applied to a sediment core taken from Loch Tinker in Western Scotland, which had previously been analysed using the Renberg & Wik method. Although the basic trends for both methods are the same, the new method is found to be more sensitive to low particle numbers and more accurate, due to a more efficient extraction and a higher magnification for microscope counting.  相似文献   

广西平乐硅灰石矿工艺矿物学研究     

蒋述兴 《矿物学报》2001,21(3):485-488

对广西平乐硅灰石矿的化学成分和矿物组成进行了分析确定，对硅灰石及其伴生矿物的结构构造特征进行了查定，主要对硅灰石中碳质物的赋存特征进行了研究，发现硅灰石矿石中的碳质物分别与硅灰石、方解石、石英等多种矿物以多种形式紧密伴生，认为要提高平乐硅灰石粉的白度，除了要尽可能除去透辉石、石榴石等矿物杂质及含铁、锰等的氧化物杂质外，关键还要使碳质物单体解离，并除去碳质物杂质。  相似文献