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841.
Yves?CouillardEmail author Antonella?Cattaneo Céline?Gallon Michel?Courcelles 《Journal of Paleolimnology》2008,40(1):97-114
Sources and chronologies of metal contamination were studied in sediment cores of three lakes of the Rouyn-Noranda mining
area (Québec, Canada) affected by atmospheric deposition of anthropogenic contaminants. One of the three lakes also received
acid mine drainage. The sediments were dated using 210Pb and 137Cs and analysed for stable Pb isotope ratios and for total concentrations of 15 elements (Ag, Al, Au, Ca, Cu, Cd, Fe, Hg,
Mn, Ni, P, Pb, S, Ti, Zn). Stable lead isotopic signatures helped to determine the quantitative contributions of different
industrial Pb sources to our sampling sites. This source apportionment showed the dominant influence of the Rouyn-Noranda
copper smelter in airborne Pb emissions for the decades following 1926, when industrialization began in the region. The smelter
source had a low ratio of 206Pb/207Pb ranging between 0.90 and 1.05, as typical of the Abitibi Archean sulphides. The relationships between element (metal) sedimentary
fluxes and anthropogenic Pb fluxes allowed us to infer the origin of the anthropogenic source. These relationships strongly
suggest that the copper smelter was (and may still be) an atmospheric source of Cd, Cu, Pb, Zn, Ag and Hg to the surrounding
lakes. Our study indicates that the efforts made by the Rouyn-Noranda copper smelter to reduce airborne emissions of metals
have been translated in reduced atmospheric metal loadings to the surrounding lakes. 相似文献
842.
通过对过马营-同仁一带侵位于晚三叠世陆相火山岩中的印支期花岗岩类杂岩体的岩石学、岩石化学、地球化学、稀土元素定量模拟、Sr 同位素资料的初步研究,结合大地构造背景分析认为该杂岩体属壳型或S 型花岗岩类,由于岩浆成分受陆壳源岩成分的控制,又具有过渡型或同熔型花岗岩的某些特点。 相似文献
843.
震源体破裂行为的重整化群方法研究 总被引:2,自引:0,他引:2
应用重整化群方法对一维、二维和三维震源体的破裂问题进行了研究,得到了一维、二维和三辰原体破裂的临界概率值分别国0.2063、0.1707和0.1599,相关长度指数分别为1.4388、0.8084和0.5757。进而由此揭示了临界概率和相关长度指数随维数增大而减少的变化规律。 相似文献
844.
The southern Bida Basin in central Nigeria forms a part of the larger Bida or Middle Niger Basin, which is contiguous with the south east trending (petroliferous) Anambra Basin. These basins were major depocenters for Campanian–Maastrichtian sediments in southern and central Nigeria prior to the build up of the Tertiary Niger delta. The successions in the southern Bida Basin consist of the basal Lokoja Formation, overlain by the Patti Formation and capped by the Agbaja Formation. The Lokoja Formation is a sequence of matrix supported conglomerates and sandstones overlying the Pre-Cambrian to Lower Paleozoic basement. Depositional environments are predominantly within fluvial systems of a continental setting. The Patti Formation consists of dark grey carbonaceous shales; mudstone and siltstones representing flood plains to shallow marine deposits with likely organic rich intervals. The overlying Agbaja Formation is made up of ferruginised oolitic and kaolinitic mudstone of a marginal marine environment. Twenty samples of shales of the Patti Formation were studied by incident light microscopy and geochemical analysis to determine the maceral components, geochemical type and potential yield of the pyrolysate. Maceral analysis indicate a large abundance of vitrinite (50–85%; mean = 66%); moderate abundance of liptinites (10–33%; mean = 18%) and lesser amounts of inertinite (9–40%; mean = 16%). Total organic carbon (TOC) values vary from 0.17 to 3.8 wt.% (mean = 2.1 wt.%) with most samples having greater than 2 wt.% TOC. Three of the samples yield greater than 2 kg(HC)/ton of rock suggesting a fair source rock potential. Most of the samples are thermally immature to marginally mature with vitrinite reflectance ranging from 0.4 to 0.6% Rom and Tmax values of 407–426 °C. Given the prevalence of the humic Type III kerogen, maturity and hydrocarbon potential yields, we conclude that the Patti Formation source rock facies have moderate to fair potential for gaseous hydrocarbons which have not yet been generated at the present day outcrop levels but could be important gas source where buried down-dip. 相似文献
845.
断层面上某一点的滑动时间函数需要用三个参数来表达:断层的平均位错量、上升时间和破裂传播的时间延迟。本文基于有限断层模型,根据断层面上每个子源的位错量时、空不均匀分布特征,采用Brune模型系统确定了相应滑动时间函数的三个参数,构建了位错量呈时、空不均匀分布的有限断层滑动模型。该方法可以表现破裂面上断层位错量在时间和空间上分布的不均匀特征,既能够表现震源的复杂性同时又能够简化震源模型的构建过程,为考虑断层附近的强地震动数值模拟计算提供了有效的途径。 相似文献
846.
847.
长江源各拉丹冬地区上三叠统结扎群双壳类组合与古环境 总被引:1,自引:0,他引:1
在长江源各拉丹冬地区雀莫错一带上三叠统结扎群采获大量双壳类化石,根据产出层位,建立了Quemocuomegalodon orientus-Neomegalodon boeckhi、Halobia superbescens-Halobia disperseinsecta、Amonotis togtonheensis-Cardium(Tulongocardium)xizangensis3个组合.这一生物组合反映的地质时代为诺利期,依据双壳类化石的外部形态和内部构造特征及围岩岩石化学分析,说明垂向上双壳类生活的结扎群具浅—深—浅的古地理变化特征,为区域上地层对比及生物生存环境提供了基础资料. 相似文献
848.
滇东岩溶区表层岩溶水源地特征及其开发利用 总被引:1,自引:0,他引:1
表层岩溶水源地是解决分散农村生活用水困难的重要水源,而且分布广泛,水质较好。但水源地含水介质的富水性不均匀,岩溶水动态变幅大,脆弱性突出,易受污染和生态环境变化的影响。由此,表层岩溶水源地生态环境建设及保护尤为重要。表层泉以池、管调蓄系统开发最为有效。表层富水块段适宜打浅井开发,建设庭院式供水工程。采用地质雷达验证地质认识,确定井位,是经济有效的技术手段。 相似文献
849.
达金海相碎屑岩出露于西藏冈仁波齐峰山脚下,长期以来,该套岩石与冈底斯砾岩一起被视为印度-亚洲板块碰撞形成的陆相磨拉石.该套岩石组合是由凝灰质粉砂岩、杂砂岩、含砾杂砂岩和砾岩组成的一套深海-浅海相沉积组合.杂砂岩、砾岩碎屑组成与地球化学组成研究表明,该套岩石组合的形成与岛弧的发展密切相关,源区大地构造背景以岛弧为主,但也存在被动大陆边缘和碰撞构造带(蛇绿混杂带)两个不同构造背景的源区.区域上,在该套岩石组合的北侧存在着冈底斯岛弧带,南侧为雅鲁藏布蛇绿混杂带.这些特征共同表明,达金海相碎屑岩是西藏雅鲁藏布缝合带与冈底斯岛弧带之间的日喀则弧前盆地的一部分. 相似文献
850.
European geodetic very long baseline interferometry (VLBI) sessions (also known as EUROPE sessions) have been carried out
on a regular basis for the past 15 years to study relative crustal motions within Europe. These sessions are based on observations
of extragalactic radio sources, which serve as distant fiducial marks to establish an accurate and stable celestial reference
frame for long-term geodetic measurements. The radio sources, however, are not always point-like on milliarcsecond scales,
as VLBI imaging has revealed. In this work, we quantify the magnitude of the expected effect of intrinsic source structure
on geodetic bandwidth synthesis delay VLBI measurements for a subset of 14 sources regularly observed during the EUROPE sessions.
These sources have been imaged at both X-band (8.4 GHz) and S-band (2.3 GHz) based on dedicated observations acquired with
the European VLBI Network (EVN) in November 1996. The results of this calculation indicate that the reference source 0457+024
causes significant structural effects in measurements obtained on European VLBI baselines (about 10 picoseconds on average),
whereas most of the other sources produce effects that are only occasionally larger than a few picoseconds. Applying the derived
source structure models to the data of the EUROPE5-96 session carried out at the same epoch as the EVN experiment shows no
noticeable changes in the estimated VLBI station locations. 相似文献