陕西省洛南县莲花沟岩体LA-ICP MS锆石U-Pb年龄及地质意义     

张照伟  李文渊  赵东宏  高永宝  谢燮  张海松  彭素霞  李行 《地球学报》2008,29(6):811-816

在西起陕西省的金堆城地区,东至河南省栾川南泥湖-三道庄-上房沟、嵩县雷门沟地区的华北地台南缘的东秦岭钼矿带上产出的南泥湖、三道庄、上房沟等一系列钼矿床,均与燕山期中酸性小岩体成矿关系密切,并且成岩成矿年龄集中在110～160 Ma.同样位于该钼矿带上的洛南县莲花沟岩体,其侵位特点与岩石化学特征非常相似.笔者从陕西省洛南县莲花沟岩体地质背景人手,通过LA-ICP-Ms锆石U-Pb定年,获得莲花沟岩体年龄为(147.7±2.0)Ma.恰处于东秦岭钼主成岩成矿年龄范围,这对进一步指导该区的找矿工作,具有重要地质意义.  相似文献   

Environmental and legal aspects of karst areas   总被引：3，自引：0，他引：3  

P. E. LaMoreaux  W. J. Powell  H. E. LeGrand 《Environmental Geology》1997,29(1-2):23-36

 Environmental impacts on karst settings are common as they are more sensitive than those of other rock terrains. Regulatory procedures that are effective in other rock terrains are not necessarily applicable to karst settings. Development and exploitation by man that affect the karst hydrology regime can trigger catastrophic events and result in numerous legal actions where the effects of changes go beyond property boundaries. A great variety of regulations and examples of litigation exist for karst areas. Received: 25 October 1994 · Accepted: 17 October 1995  相似文献   

Element mobility during pyrite weathering: implications for acid and heavy metal pollution at mining-impacted sites   总被引：1，自引：0，他引：1  

Long Lu  Rucheng Wang  Fanrong Chen  Jiyue Xue  Peihua Zhang  Jianjun Lu 《Environmental Geology》2005,49(1):82-89

Based on back scattered electron images and electron micro-probe analysis results, four alteration layers, including a transition layer, a reticulated ferric oxide layer, a nubby ferric oxide layer and a cellular ferric oxide layer, were identified in the naturally weathering products of pyrite. These layers represent a progressive alteration sequence of pyrite under weathering conditions. The cellular ferric oxide layer correlates with the strongest weathering phase and results from the dissolution of nubby ferric oxide by acidic porewater. Leaching coefficient was introduced to better express the response of element mobility to the degree of pyrite weathering. Its variation shows that the mobility of S, Co and Bi is stronger than As, Cu and Zn. Sulfur in pyrite is oxidized to sulfuric acid and sulfate that are basically released into to porewater, and heavy metals Co and Bi are evidently released by acid dissolution. As, Cu and Zn are enriched in ferric oxide by adsorption and by co-precipitation, but they would re-release to the environment via desorption or dissolution when porewater pH becomes low enough. Consequently, Co, Bi, As, Cu and Zn may pose a substantial impact on water quality. Considering that metal mobility and its concentration in mine waste are two important factors influencing heavy metal pollution at mining-impacted sites, Bi and Co are more important pollutants in this case.  相似文献   

柴北缘达达肯乌拉山地区闪长岩锆石LA-ICP-MSU-Pb年龄、岩石地球化学特征及其构造意义   总被引：1，自引：0，他引：1  

刘永乐  刘智刚  张爱奎  何书跃  张大明  毛生元  李兴良  奎明娟 《矿床地质》2018,37(5):1079-1090

达达肯乌拉山位于柴达木盆地北缘中东部,区内发育闪长岩体,以小岩株形式产出。通过对达达肯乌拉山闪长岩岩石LA-ICP-MS锆石U-Pb定年和地球化学特征的研究,获得闪长岩体的年龄为(240.5±1.7) Ma,属早印支期。闪长岩体的w(K_2O)较高,为2.03%～2.30%,w(Na2O)含量较低,为3.2%～3.44%,为一套准铝质及弱过铝质高K、低Na的高钾钙碱性型I型花岗岩。岩石稀土元素总量为158.35×10~(-6)～200.41×10~(-6),球粒陨石标准化曲线向右倾斜,重稀土元素曲线呈水平状,轻稀土元素富集,但负铕异常不明显,岩浆分异程度不高。岩石的La/Ta(54.32～68.51)、Sm/Nd(0.18～0.19)及Rb/Sr(0.11～0.19)比值特征反映该岩体岩浆具有壳幔混合的特点。通过构造判别,反映达达肯乌拉山岩体可能形成于俯冲陆壳断离、幔源岩浆底侵的地球动力学背景,在中央造山带早中生代统一的板块碰撞与挤压构造体制下,以滩间山蛇绿岩带为基础,发生陆壳俯冲和断离作用,并诱发幔源岩浆的底侵和下地壳物质的部分熔融,沿火山机构侵位形成达达肯乌拉山岩体。  相似文献   

天然气化探异常机理探讨及其在勘探中的意义     

张彦霞  荣发准  赵克斌 《安徽地质》2001,11(3):215-219

天然气在地质体中运移过程中留下示踪痕迹，通过化探的方法，结合地质、地球物理方法，确定近地表地球化学效应或井下地球化学效应，为油气的进一步勘探提供地质资料和参考价值。  相似文献   

Ar-Ar geochronology of Late Mesozoic volcanic rocks from the Yanji area, NE China and tectonic implications   总被引：2，自引：0，他引：2  

LI ChaoWen    GUO Feng  FAN WeiMing & GAO XiaoFeng  Key Laboratory of Marginal Sea Geology  Guangzhou institute of Geochemistry  Chinese Academy of Sciences  Guangzhou  China  Graduate University of the Chinese Academy of Sciences  Beijing  China 《中国科学D辑(英文版)》2007,50(4):505-518

Ar-Ar dating results of late Mesozoic-Cenozoic volcanic rocks from the Yanji area, NE China provide a new volcano-sedimentary stratigraphic framework. The previously defined “Triassic-Jurassic” volcanic rocks (including those from Sanxianling, Tuntianying, Tianqiaoling and Jingouling Fms.) were erupted during 118―106 Ma, corresponding to Early Cretaceous. The new eruption age span is slightly younger than the main stage (130―120 Ma) of the extensive magmatism in the eastern Central Asian Orogenic Belt and its adjacent regions. Subduction-related adakites occurring in the previously defined Quanshuicun Fm. were extruded at ca. 55 Ma. Based on these new Ar-Ar ages, the late Mesozoic to Palaeocene volcano-sedimentary sequences is rebuilt as: Tuopangou Fm., Sanxianling/Tuntianying Fm. (118―115 Ma), Malugou/Tianqiaoling Fm. (K1), Huoshanyan/Jingouling Fm. (108―106 Ma), Changcai Fm. (K2), Quanshuicun Fm. (~55 Ma) and Dalazi Fm. Our results suggest that subduction of the Pa- laeo-Pacific Ocean beneath the East Asian continental margin occurred during 106 to 55 Ma, consistent with the paleomagnetic observations and magmatic records which indicated that the Izanagi-Farallon ridge subduction beneath the southwestern Japan took place during 95―65 Ma.  相似文献   

Farmland marginalization in the mountainous areas:Characteristics,influencing factors and policy implications   总被引：5，自引：1，他引：4  

SHAO Jing'an  ZHANG Shichao  LI Xiubin 《地理学报(英文版)》2015,25(6)

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Evaluating the Bonn—Marrakesh agreement     

《Climate Policy》2013,13(1):111-117

Abstract

This article evaluates the environmental effectiveness and economic efficiency of the Kyoto Protocol after the Bonn Agreement and the Marrakesh Accords. The US withdrawal has by far the greatest impact in reducing the environmental effectiveness, lowering the price of traded emission permits and reducing Annex I abatement costs. The decisions on sinks imply that the Annex I CO₂-equivalent emissions without the US will come out at about 1/2% below base-year level, instead of over 4% below base-year level. Without US participation, the emission permit price is estimated to be low. Therefore, banking hot air by Russia and the Ukraine is of absolute importance for the development of a viable emissions trading market, and would also enhance the environmental effectiveness of the Kyoto Protocol.  相似文献   

湖泊沉积物年纹层的研究方法及其意义   总被引：12，自引：4，他引：8  

刘强  游海涛  刘嘉麒 《第四纪研究》2004,24(6):683-694

文章总结了前人对湖泊沉积物年纹层类型的划分,并根据年纹层的形成过程和组分特征分为3个大类,即碎屑年纹层、生物成因年纹层(如硅藻年纹层等)和化学成因年纹层(如方解石年纹层、菱铁矿年纹层、黄铁矿年纹层、蒸发盐年纹层等)。介绍了目前应用于湖泊沉积物年纹层研究的主要方法和技术包括:1)新鲜沉积物表面照相、X射线照相技术;2)光学显微镜观察;3)数字化图像分析;4)扫描电子显微镜技术等。而岩相学大薄片是目前年纹层研究工作中应用非常广泛的材料,对目前制作大薄片比较普遍采用的快速冷冻-冷冻干燥和水-丙酮-环氧树脂交换这两种方法进行了介绍并比较了各自的优劣。湖泊沉积物年纹层研究的古环境意义主要体现在两个方面,一是提供了高精度的纹层年代学时间标尺,在诸如气候突变事件的时限、大气¹⁴C浓度变化、火山灰层定年、古地磁场长期变化主曲线重建等方面有重要意义;二是年纹层性质研究如年纹层厚度和年纹层微相变化本身所蕴藏的高分辨率古气候环境变化信息,在太阳活动周期、ENSO等气候事件的研究中也有重要意义。最后,文章简单介绍了我国东北龙岗火山区四海龙湾玛珥湖沉积物中年纹层的特征并展望了其研究潜力。  相似文献   

东天山同成铅矿地球化学特征及找矿意义     

任燕  颉勇 《新疆地质》2019,(3):313-317

同成地区位于东天山阿齐山-长城山岛弧带(觉罗塔格岛弧),南部有彩霞山铅锌矿,东部有红柳沟铜铅锌多金属矿及维山铅锌矿等。该地区处于新疆重要的铜、镍、金等多金属成矿带,是新疆重要成矿带,成矿条件有利。研究区内元素异常受地层控制明显,主成矿元素Pb、Zn富集度高、范围广,且元素异常整体重叠,所圈定的化探异常与地表发现的铅矿化带走向一致。根据目前取得的化探及找矿成果,认为同成地区具有寻找新型铅矿的较大潜力。  相似文献