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1.
水城赫章铅锌矿成矿的金属物源研究   总被引:8,自引:0,他引:8  
黔西北各岩石地层单元铅锌背景含量,沉积旋回,水城赫章主要铅矿矿床的含矿层,近矿围岩,矿石矿物稀土元素和铅同素研究表明;玄武岩,8辉绿岩并非本区铅锌矿源岩(层),铅主要来源于玄武岩下伏的沉积岩。成矿铅的成因主要是壳源铅,其次是造山带铅,深海沉积的凝缩段是Zn及部分pb的矿源层;玄武岩之下各沉积旋回下部的碎屑岩一般铅锌背景值高,也可能为成矿提供物源。  相似文献   

2.
二叠纪是中国南方火山活动较为强烈的时期之一,此时贵州省境内形成了大面积的玄武岩。文章通过岩石学、地球化学、大地构造学研究论证了早二叠世玄武岩喷发时为大陆裂谷环境,从宏观、微观岩石学特征确定了分布区东部的早二叠世玄武岩为海底喷发的产物,并详细研究了它对古海洋沉积学、古海洋地球化学的影响。  相似文献   

3.
F Fischer  W Zillig  K O Stetter  G Schreiber 《Nature》1983,301(5900):511-513
Several types of extremely thermophilic archaebacteria have recently been isolated from solfataric water holes, hot springs and hot sea floors. It has been shown that some of them can live using sulphur respiration of reduced carbon substrates as a source of energy, a type of metabolism previously described for the eubacterium Desulfuromonas. We report here that several extremely thermophilic archaebacteria can live with carbon dioxide as their sole carbon source, obtaining energy from the oxidation of hydrogen by sulphur, producing hydrogen sulphide. They are thus capable of a new type of anaerobic, purely chemolithoautotrophic metabolism, a possible primaeval mode of life.  相似文献   

4.
封闭体系中水与玄武岩作用的研究   总被引:3,自引:0,他引:3  
玄武岩与水的作用主要表现在硅酸盐及铝硅酸盐矿物的水解作用。本文首先从理论上论述硅酸盐及铝硅酸盐矿物的界面反应过程。然后结合水─岩作用实验,探讨水与玄武岩在封闭条件下的作用特点及其动力学机制。为模拟自然界中深部封闭体系地下水与玄武岩的作用,我们将采自六合玄武地区的上第三系上新统黄岗组(N2H)碱性徽榄玄武岩粉碎后分别与具不同酸碱性的水溶液密封于塑料瓶中,分析其封闭条件下浸泡不同时间后水溶液的化学组成,探讨玄武岩与水的作用规律。研究结果表明:(1)封闭体系中水与玄武岩作用,水溶液的pH值普遍增高;在初始环境为酸性条件下,水中可溶性SiO2含量呈对数曲线变化,在弱酸性、中性及碱性条件下,则呈抛物线状变化;水─岩作用过程中元素释放规律亦随条件不同而不同。(2)控制硅酸盐及招硅酸盐矿物水解反应速度的化学反应速度和弥散速度,在酸性条件下,前者占主导作用,在弱酸性、中性和碱性条件下则是弥散速度控制了水解反应速度。最后,本文将理论推导出的矿物水解反应速度方程与水─岩作用实验结果相比较,并绘出拟合图形,表明理论与实际相吻合。  相似文献   

5.
架底金矿为产于茅口组与玄武岩组第一段之间的构造蚀变体(Sbt)中和峨眉山玄武岩第二段凝灰质玄武岩内的原生金矿床,是贵州西南部地区近年来发现的一种特殊的卡林型金矿床.通过野外观察和光薄片镜下鉴定,对架底金矿的矿石类型、矿石矿物组合、矿石结构构造及围岩蚀变特征的研究表明:呈半自形-他形结构、浸染状构造的黄铁矿与金矿的关系最为密切;硅化、黄铁矿化及毒砂化是寻找金矿的主要蚀变标志;凝灰岩和构造蚀变体(Sbt)是该区金的主要找矿标志.本文系统总结了矿石的基本特征及蚀变标志,以期对其周边区域找寻同类型金矿具有借鉴意义.  相似文献   

6.
金湖凹陷闵桥构造阜宁组烃源岩中发育玄武岩,并且形成了玄武岩一烃源岩组合体。对阜宁组烃源岩中的微量元素系统分析发现,在生油门限深度附近,玄武岩被周围烃源岩有机质形成的有机酸蚀变改造,其中的微量金属元素被活化、溶蚀和迁移,然后沉淀于烃源岩中。其结果造成玄武岩原生气孔和收缩裂缝进一步扩大和连通,形成了良好的储集空间;同时周围烃源岩中微量金属元素含量显著增加。这种元素迁移是导致玄武岩蚀变、储集性能改善的重要原因,这也使有机质热演化得到某些过渡金属的催化作用成为可能。  相似文献   

7.
Knauth LP  Burt DM  Wohletz KH 《Nature》2005,438(7071):1123-1128
Mars Exploration Rover Opportunity discovered sediments with layered structures thought to be unique to aqueous deposition and with minerals attributed to evaporation of an acidic salty sea. Remarkable iron-rich spherules were ascribed to later groundwater alteration, and the inferred abundance of water reinforced optimism that Mars was once habitable. The layered structures, however, are not unique to water deposition, and the scenario encounters difficulties in accounting for highly soluble salts admixed with less soluble salts, the lack of clay minerals from acid-rock reactions, high sphericity and near-uniform sizes of the spherules and the absence of a basin boundary. Here we present a simple alternative explanation involving deposition from a ground-hugging turbulent flow of rock fragments, salts, sulphides, brines and ice produced by meteorite impact. Subsequent weathering by intergranular water films can account for all of the features observed without invoking shallow seas, lakes or near-surface aquifers. Layered sequences observed elsewhere on heavily cratered Mars and attributed to wind, water or volcanism may well have formed similarly. If so, the search for past life on Mars should be reassessed accordingly.  相似文献   

8.
早古生代海相碳酸盐的成岩蚀变性及其对海水信息的保存性   总被引:18,自引:1,他引:18  
有关海相碳酸盐对海水信息保存性的评估研究近年来得到了越来越多的重视,已成为古海洋学研究一个不可缺少的重要前提,其发展对古海洋学及其他相关学科研究水平的提高至关重要,通过对重庆市秀山剖面早古生代海相碳酸盐的阴极发光性和Mn,Sr,Fe,Mg等元素分析,评估了早古生代层中各种碳酸盐结构组分对海水信息的保存信息的保存性及主要控制因素。除细结构的微晶方解石和腕足类壳对海水信息保存较好以外,白云石,尤其是微-粉晶白云石对海水信息的可保存性也得到肯定,在控制碳酸盐矿物成岩蚀变性的因素中,除要注意其原始矿物是否具有较高的抗成岩蚀变能力外,同时要注意岩石原生孔隙度和岩石中陆源碎屑含量对碳酸盐岩蚀变的影响,作者还强调了成岩过程中由长石等铝硅酸溶解提供壳源Sr所造成的碳酸盐矿物成岩蚀变可能表现为较高的Sr含量,这是将Sr含量作为评估方法时需要注意的,在不进行^87Sr/^86Sr测定的前提下,Mn/Sr比值可弥补这方面的不足。  相似文献   

9.
Extreme crustal oxygen isotope signatures preserved in coesite in diamond   总被引:3,自引:0,他引:3  
Schulze DJ  Harte B  Valley JW  Brenan JM  Channer DM 《Nature》2003,423(6935):68-70
The anomalously high and low oxygen isotope values observed in eclogite xenoliths from the upper mantle beneath cratons have been interpreted as indicating that the parent rock of the eclogites experienced alteration on the ancient sea floor. Recognition of this genetic lineage has provided the foundation for a model of the evolution of the continents whereby imbricated slabs of oceanic lithosphere underpin and promote stabilization of early cratons. Early crustal growth is thought to have been enhanced by the addition of slab-derived magmas, leaving an eclogite residuum in the upper mantle beneath the cratons. But the oxygen isotope anomalies observed in eclogite xenoliths are small relative to those in altered ocean-floor basalt and intermediate-stage subduction-zone eclogites, and this has hindered acceptance of the hypothesis that the eclogite xenoliths represent subducted and metamorphosed ocean-floor basalts. We present here the oxygen isotope composition of eclogitic mineral inclusions, analysed in situ in diamonds using an ion microprobe/secondary ion mass spectrometer. The oxygen isotope values of coesite (a polymorph of SiO2) inclusions are substantially higher than previously reported for xenoliths from the subcratonic mantle, but are typical of subduction-zone meta-basalts, and accordingly provide strong support for the link between altered ocean-floor basalts and mantle eclogite xenoliths.  相似文献   

10.
Madden ME  Bodnar RJ  Rimstidt JD 《Nature》2004,431(7010):821-823
The Mars Exploration Rover Opportunity identified the ferric sulphate mineral jarosite and possible relicts of gypsum at the Meridiani Planum landing site. On Earth, jarosite has been found to form in acid mine drainage environments, during the oxidation of sulphide minerals, and during alteration of volcanic rocks by acidic, sulphur-rich fluids near volcanic vents. Jarosite formation is thus thought to require a wet, oxidizing and acidic environment. But jarosite on Earth only persists over geologically relevant time periods in arid environments because it rapidly decomposes to produce ferric oxyhydroxides in more humid climates. Here we present equilibrium thermodynamic reaction-path simulations that constrain the range of possible conditions under which such aqueous alteration phases are likely to have formed on Mars. These calculations simulate the chemical weathering of basalt at relevant martian conditions. We conclude that the presence of jarosite combined with residual basalt at Meridiani Planum indicates that the alteration process did not proceed to completion, and that following jarosite formation, arid conditions must have prevailed.  相似文献   

11.
两广交界处的岑溪二叠纪岛弧型玄武岩是华南地区(狭义)首次报道的、有较为可靠同位素年龄的晚古生代活动大陆边缘型玄武岩。对该地区玄武岩和细碧角斑岩的主量元素、微量元素(包括稀土元素)和同位素年代学进行了综合研究,论证了岑溪细碧角斑岩建造是与古特提斯域大陆边缘岛弧或弧间盆地有关的二叠纪火山喷发产物。  相似文献   

12.
In this study, the bacterial community structures in samples of ballast water collected from a ship from Singapore and of local sea water collected from Xiamen Port were compared using restriction fragment length polymorphism (RFLP) and 16S rDNA sequence analysis. Except for dominant α-Proteobacteria that are common to both systems, the bacterial community structures of the two systems were quite different. Most of the clones derived from the different systems were grouped into different phylogenetic clusters, and the sys-tems share only one common RFLP pattern. The ballast water, which is likely from clean offshore waters, contains sequences specific to α- and γ-Proteobacteria. Phylogenetic analysis revealed that the ballast water contained sequences belonging to attached bacteria and bacteria commonly found in the open sea, as well as many novel sequences. In addition, no known pathogenic bacteria were detected in the ballast water samples. Conversely, water samples from Xiamen Port were apparently affected by the near shore environments.Specifically, in addition to α- and γ-Proteobacteria, water from Xiamen Port contained β- and δ-Proteobacteria, Synechococcus, Bacter-oidetes and Actinobacteria, which are common in coastal environments. Additionally, four pathogenic bacterial sequences and one plas-mid sequence of a potential red tide forming alga were detected in the water from Xiamen Port, which suggests that the local sea water is polluted. The results of this study can be used as background information to assess the risk associated with the introduction of non-indig-enous species to local systems and to establish ballast water management systems.  相似文献   

13.
水-岩作用模型及其在水-玄武岩反应研究中的应用   总被引:1,自引:0,他引:1  
采用线性规划的方法模似地下水与岩石之间的作用,计算地下水与岩石之间的矿物溶蚀量是水-岩作用研究的一个新方法.本文以江苏六合玄武岩地区水-岩作用研究为例讨论了水一岩作用模型的应用,并对其目前仍存在的问题进行了探讨.  相似文献   

14.
用大米草和互花米草创新水利工程   总被引:1,自引:0,他引:1  
建议用大米草和互花米草创新水利工程,包括:促淤造陆,与海争地;消浪抗风,保滩护岸;保持水土,遏制流失;护港减淤,便利航船;降低污染,改善环境;米草水工,相互促进;舟状草滩,飘现水面。其中有些已经实现了多年,其余的则尚待试验、实施。上述设想的实现将会带来巨大的经济、社会和生态效益。  相似文献   

15.
The hydrologic cycle in deep-time climate problems   总被引:5,自引:0,他引:5  
Pierrehumbert RT 《Nature》2002,419(6903):191-198
Hydrology refers to the whole panoply of effects the water molecule has on climate and on the land surface during its journey there and back again between ocean and atmosphere. On its way, it is cycled through vapour, cloud water, snow, sea ice and glacier ice, as well as acting as a catalyst for silicate-carbonate weathering reactions governing atmospheric carbon dioxide. Because carbon dioxide affects the hydrologic cycle through temperature, climate is a pas des deux between carbon dioxide and water, with important guest appearances by surface ice cover.  相似文献   

16.
Historically,studyontheseasurfacehasbeen restrictedbasicallytothecontentofthemixedlayer ofthewatercolumnandtotheseasurfacedynamics.Lessattentionhasbeenpaidtotheair waterinter face,whichisconstitutedbythefirstfewtensofmi cronsanddefinedastheseasurfacemicrolayer(SM)[1].SMisanimportantboundarybetweenat mosphereandtheocean,asanareaofexchanging matterandenergy.TheSMplaysakeyroleinthe globalbiogeochemicalcyclebecauseallgaseous,liquid andparticulatematerialsmustpassthroughthisinter facebetweentheoc…  相似文献   

17.
Characteristics of the zooplankton community inhabiting the sea surface microlayer (SM) and the sub-surface microlayer (SSM) are compared at six sampling stations in Daya Bay, near Shenzhen City of China during 2 cruises in 1999. This is the first study on zooplankton community in the SM in China. Results show that protozoans and nauplii are the most dominant components, accounting for 80.71% (SM) and 89.15% (SSM) of the total zooplankton in the average abundance, respectively. The densities of copepods (adult + copepodid) are higher in the SSM than in the SM. The size-frequency distributions indicate that the frequency of micro-zooplankton (<0.2 mm) is higher in the SM (0.8235, n=290) than in the SSM (0.6768, n=306). Enrichment phenomenon of zooplankton is detected in the SM at the sampling stations excluding two stations near nuclear power plants (NPP). The enrichment factor is from 1.516 to 3.364 with the average value of 2.267. The SM zooplankton community structure revealed in the present study is quite different from previous investigations in the Bay. Typical sea water characteristics such as turbidity, biological oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and chlorophyll a (Chl-a) indicate that the water quality is poorer in the SM than in the SSM.  相似文献   

18.
安固里淖补给区岩性多为玄武岩或花岗岩。受地貌、岩性、构造、多期喷发旋回层、古风化壳和下伏碎屑岩层等多因素制约,玄武岩或花岗岩含水层富水性差异大,整体为贫乏,制约了张北县贫困区人民群众的生产生活。本文通过大比例尺地面调查、物探解译、钻探验证等手段,基于基岩山区蓄水构造概念,总结分析了安固里淖流域补给径流-侵蚀型、补给径流-接触型、断裂带集水蓄水型、含水岩组蓄水型四种地下水赋存类型。在玄武岩区采取以瞬变电磁法(TEM)为主,高密度法等为辅的勘探方法,找水的目标层位为砂砾岩和裂隙孔洞发育的玄武岩,二者在视电阻率上相比泥岩反映为次高阻和高阻。在花岗岩区采用电法勘查构造裂隙较为适合,目标层位为电阻率陡降段的线性构造区。通过地下水勘察实例,确定了玄武岩风化裂隙孔洞水、岩浆岩构造裂隙水、风化壳等层间裂隙水、碎屑岩孔隙裂隙水4个找水方向及适宜的开采方式。本文可为岩浆岩缺水区应急找水提供找水靶区与勘探方法参考。  相似文献   

19.
涠洲岛地貌与第四纪地质特征   总被引:6,自引:1,他引:6       下载免费PDF全文
涠洲岛是第四纪玄武岩岩浆喷发时在水下堆积而形成的。该岛构造上受东北、西北、东南向断裂的控制,地形南高北低.据分析,南湾是本岛南部被侵蚀破坏后的古火山口残迹,另一火山口位于岛西横路村西北。岛屿地貌特征为南侵北堆,南部从石盘滩向南绕南湾港至西岸海蚀地貌比较发育,常见的有海蚀崖、海蚀洞、海蚀柱、海蚀平台等.北端从横岭向西北转西南到后背塘,海成沙堤十分发育。沙堤呈牛轭状分布,长71cm,宽100~450m,按形态、结构把沙堤分新、老沙堤,老沙堤高6~12m,由于长期吹扬作用,已改变原状,形成凹凸不平砂丘;新沙堤内缘与老沙堤接触且覆盖于老沙堤之上.高2~4m.岛的沿岸珊瑚岸礁相当发育,特别是在北、东部发育最好,南、西部较差.珊瑚岸礁最重要特征是礁源碳酸盐和陆源碎屑的混合沉积作用.其珊瑚礁的形成于3100年前。涠洲岛出露的地层最老的是玄武岩,主要分布于东北海滩,北部及南部沿岸零星露头。其次为火山碎屑岩,火山碎屑岩构成岛屿主体。本岛自第四纪以来、火山活动经历过三个喷发旋回、五次喷发。  相似文献   

20.
长白山地区玄武岩地下水资源及天然饮用矿泉水资源具有广阔的开发利用前景。本文对玄武岩地下水基本特征从空隙类型、富集规律、补径排条件、水资源及矿泉水资源等方面进行了初步研究。  相似文献   

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