Paleomagnetic Data and Dyke Swarms Geometries – Important Tools for Precambrian Paleogeographic Reconstructions

正There are only two quantitative tools for Precambrian paleogeographic reconstructions–paleomagnetic data and dyke swarms geometries.Paleomagnetic data provide information about paleolatitudes and orientation of rigid     

干式集尘器

所叙述的集尘器的特点是装备有铰链式吸尘罩.罩的下部放有带口的棱形箱以便大     

MIGRATION OF GEOSYNCLINES

The term geosyncline was applied by J. D. Dana in 1873 to the long earth trough in which he conceived that the strata now involved in the folds of the Appalachian Mountains of eastern North America were deposited. He extended this term to include all similar earth troughs, whether simple or complex, which are iormed in regions of excessive deposition. Such earth     

皮尔巴拉地块的地壳演化

皮尔巴拉地块位于澳大利亚西北部,面积60,000平方公里,这里有一些世界上最老的(3500Ma)并且出露最好的太古宙岩层。花岗岩形成了100公里宽的卵形岩基,构成该地块约60％,可分为三种主要类型:1)混合岩,片麻岩和叶片状石英二长岩,花岗闪长岩和钠质花岗岩,年龄从至少3400Ma到约2900Ma。2)不同年龄的叶片状斑状石英二长岩和花岗闪长岩,但以3000Ma的为主。3)年龄为2700—2600Ma的构造运     

英国诺福克北部布尔河上游白垩和冰碛物含水层稳定同位素研究

<正> 前 言 最近两年中,我们研究了英国诺福克北部布尔河上游白垩系的白垩和上覆第四系冰碛物含水层中地下水的地球化学演变。为了进一步弄清水文地质条件和水文地球化学演变之间的关系,我们研究了该区地下水中的稳定同位素水文地球化学特征。 研究区位于东经1°—1°14′和北纬52°47′—54′(图1)面积为80平方公里。上白垩系的白垩层厚达450米,上复着第四系漂砾粘土和砂砾石冰碛物,其厚度达40—45米。      

保压取样钻具内岩心温压采集器的研制与应用

在绳索取心钻探过程中,井底温度与压力的实时测量,有助于改进取心工艺,提高岩心采取率;同时岩心在井底的原位测量数据对于了解岩心的物理特性有着重要意义,这一点在海域天然气水合物勘探中尤为明显。本文主要介绍了一种内置于保压取样钻具中的温压采集器的结构及其工作原理。该采集器采用干电池供电,单次工作时间>72 h,能够采集与存储整个取样过程中岩心管内的温度与压力参数,与电脑端连接后就能得到全部数据。通过搭载海洋地质十号钻探船,该采集器完成了一个回次的海试试验,得到了整个绳索取心钻进过程的温度与压力数据。经过分析,收集到的数据与实际取心工艺过程相符,数据平稳可靠。     

西澳大利亚纳里耶片麻岩杂岩的高敏度质谱分辨离子探针U-Pb锆石地质年代学

澳大利亚伊尔岗克拉通的纳里耶片麻岩杂岩的高敏度质谱分辨离子探针(SHRIMP)U-Pb锆石地质年代学已经进一步证明。该区的东半部含有丰富的早太古代片麻岩(3300-3730Ma),而且在其西半部发现了只有3000Ma或小3000Ma的片麻岩。在研究程度较高的纳里耶片麻岩杂岩的南部地区,早太古代片麻岩被划分为埃乌拉达(Eurada)片麻岩组合(最老的岩石为3490Ma)和努卡瓦拉片麻岩组合(最老的岩石为3730Ma)。在这两个组合中,只有最老的岩石是英闪质的,而所有较年轻的岩石是花岗闪长质或花岗质的。这两个组合,虽然构造上可能并列在一起,但直到发生3280-3300Ma的花岗岩和伟晶岩侵位为止,却表现为不同的演化历史。人们发现这两个片麻岩组合与纳里耶上壳岩组合呈互层,上壳岩组合含有丰富的富含石英的碎屑沉积岩。该岩石组合的最大露头形成了纳里耶山和杰克山(Jack HilIs),该区沉积物内少部分碎屑锆石年龄>4000Ma。碎屑锆石年龄数目(Populations)在纳里耶上壳岩组合中因样品而异。这些年龄数目的分析表明,除去3800—4280Ma的锆石因物源尚不知道外,其它碎屑锆石均以不同比例来源于努卡瓦拉和埃乌拉达片麻岩组合岩石。早太古代片麻岩组合之间的原始关系,由于几期花岗岩岩席的侵入作用,其与纳里耶上壳岩呈夹层以及2750Ma和2620Ma之间的褶皱,之后又伴随有太古宙末期或元古宙的近垂直剪切带运动,而面目全非。晚太古代事件与整个伊尔岗克拉通的事件完全相似,并且认为可能在几个不同的幕中通过地体组合伴随着克拉通的增长。     

Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts.     

Study on Liquefying Simulation Test of Retaining Structure Ground of Kobe Port

ＩＮＴＲＯＤＵＣＴＩＯＮＯｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｔｏｐｉｃｓｉｎｅａｒｔｈｑｕａｋｅｇｅｏｔｅｃｈ－ｎｉｃａｌｅｎｇｉｎｅｅｒｉｎｇｉｓｔｈｅａｓｅｉｓｍａｔｉｃｄｅｓｉｇｎｏｆｅａｒｔｈ－ｒｅｔａｉｎｉｎｇｓｔｒｕｃｔｕｒｅｓ（Ｈ...     

碱性岩中新矿物的比较晶体化学

在科拉半岛和北乌拉尔的碱性岩中近来发现了五种新矿物.莫斯科大学结晶学系在近三年的时间里测定了这些矿物的结构.本篇评论概述了这些矿物的结构测定结果.Grumantite(Na[Si_2O_4(OH)].H_2O),产于Lovezero碱性岩块,其结构中存在一种新型的间断骨架,这种骨架是四面体络合基(T_2O_5)的非典型的结构形式.它的形式与(OH)-基的存在有关,羟基使得每个配位四面体内的平均负电荷减少.Clinobehoite[Be(OH)_2],产于北乌拉尔的脱硅伟晶岩内,与其他Be矿物:硅铍钙石、锂铍脆云母及富铁高岭石共生.它的结构由三层Be四面体层组成的结构单元层之间以氢键相连而构成.在Clinobehoite的红外光谱中明确地揭示出不同类型的氢键的存在.