南部非洲的花岗片麻岩—绿岩地盾     

C.R.Anhaeusser  J.F.Wilson  李上森 《华北地质》1982,(4)

前言构成南部非洲地盾一部分的早前寒武纪(太古宙)花岗岩一绿岩层,是地球表面上已知最老的地层之一。在博次瓦纳东部、南非(阿扎尼亚)东北部以及津巴布韦,该地盾是由林波波活动带分割的两个克拉通、即卡普瓦尔和罗德西亚克拉通组成。在时间上从27—35亿年(或甚至更老)的地区,是作为30亿年前在大陆边缘条件下形成的一种独特的克拉通盆地基底。  相似文献   

关于“早些相对于晚些”发布地震预报的讨论     

L.B.尼尔森  D.C.尼尔森  刘晓辉  陈彭年 《国际地震动态》1983,(4)

文章介绍了日本地震学会1982年秋季大会简况,会上共宣读241篇论文,包括八个方面;本文重点介绍了有关地震活动与地震预报研究两方面的内容。  相似文献   

陆地卫星数字图象分析在区域地质凋查中的应用     

C·J·辛普森  刘建国 《地质科技情报》1983,(1)

矿产资源局(BMR)的地质学家们在最初获得陆地卫星影象之后即开始尝试在野外地质研究中将它作为航摄片的辅助手段使用。用传统航片解译方法来解译陆地卫星影象,其效果取决于影象质量和研究对象的特征。BMR野外研究中会遇到各种各样的地质问题,并表现为各种各样的地貌环境特征,诸如巴布亚新几内亚和伊里安查亚的森林,澳大利亚内陆的沙漠以及南极冰盖。  相似文献   

昆士兰州艾萨山镇铜矿石形成物中先存硫化物的作用     

C·W·Robertson  赵经中 《华北地质》1983,(4)

昆士兰州西北部的艾萨山镇硫化物矿床,产在已变质成低级绿片岩相的,并在热液活动影响下发生不同程度蚀变的粉砂岩—页岩层序中。形成铅—锌—银矿体的方铅矿和闪锌矿以及细粒黄铁矿,与这些沉积物成互层;而黄铜矿矿化看来已迭加于其上。在最大的矿体-1100矿体中,有一个高品位的块状黄铜矿核,产在黄铁矿矿化强烈的同一层位上;这个核随着黄铁矿的富集而缩小。钴矿物与黄铜矿矿石密切伴生,并表现出与上述情况相同的关系。黄铜矿与黄铁矿的硫同位素值的变化范围相同,表明硫的来源是共同的。黄铁矿层中硫的丰度,并不随着铜品位的增长而增加。这些因素证实组成黄铜矿和富钴硫化物所必需的硫,来自先存地层层序的观点。硫的这种来源,控制了铜、二氧化硅和钴从矿化溶液中的沉积,并为解释铜与铅—锌—银矿石的空间关系提供了联系。  相似文献   

Clostridium perfringens as a potential indicator for the presence of sewage solids in marine sediments     

Skanavis C  Yanko WA 《Marine pollution bulletin》2001,42(1):31-35

Marine sediment cores collected from several depths of water and distances from a California sewage outfall were tested to see if sediments influenced by sewage solids were a reservoir of enteric pathogens, and if concentrations of indicator bacteria were related to the presence of sewage solids. Vertical distributions of microorganisms in marine sediments were determined; there was a decrease of indicator bacteria with increasing sediment depth. Aeromonas was randomly isolated, but none of the enteric bacterial pathogens or viruses were detected. While classic indicator bacteria were of little value in predicting the presence of pathogens, or relative amounts of sewage solids, Clostridium perfringens may be a suitable indicator. Clostridium perfringens concentrations were not related to the presence of pathogens in sediments.  相似文献   

Northern ocean inventories of organochlorine and heavy metal contamination     

Crane K  Galasso J  Brown C  Cherkashov G  Ivanov G  Petrova V  Vanstayan B 《Marine pollution bulletin》2001,43(1-6):28-60

  相似文献   

The main issues affecting coasts of the Indian and western Pacific Oceans: a meta-analysis from Seas at the Millennium     

Sheppard C 《Marine pollution bulletin》2001,42(12):1199-1207

A review of the world oceans in three volumes by 365 scientists, provides scope for several ‘meta-analyses' of the main problems affecting over 100 areas in the year 2000. This article summarises the main issues affecting a sub-set of the reviewed areas, covering Asian, African and Arabian countries dealt with in Volume 2, which included over 50 articles. From all issues raised, assessment is made of the nature of the major ones, including evaluation of reasons why so many of them remain important issues after so much attention to them. These include long standing problems, several problems more newly flagged as becoming particularly important, the issue of global warming and no less than three related issues connected with fishing and over exploitation. One or two issues such as industrial pollution and sewage, previously considered of almost universal concern, almost traditional pollution issues even, continue to feature strongly for some countries, but while these were almost always referred to in Seas chapters, by and large these categories appear not to be the most pressing of issues today, except in localized areas (albeit areas where huge numbers of people live). Perhaps other issues have simply taken over. They are excluded from this article.  相似文献   

Paleozoic Accretion-Collision Events and Kinematics of Ductile Deformation in the Eastern Part of the Southern-Central Tianshan Belt, China   总被引：3，自引：0，他引：3  

J.CHARVET  S.C.LAURENT 《《地质学报》英文版》2002,76(3):308-323

The Tianshan range could have been built by both late Early Paleozoic accretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture is marked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphic relics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanic arc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along with unconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation. The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductile shearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductile deformation, and the later deformation, a dextral strike-slip tectonic process, occurred during the Late Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably on pre-Carboniferous metamorphic and ductilely sheared rocks, implying t  相似文献   

中国西南天山山前的晚新生代构造与地震活动   总被引：40，自引：0，他引：40  

陈杰  曲国胜  尹金辉  Burbank D.W  Scharer K  Rubin C  Sobel E  丁国瑜  赵瑞斌  沈军 《中国地震》2001,17(2):134-135

天山是研究现今陆内造山作用及过程、陆内变形、陆内强震及其预测等大陆动力学问题的理想实验场。西南天山和塔里木之间的新生代褶皱－逆断裂带基本上由一南冲弧形推覆构造系统和一向北反冲的构造系统组成，由北而南主要由以下4个运动学单元组成：（1）新生代复活的喀拉铁热克山－天山南脉古生代造山带，其快速变形和抬升可能起始于23－26Ma前，持续至13－16Ma前。（2）向南逆冲的西南天山前陆薄皮主冲断带，包括木兹杜克弧形薄皮推覆体和依柯冲断带，前者代表了向南薄皮逆掩的天山型岩系，地表主要表现为一系列的飞来峰群，在14Ma前曾有过大规模活动，最小缩短量约为20－35km，最小缩短速率为1．4－2．8mm/a；后者代表了向南叠瓦状薄皮逆冲推覆的前陆古生代基底（塔里木地台型沉积岩系）卷入构造，其西段在距今14Ma时曾有过强烈活动。两者共同组成了一复杂的双重构造；新生代地层也卷入变形。（3）喀什－阿图什弧形反冲褶皱－逆断裂带，由3排向北（天山）反冲的左阶雁列展布的第四纪地表滑脱褶皱组成，仅在大山口以西发育。该构造带形成于距今约1．4Ma以后。依什拉克喀拉乌尔断裂以南，博古孜河剖面的最小缩短速率约为5．8mm/a，翁库尔剖面的最小缩短速率约为8．6mm/a。（4）塔里木克拉通下盘块体，向北西方向缓倾，内部变形较小。里木块体西北存在明显的不均匀性，其学问基底高角度逆断裂和走滑断裂控制了盆地新生代沉积的厚度，导致西南天山前陆冲断带的地形地貌、地层、构造变形样式、变形时间以及变形缩短量沿走向的巨大差异性。迈丹－喀拉铁克断裂和阿图什断裂带均为岩石圈规模断裂，研究区的中强地震主要发生在这两条断裂带以及它们之间的西南天山前陆冲断带上。  相似文献   

地倾斜及水文地球化学参数异常与地震活动最佳关系探索     

P．C．伊布纳吉莫夫  My.X.巴吉耶夫 《内陆地震》2001,15(2):175-187

1　ПостановказадачиНадежныйпрогнозвременивозникновенияземлетрясенияможетбытьобеспеченлишькомплексомпрогностическихпараметров. Прогностическаяценностькаждогопараметранеодинакова,какиразличенмеханизмформированияаномальныхэффектоввразличныхполях.Этосоздает…  相似文献