白云鄂博矿区北部韧性剪切带特征及其构造意义

在白云鄂博主矿北西约6.5km处的查干楚鲁一带,有一条近东西向延伸的断层带,前人在该带中部识别出了蛇绿岩混杂堆积。本文作者在蛇绿岩东部的大理岩质糜棱岩中发现鞘褶皱、拉伸线理及旋转碎斑系等变形构造,在大理岩周围发现石英岩型宏观压力影构造,在变质石英砂岩中识别出褶劈理以及方解石脉等相关构造,在这条东西向断裂带北边发现典型的黄铁矿型压力影。根据上述特征判断,查干楚鲁一带为一条近东西向延伸的韧性剪切带,同时具有NEE—SWW向逆左旋走滑的特征。该带揭示出蒙古洋板块与华北板块在晚古生代汇聚拼合的基本格局。     

Morphology and magnetic survey of the Rivera-Cocos plate boundary of Colima,Mexico

The propagation of the Pacific-Cocos Segment of the East Pacific Rise (EPR-PCS) has significantly altered the plate configuration at the north end of the Middle America Trench. This ridge propagation, the collision of the EPR-PCS with the Middle America Trench, the separation of the Rivera and Cocos plates and the formation of the Rivera Transform have produced a complex arrangement of morphotectonic elements in the area of Rivera-Cocos plate boundary, atypical of an oceanic transform boundary. Existing marine magnetic and bathymetric data has proved inadequate to unravel this complexity, thus, a dense grid of total field magnetic data were collected during campaigns MARTIC-04 and MARTIC-05 of the B/O EL PUMA in 2004 and 2006. These data have greatly clarified the magnetic lineation pattern adjacent to the Middle America trench, and have revealed an interesting en echelon, NE-SW oriented magnetic high offshore of the Manzanillo Graben. We interpret these new data to indicate that the EPR-PCS ridge segment reached the latitude (~18.3°N) of the present day Rivera Transform at about Chron 2A₃ (~3.5Ma) and propagated further northward, intersecting the Middle America Trench at about 1.7 Ma (Chron 2). At 1.5 Ma spreading ceased along the EPR north of 18.3°N and the EPR-PCS has since retreated southward in association with a southward propagation of the Moctezuma Spreading Segment. North of 18.3°N the seafloor near the trench has been broken into small, uplifted blocks, perhaps due to the subduction of the young lithosphere generated by the EPR-PCS.     

勉—略混杂岩带构造地质特征与金矿成矿——以陕西省略阳县干河坝金矿床为例

勉略带经历俯冲叠置、碰撞造山和陆内造山3个阶段构造演化过程。即俯冲期深层次褶皱与右行顺层（片）剪切变形、碰撞期中—深层次褶皱递进变形和高角度逆冲剪切变形、后主造山期陆内造山期中—浅层次左行走滑变形和低角度逆冲推覆构造4期不同构造变形。其中前两期构造阶段对金矿成矿产生重要影响。通过对陕西省略阳县干河坝金矿研究认为：俯冲期...     

西非被动大陆边缘重力滑脱构造发育演化及成因机制

西非被动大陆边缘盆地在晚侏罗世伴随大西洋的裂开而形成,陆内裂陷构造旋回(晚侏罗世-早白垩世阿普特期(Aptian))主要发育陆内裂陷构造;过渡期构造旋回(阿普特期)沉积了一套潟湖相塑性层(盐岩);被动大陆边缘构造旋回(早白垩世阿尔布期(Albian)至今)共发育了两期重力滑脱构造,早白垩世阿尔布期-渐新世发育一期(早期)重力滑脱构造,中新世至今发育了另一期(晚期)重力滑脱构造。西非被动大陆边缘同一期重力滑脱构造具有从早到晚由陆向海的前展式发育规律,且多期重力滑脱构造具有从早到晚由陆向海迁移的进积叠加规律。西非被动大陆边缘重力滑脱构造发育的主要控制因素是大地构造背景、地层掀斜、滑脱面形态,其中大地构造背景控制重力滑脱构造体系类型,地层掀斜是引起地质体重力滑脱和变形的根本、控制构造变形的强度,滑脱面形态控制着重力滑脱构造类型和发育位置;次要控制因素是差异重力负载和塑性滑脱层等。并在此基础上建立了宽缓型凹面斜坡和窄陡型斜坡滑脱面下的西非被动大陆边缘重力滑脱构造成因发育模式。     

世界遗产、旅游目的地和农业遗产景观:以加拿大新斯科舍省大草地为例（英文）

加拿大新斯科舍省的大草地是传统土地利用的杰出例子,反映了人类与独特环境相互作用,也因此被联合国教科文组织列入世界遗产名录。大草地不但是加拿大最肥沃的农业景观,还是一个标志性历史遗址,承载着1755年的驱逐阿卡迭人的历史悲剧,吸引了无数游客慕名而来。而今面临着农业的转变和旅游业的衰败双重威胁,人们对大草地于2012年成为世界遗产及其所带来的旅游发展充满期待。本文将大草地作为全球重要农业文化遗产,根据以前的研究,对其成为世界遗产地之后该地区未来经济繁荣和可持续发展的情况进行了探讨。     

Daubechies wavelet coefficients: a tool to study interplanetary magnetic field fluctuations

We have studied a set of 41 magnetic clouds (MCs) measured by the ACE spacecraft, using the discrete orthogonal wavelet transform (Daubechies wavelet of order two) in three regions: Pre-MC (plasma sheath), MC and Post-MC. We have used data from the IMF GSM-components with time resolution of 16 s. The mathematical property chosen was the statistical mean of the wavelet coefficients (〈Dd1 〉). The Daubechies wavelet coefficients have been used because they represent the local regularity present in the signal being studied. The results reproduced the well-known fact that the dynamics of the sheath region is more than that of the MC region. This technique could be useful to help a specialist to find events boundaries when working with IMF datasets, i.e., a best form to visualize the data. The wavelet coefficients have the advantage of helping to find some shocks that are not easy to see in the IMF data by simple visual inspection. We can learn that fluctuations are not low in all MCs, in some cases waves can penetrate from the sheath to the MC. This methodology has not yet been tested to identify some specific fluctuation patterns at IMF for any other geoeffective interplanetary events, such as Co-rotating Interaction Regions (CIRs), Heliospheric Current Sheet (HCS) or ICMEs without MC signatures. In our opinion, as is the first time that this technique is applied to the IMF data with this purpose, the presentation of this approach for the Space Physics Community is one of the contributions of this work.     

基于Pléiades立体影像数字正射影像精度研究

基于Pléiades 1B立体全色影像,采用PCI Geomatic软件进行空三加密,利用RPC有理函数模型和不同像控点进行平差解算,对DOM平面精度和左右像片接边精度进行统计和分析,为后期利用Pléiades立体影像进行1∶10000 DOM生产提供参考。     

新疆萨尔托海石英菱镁岩中发育的韧性剪切带及其对金矿的控制

萨尔托海金矿产在达拉布特蛇绿混杂岩带中。本文首次在该金矿区厘定出韧性剪切带,糜棱岩或者糜棱岩化石英菱镁岩中构成糜棱面理的矿物(铬云母、石英)形成于韧性剪切变形过程中,而切割糜棱面理的方解石-石英-黄铜矿-白云母脉代表脆性变形阶段的流体活动。根据矿物组合相互切割关系,识别出三期构造变形:早期NE向韧性变形(形成铬云母-石英组合)之后,发生了应力方向显著不同的破裂,形成NNW向分布的方解石-石英-黄铜矿-白云母脉;再晚期,应力方向又恢复到NE向,发育了浅层次的脆性构造破坏,形成了白云母-石英细脉。韧性剪切变形向脆性变形转换期间形成了石英-碳酸盐脉,其中往往含硫化物和自然金,此阶段是萨尔托海金矿的主要成矿时期。韧性剪切带控制着萨尔托海地区的金矿分布,成矿作用主要受沿剪切带迁移流体的控制,穿切糜棱面理的方解石-石英-黄铜矿-白云母脉是主要的找矿标志。韧性剪切带对金矿的显著控制表明,韧脆性转换期间形成的含硫化物石英碳酸盐脉以及相伴生的热液蚀变使金富集成矿,矿体一般赋存在断裂构造复杂的膨胀部位。萨尔托海金矿的成因与蛇绿岩的形成和演化没有关系。对韧性剪切带的系统研究是在该地区取得找矿勘探突破的关键。     

新疆南阿尔金木纳布拉克构造混杂岩带物质组成及变形特征

木纳布拉克构造混杂岩带位于南阿尔金与东昆仑衔接部位,是古阿尔金洋岩石圈板块由南向北阶段性俯冲的产物,为南阿尔金蛇绿岩带的重要组成部分。通过1∶10 000大比例尺填图和剖面测量,结合显微尺度的构造解析,对该构造混杂岩带的物质组成和变形特征进行研究,将与构造混杂岩带有关的物质组成划分为弱变形的“岩块”与强变形的“基质”两类,并从中识别出9种不同岩石组合的岩块及2种不同类型的基质。在对“岩块”和“基质”构造几何学和运动学特征研究的基础上,重点分析了地质体的构造变形截切关系及组合特征,在构造混杂岩带中识别出6期变形作用,建立了相对构造变形序列,为木纳布拉克构造混杂岩带演化提供了新的构造证据。     

桂东鹰扬关地区1∶5万区域地质矿产调查成果与主要进展

桂东鹰扬关地区位于钦杭结合带西南段,通过开展该区1∶5万区域地质调查,以国际地层表(2015)为指南,对调查区地层进行了多重地层划分与对比研究。从岩石学、构造学、地球化学角度,对鹰扬关岩群进行了详细研究,明确了其为一套构造混杂岩,通过获得的变质火山碎屑岩锆石LA-ICP-MS U-Pb年龄,认为其主要形成于新元古代。根据岩性特征、野外接触关系及同位素年龄等将区内岩浆岩划分为8个岩体,16个填图单位,获得了各岩体的高精度测年数据,确定了岩浆岩年龄格架;研究了其岩石成因,探讨了岩浆源区以及形成的大地构造背景。建立了调查区构造格架,阐明了构造形成演化历史,划分了构造变形阶段,通过构造解析,于鹰扬关构造混杂岩中识别出5期构造变形,结合区域构造演化确定了相对时序。通过1∶5万水系沉积物测量,查明了1∶5万太保圩幅水系沉积物地球化学特征,编制了元素地球化学图等系列图件。