多次覆盖技术在探地雷达勘探中的应用

多次覆盖技术作为一种增强信号、压制干扰的方法,广泛用于地震勘探工作中,可以大大提高有用信号的信噪比。本文作者把多次覆盖技术引入探地雷达测量工作中,通过与剖面法作对比试验来论证多次覆盖技术在探地雷达勘探中应用的可行性及优缺点。作者根据试验资料总结探地雷达工作中雷达波传播规律、工作参数、资料处理方法,对丰富探地雷达勘探技术作了一次有益的尝试。     

Fine upper crustal structure of Jiashi strong earthquake swarm region in Xinjiang inferred from high resolution seismic refraction profile data

Introduction Jiashi-Artux area in southwest Xinjiang is one of the most active earthquake provinces at pre-sent in Chinese mainland. In the last century, about 3/4 strong earthquakes in Chinese mainland hit this area, and especially from January 21 to April 16 in 1997, 7 earthquakes with the magnituderanging from 6.0 to 6.9 occurred in a very small area of 9 km×18 km near Jiashi (ZHU et al, 1998). It has never taken place before in Chinese mainland that a series of strong earthquakes shoo…     

Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance

Euphotic depth can be defined as the portion of wa- ter column that supports the net primary productivity. Its lower end is the critical depth, namely, the depth measured when the daily net primary productivity is zero[1]. In the ecosystems of oceans, lakes and rivers, phytoplankton live in the euphotic depth and euphotic depth is usually taken as the lower boundary, when studying the primary productivity and biomass of phytoplankton; therefore the corresponding depth is sometimes called the t…     

Wavelet filter analysis of splitting and coupling of seismic normal modes below 1.5 mHz with superconducting gravimeter records after the December 26, 2004 Sumatra earthquake

New generation superconducting gravimeters (SGs), which have been demonstrated to be better than the best seismometers STS-1 at frequencies below 1 mHz, can be accepted as the quietest vertical seismometers for observation of long-period earth free oscillations. Wavelet filtering with narrow band-pass frequency response as shown in this paper is very helpful in removing at- mospheric pressure effects from on gravity records in long-period seismic mode frequency bands. The processing of high quality SG records after the great Sumatra earthquake (Dec. 26, 2004) with wavelet filtering leads to clear observations of all coupled toroidal modes below 1.5 mHz except these for 0T5, 0T7 and 1T1; moreover 1T2 and 1T3 are, for the first time, unambiguously revealed in the vertical components of the free oscillations. The three well-resolved splitting singlets of overtones 2S1 are observed from a single SG record for the first time.     

一次罕见冰雹天气的多普勒雷达回波分析

运用多普勒雷达的基本反射率(R)、风暴相对径向速度(SRM)、垂直积分液态含水量(VIL)等产品,分析了2004年6月20日华北南部罕见的冰雹大风天气过程。结果表明:这次冰雹大风天气过程主要是由超级单体回波中的中尺度气旋引起的;该过程持续时间比较长的原因是“指状”回波和超级单体回波的依次发生、发展。     

阿尔金碰撞造山带西段的构造特征

根据阿尔金山西段前早古生代变质岩的岩石组成、沉积建造、变形变质作用改造历史、岩石地球化学特征等研究,将阿尔金碰撞造山带西段划分为3个构造单元:北阿尔金地块、中阿尔金地块(包括英格里克构造-蛇绿混杂岩带、肖鲁克·布拉克高压变质岩带和塔什萨依玉石矿高绿片岩相-低角闪岩相变质岩带)和南阿尔金地块(包括南阿尔金中-新元古界隆起带和阿尔金南缘复合构造-蛇绿混杂岩带).提出该碰撞造山带经历了前长城纪古陆核形成阶段、长城纪-青白口纪不同基底联合阶段和早古生代洋陆转换阶段3个阶段的构造演化.     

黔西水城—紫云地区晚古生代裂陷槽盆充填和演化

研究了贵州西部古生代发育起来的北西向水城-紫云裂陷槽盆的充填序列和演化.根据地层的岩性特征、接触关系、垂向序列和形成的构造背景等,将该槽盆的充填过程划分为3个序列:深水盆地非补偿沉积到浅海陆棚沉积,是以张裂作用为主的构造作用的产物;槽盆→槽盆边缘→槽盆边缘斜坡(下斜坡)→台缘斜坡,为张裂兼走滑复合构造机制作用下的产物;台缘斜坡环境的海进序列到海退序列,受走滑作用影响明显.根据影响和控制盆地的构造、沉积和岩浆作用等多种因素,将该槽盆的发展演化分为4个阶段:隆起剥蚀阶段、地壳拉伸变薄阶段、断裂沉陷阶段和地幔柱作用阶段.     

昆明地区早寒武世关山动物群研究新进展

总结了昆明地区关山动物群自1999年命名以来开展的研究工作和取得的新进展.简要叙述了关山动物群的研究概况、地层位置、生物群组合特征和关山动物群的研究意义.在关山动物群中首次发现了古虫动物门的Vetulicola gangtoucunensis Luo,Fu et Hu,吐卓虫Tuzoia sp.nov.,古蠕虫Palaeoscolex sp.nov.,腕足类Heliomedusa sp.nov.及三叶形虫、海绵动物新属种.指出关山动物群是一个由多门类软躯体后生动物化石组成的伯吉斯页岩型的动物群,时代介于澄江动物群与凯里动物群(或伯吉斯页岩动物群)之间,起到了承前启后的作用,在寒武纪生命大爆发和寒武纪早期生物演化的研究中有重要意义.     

南京地区新近系含膏砂泥地层的发现及其意义

在进行南京市城市立体地质填图试点工作中,经钻探于仙林大学城发现一套新近系含膏砂泥地层,可与六合灵岩山雨花台组沉积地层对比.该地层的发现对于重新认识南京地区某些相类似断陷盆地基岩面之上的松散覆盖层的结构很有意义,对其在环境地质和工程地质中的影响进行了评述.同时,对地下水参与成矿作用进行了初步论述.     

桂东南云开地区变质杂岩锆石SHRIMP U-Pb年代学

对位于华夏古陆东南部的广西云开地区大面积出露的晚前寒武纪变质杂岩中的主体花岗质片麻岩、中深变质的天堂山岩群石榴辉石岩和中浅变质的云开岩群洋中脊型变质基性火山岩(斜长角闪岩)进行了高精度锆石SHRIMP U-Pb定年.获得天堂山岩群石榴辉石岩的形成年龄为1894Ma±17Ma和1847Ma±59Ma,表明其时代为古元古代;云开岩群洋中脊型变质基性火山岩(斜长角闪岩)的喷发年龄为1462Ma±28Ma,证明该地区存在中(-新)元古代的古洋壳残片;获得花岗质片麻岩的侵入年龄为906Ma±24Ma,应为1000Ma前后发生的全球性Grenville期(四堡期)造山作用的产物,并获得2702Ma±13Ma的继承碎屑锆石年龄,这是云开地区乃至华夏古陆目前获得的最古老年龄,证明华夏古陆曾存在新太古代陆壳物质.