黄河中游及邻区晚新生代地层特征及地表过程讨论

黄河中游及邻区的黄土高原保存着完整的晚新生代风尘堆积序列,断陷盆地和山间盆地中沉积了数千米的河湖相沉积,隆升山系山前地带分布有山麓-洪积相沉积,成因类型齐全,研究历史悠久,是中国北方晚新生代地层研究的重要地区。文章主要依据近30年来各省(区)晚新生代地层最新研究成果,着重阐述了晚新生代地层的主要岩性、厚度、沉积相和分布特征,并通过对不同地区以及不同沉积类型之间的区域地层对比,尝试恢复各时期古地理地貌。古近纪-中新世早中期,区内地势东高西低,中东部总体都是持续抬升、剥蚀和夷平过程;中新世灞河期,区内东、西部发生了构造反转,东部开始接受沉积;上新世-早更新世早期,为内陆湖泊阶段;早更新世晚期-晚更新世早期,南北地形分异,北部仍为内陆湖泊环境,南部黄土加速堆积,内陆湖泊逐渐消亡,河谷下切,堆积阶地发育;晚更新世后期以来,地势高差加大,随着气候变暖,雨量增加,黄河全部贯通,高原北部沙漠化与南部水土流失日趋加剧,以侵蚀作用为主。现代东流入海的黄河水系格局形成可作为内陆湖泊阶段和高原河流阶段的分界,也是黄土从堆积为主向侵蚀为主的转折点。     

一次重要的第四纪构造运动及环境效应

在第四纪早更新世晚期（１．６￣１．０ＭａＢ．Ｐ）,中国大陆陆发生了一次十分强烈的构造活动,造上更新世地层的普遍褶皱和断裂,并有火山活动,同时,这 一次十分重要的造貌运动,它导致了高原面的形成并整体抬升,从而奠定了中国现今地貌格局,这次构造运动地中国环境的影响是十分深刻的,它使大片处于鼎盛时期Ｎ－Ｑ１的古湖消亡,中国现今的主要水系定型,植被分布形式发生变化和气候转型。     

内蒙古额济纳旗地貌特征及其构造、气候事件

根据遥感卫星影像解译及野外地质实地调查,将内蒙古额济纳旗地区的地貌单元划分为中低山区、冲—洪积平原、湖积盆地及风成地貌。根据不同地貌单元组成的沉积物年龄测定和分析,初步认为上新世—早更新世的构造抬升形成苏泊淖尔级湖积阶地;早更新世末(750±60kaBP),发生一次明显的构造抬升活动,形成东、西居延海间的台地;另一次明显的构造抬升记录发生在中更世末—晚更新世初,即149±60kaBP之后,形成黑城冲湖积台地;苏泊淖尔级阶地形成于全新世早、中期,属气候干旱湖泊萎缩形成的气候阶地,阶地沉积物中保存的古风成砂丘,表明晚更新世末—全新世早期气候一度恶化。天鹅湖湖积阶地的形成表明5000a之后一段时间,气候相对适宜;全新世中后期,气候波动强烈,1200aBP出现一次丰水期。     

六盘山晚更新世以来抬升过程沉积响应及环境效应

六盘山构造带夹持于青藏高原与鄂尔多斯地块之间,记录了青藏高原抬升向东北方向推挤的远程效应。关于六盘山抬升过程的研究主要集中在白垩纪及新生代早期,而与人类活动密切相关的晚更新世的研究很少涉及。以盆山响应关系理论为指导,立足于与六盘山相邻的清水河盆地,开展系统的沉积学研究,查明清水河盆地晚更新世的地层序列、沉积充填过程,演绎了六盘山盆地晚更新世以来抬升的过程及其产生的环境效应。研究认为,清水河盆地晚更新世早中期发育2期古湖,以温暖湿润的气候环境为主,晚期由于相邻六盘山的快速抬升,湖水彻底退出了清水河流域,环境逐步开始恶化。晚更新世—全新世清水河流域发育了巨大的六盘山山前冲积扇,该扇体不断沿清水河河谷向东推移,有进一步阻隔清水河形成巨大堰塞湖的趋势。研究成果将为六盘山晚更新世抬升过程研究提供重要依据,为清水河流域的综合治理提供基础地质参考。移动阅读      

对冀北晚更新世地层的新认识

冀北晚更新世地层划分为迁安组与马兰组。迁安组形成于整个晚更新世 ,以河流相沉积为主 ,早期为温暖气候环境 ,晚期为寒冷气候环境 ,可划分为两个生物组合类型。马兰组形成于晚更新世晚期 ,为寒冷干旱气候环境下多种成因形成的一套堆积物     

青藏高原古大湖与夷平面的关系及高原面形成演化过程

青藏高原经过古近纪挤压缩短和增厚地壳均衡隆升,晚新生代形成了以走滑和伸展为主的相对稳定构造环境。中新世早期与晚更新世分别发育巨型古大湖,上新世-早更新世发育很多规模较大的古湖泊,古大湖对夷平面形成演化具有重要的控制作用。中新世早期(（24.1±0.6） ~（14.5±0.5）Ma)以古大湖的湖面为侵蚀基准面,经过隆起区剥蚀夷平和长期湖相沉积,在高海拔环境下形成早期夷平面。中新世晚期-第四纪以湖面与五道梁群湖相沉积顶面为基准,在高海拔环境下继续发生剥蚀夷平和准平原化,逐步形成主夷平面或高原面。第四纪河流溯源侵蚀导致内外流水系分界线自东向西迁移,在青藏高原东部形成高山峡谷地貌。     

大同盆地朔州地区晚第四系划分及古环境分析

大同盆地自形成以来,学者们对其西南部的朔州拗陷盆地的第四纪地层特征、气候及环境变化研究甚少。通过对大同盆地朔州市区实施的两个地质钻孔和收集的钻孔资料分析,结合22个土样的电子自旋共振及光释光测年结果,对研究区晚第四纪地层时代进行了划定,厘定了上、中、下更新统的地层界线。研究表明,区内上、中更新统以河流、洪积相沉积为主,下更新统以河流、湖相沉积为主;通过对12个样品的孢粉测试结果,揭示了研究区早更新世晚期以来的气候环境演变特征。在早更新世晚期和晚更新世晚期气候湿度相对较大,其余时期气候偏干,同时从早更新世晚期开始,朔州盆地内古湖泊开始收缩;最终建立了晚第四纪地层剖面,对本区地层划分具有重要的指导意义。     

西藏阿里札达盆地上新世-早更新世的古植被、古环境与古气候演化

本文将西藏札达盆地河湖相地层重新划分为第四系下更新统香孜组(Qp1-1x)、新近系上新统古格组(N22g)和上新统托林组(N21t)。河湖相地层的古地磁法和ESR法测年结果表明,札达盆地内河湖相沉积地层的形成时代为新近纪上新世—第四纪早更新世。根据该套河湖相地层沉积演化和其中的孢粉组合特征、河湖相沉积中所发现的各种古动植物化石等的综合分析,笔者对札达盆地上新世—早更新世的古植被、古环境与古气候演变进行了探讨。结果表明,札达地区上新世—早更新世气候经历了从湿热—温暖潮湿—偏冷潮湿—寒冷干旱的变化,以及植被从森林—灌木—草原的逐渐演化。可将札达盆地上新世—早更新世环境演化划分为7个大的阶段,其总体特征是15.4~4.4Ma,札达地区处于亚热带湿热气候环境;24.4~3.95Ma,为暖温带温暖潮湿气候;33.95~3.5Ma,为偏凉潮湿阶段,气候开始转冷;43.5~3.2Ma,为温暖潮湿阶段;53.2~2.9Ma,气候转为偏冷潮湿阶段;62.9~2.57Ma,该阶段气候偏冷而干旱,整体较为干冷;72.57~1.36Ma,气候寒冷而干旱。表明自上新世—早更新世,该区的古气候环境在逐渐变干、变冷的总趋势上,经历了多次明显的冷暖与干湿波动。     

大兴安岭北段东坡扎兰屯地区高位砂砾石层研究及其地质意义

通过对大兴安岭北段东坡扎兰屯东南前新生代基岩上高位砂砾石沉积的展布、沉积特征、砾组特征及孢粉分析等研究,分析本套砂砾石层的成因及其气候环境记录,并结合区域资料,探讨其形成时代和新构造意义.分析结果表明,研究区高位砂砾石层可划分为Ⅰ级、Ⅱ级和Ⅲ级高位砂砾石层,沉积时代初步厘定为早全新世、晚更新世和中更新世.3级高位砂砾石层均为河流作用的冲积成因,水动力条件较强,略具冲积扇特征,分别为雅鲁河Ⅰ级、Ⅱ级阶地沉积记录和嫩江Ⅲ级阶地沉积记录.孢粉分析显示,Ⅱ级和Ⅲ级高位砂砾石层沉积时为针叶森林草原环境,气候温凉干旱;Ⅰ级高位砂砾石层沉积时为落叶阔叶森林草原环境,气候温暖偏干,其后变为草原荒漠环境,气候寒冷干旱.雅鲁河主河道晚更新世以来由东向西略有迁移,嫩江主河道中更新世以来由西向东不断迁移,雅鲁河断裂和嫩江断裂所夹的断块中更新世以来存在3期抬升.     

雅鲁藏布江中游杰德秀古湖的发现及其意义

在雅鲁藏布江中游山南宽谷段发现了一套湖相沉积地层,形成时代为晚更新世晚期,为冰川阻江形成的堰塞湖沉积物。野外调查发现该套湖相地层在桑日县、乃东县、扎囊县等地均有出露,综合研究认为其为一个东起桑日县扎巴村、西至贡嘎机场附近的大型古堰塞湖泊,面积达700多km2。通过区域调查,该堰塞湖形成的湖相沉积地层在贡嘎县杰德秀镇出露最厚,厚10余m,主要由粉砂质黏土层、细砂层组成,水平纹层等湖相沉积特征明显,本研究称之为杰德秀古湖。杰德秀剖面顶部14C日历校正年龄为15 680～15 105 aBP,属于末次盛冰期。对比林芝古湖、格嘎古湖和松宗古湖等雅鲁藏布江下游堰塞湖的沉积物特征和形成时间,认为杰德秀古湖发育于末次盛冰期。沉积相特征和湖水库容量模拟分析表明,该堰塞湖发育时期,雅鲁藏布江中游山南宽谷段并未完全封闭,为一个湖水面积巨大的过水湖或吞吐湖,类似于现代过水水库。桑日县扎巴村雅鲁藏布江河谷两岸分布有冰碛物,其与雅鲁藏布江中游山南宽谷段的湖相沉积地层的时空关系指示杰德秀古湖与冰川阻塞河道有关,杰德秀古湖是由于冰川阻江形成的冰川堰塞湖。研究结果也进一步说明,雅鲁藏布江现代水系形成以前,其中游不存在面积巨大的众多古湖泊,雅鲁藏布江也不是溯源侵蚀疏干多个古湖泊而形成的,在古湖泊形成之前,雅鲁藏布江已经贯通。雅鲁藏布江流域内的古湖泊是由于气候变化、新构造运动或地震活动等原因造成河道堵塞形成的堰塞湖。     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。     

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.     

郯庐断裂南段研究进展与断裂性质讨论

据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。     

塘口水电站坝基岩体透水性和渗漏问题分析

塘口水电站大坝基础座落在断层和裂隙较发育的龟裂纹灰岩上,岩体完整性差、透水性强,多年运行后,大坝灌浆廊道和排水廊道出现多处集中性漏水,为确保大坝安全和电站正常发电,根据渗漏性质和成因,采用对灌浆廊道补充帷幕灌浆,对排水廊道进行固结+帷幕+回填灌浆。通过灌浆处理后,效果良好,表明灌浆工程有效的将导致坝基渗漏的上下游的裂隙通道封闭,并顺利的经受了随后的汛期洪水考验,大坝安全得到保障。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.     

Calculation of the Inverse of the Covariance

In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix.     

某高速公路下伏煤矿采空区稳定性分析

在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。      

Report of the restudy of the defined global stratotype of the base of the Silurian System

The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T ₃ = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.     

The Tendencies of the Development of the Mineral-Resources Sector at the Turn of the Century

Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base.