末次盛冰期和全新世大暖期呼伦贝尔沙地的环境变化

呼伦贝尔沙地保存的风沙层-古土壤沉积序列,是认识过去环境变化的重要地质记录.沙地沉积具有速率快、沉积与侵蚀并存的特点,因此,通过大量独立的光释光年代控制对不同的剖面进行拼接,可以重建沙地在千年尺度上干湿变化过程以及特征时期的边界.本文获得了呼伦贝尔沙地8个沉积剖面的47个光释光年代和近200个样品的环境代用指标数据,结合已发表文献资料,揭示了16ka以来呼伦贝尔沙地千年尺度的干湿变化,并估算了末次盛冰期(LGM)和全新世大暖期(HO)沙地流沙的边界.初步认为,LGM期间,呼伦贝尔沙地相对于现代沙带边界,最远向北移动了约60km,向东移动了约50km,并且南北沙带之间的区域全部沙化;LGM期间沙漠化面积达到22337km2,相对现代沙漠化面积扩大了约2.7倍.而在HO期间,整个沙地被植被所固定,发育砂质古土壤层,只在局部区域存在短暂的风沙活动.     

末次盛冰期和全新世大暖期毛乌素沙地的空间变化

沙漠/沙地边缘和内部的古风成沙层、砂质古土壤是重建晚第四纪以来地表变化的直接地质证据.位于我国北方半干旱区的毛乌素沙地,其地表过程对气候变化响应敏感.在对毛乌素沙地进行野外拉网式调查以及前人研究的基础上,我们在沙地南部和东部的沙漠-黄土过渡带发现了大量的埋藏古风成沙丘沉积,指示了干冷期沙漠扩张的最南、东界限;沙地内部广泛发育的砂质古土壤则表明在气候相对暖湿期地表植被生长,土壤发育,沙丘基本被固定.对14个典型风成沙/黄土/古土壤沉积剖面进行了光释光年代学样品的采集和测试,结合空间分析和他人研究结果,发现在末次盛冰期(约26 ～ 16ka),毛乌素沙地的流动沙丘向南、东扩张,扩张距离现代边界约30～ 50km,面积扩大至少约10000km2,占现代沙地面积的25％;在全新世大暖期(约9～5ka),毛乌素沙地大部分被固定,发育了较厚的砂质古土壤.研究结果揭示了毛乌素沙地的地表过程对末次盛冰期和全新世大暖期气候变化的直接响应.     

末次间冰期以来沙漠-黄土边界带移动与气候变化

位于现代季风区边缘的沙漠－黄土边界带，具有高度不稳定性。末次间冰期以来历经多次北进南退移动和暖湿、冷干变化。依据古风成砂－黄土－古土壤叠覆更替的沉积序列和磁化率等气候代用指标分析，对末次间冰期以来，尤其是特征时期边界带的位置进行了讨论。其中，盛冰期时移动幅度最大，南界可能达３０°Ｎ左右；末次间冰期和全新世气候鼎盛期最靠西北，南界在古长城以北。全球冰期－间冰期波动导致的气候变化以及东亚冬夏季风强弱变化是控制边界带移动和气候变化的根本因素。     

光释光测年揭示的科尔沁沙地末次晚冰期-全新世沙漠空间格局变化

对中国东北地区科尔沁沙地13个风成沙剖面和3个黄土剖面进行了研究,测试分析了黑色砂质土壤和下伏古风成沙的OSL年龄及粒度、磁化率、色度数据;OSL测年获得的古风成沙数据位于末次冰期晚期-全新世期间(13 ～1Oka),小于26.5 ～19.Oka的末次冰盛期时段.末次冰盛期干冷气候背景下沙丘持续不断的活化翻动,风成沙在进入全新世气候转暖后才被固定,沙地内全新世黑色砂质土壤下伏的疏松流沙为末次冰盛期产物,其分布范围可代表末次冰盛期流动沙丘的分布范围.现今科尔沁沙地面积约为42000km2,活动沙丘面积约占10％.在末次冰盛期不仅原固定沙丘活化,沙质平原与部分甸子也被流沙覆盖,面积约85000km2,活动沙丘或流沙面积相对目前扩大了约20倍.末次冰盛期沙地活化扩张的控制因素主要有两方面:一方面冰期气候干旱寒冷,降水减少,地表植被覆盖下降,地表松散沉积物遭受风力剥蚀而活化成流沙;另一方面科尔沁沙地内部水系发育,河流流经途中会沉积大量松散物质.在冰期干冷环境下,河流水位下降,河流沙暴露并遭受风蚀改造,为流沙扩张提供物源,沙漠沿西拉木伦河流域扩展.     

五十万年来毛乌素沙漠的变迁

对沙漠-黄土边界带的古风成砂-黄土-古土壤序列的研究表明，毛乌素沙漠至少在0.5MaB.P.就已出现，但也并非从其出现之初就持续至今。沙漠-黄土边界带的风成沉积所记录的沙丘活化和固定的多次转变是第四纪时期毛乌素沙漠对气候振荡响应的结果。五十万年来，沙漠-黄土边界带的石峁剖面记录了13层古风成砂，代表了13次沙漠大规模的南侵。沙漠的南侵不仅可以发生在冰期鼎盛之时，同样也可以发生在间冰期中的寒冷气候幕出现之时。此外，鉴于沙漠-黄土边界带具有气候敏感性的特点，石峁剖面的地层记录还表明了第四纪时期不仅有冷期与暖期的多次旋回，而且冷期和暖期发生时还有次一级的气候波动。     

近13万年来黄土高原干湿气候的时空变迁

第四纪时期，黄土高原粉尘物质的搬运、沉积及其后的成土过程受控于干湿气候的变化。对黄土高原这一特定地区而言，风成沉积序列在地域上的差异主要与东亚地区的季风环流在时间和空间上的变化有关。本文的研究揭示出，近１３万年里，最为显著的成壤期有６期，与这６个成壤期对应的时段也应当是夏季风环流加强、气候温湿的时期；在空间上，全新世适宜期及末次间冰期中与深海氧同位素阶段５ａ，５ｃ，５ｅ对应的时期，夏季风足可以深入到毛乌素沙漠腹地，并具有占优势的环境效应。在阶段３的早、晚期及５ｂ时期夏季风虽然也能深入沙漠－黄土边界带，但其环境效应在黄土高原北部及毛乌素沙漠南缘已不再显著。在阶段２、阶段４及阶段３的中期夏季风已不能深入沙漠－黄土边界带。     

末次间冰期以来沙漠－黄土边界带的环境演变

沙漠－黄土边界带地处东亚季风边缘，这一地区的风成沉积即古风成砂－黄土－古土壤序列很好地反映了东亚季风环流的演变历史。末次间冰期的沉积(Ｓ１)由三层古土壤和夹于其间的两层黄土组成，可与深海氧同位素阶段５的五个亚阶段(ａ－ｅ)则很好对比。末次冰期的沉积(Ｌ１)由三层古风成砂和夹于其间的两层黄土构成，由此反映了与上述三层古风成砂对应的阶段２、阶段４及阶段３的中期是沙漠－黄土边界带冬季风活动加剧、沙漠扩大的时期。全新世的沉积是由一层草原上(Ｓ０)和其上的流沙组成，但这层流沙是在最近两千年来不合理的人类活动和当地特定风场条件的共同作用下形成，已不具备明显的气候指示意义。     

末次间冰期以来沙漠－黄土边界带的环境演变

沙漠－黄土边界带地处东亚季风边缘，这一地区的风成沉积即古风成砂－黄土－古土壤序列很好地反映了东亚季风环流的演变历史。末次间冰期的沉积（Ｓ１）由三层古土壤和夹于其间的两层黄土组成，可与深海氧同位素阶段５的五个亚阶段（ａ－ｅ）则很好对比。末次冰期的沉积（Ｌ１）由三层古风成砂和夹于其间的两层黄土构成，由此反映了与上述三层古风成砂对应的阶段２、阶段４及阶段３的中期是沙漠－黄土边界带冬季风活动加剧、沙漠扩大的时期。全新世的沉积是由一层草原上（Ｓ０）和其上的流沙组成，但这层流沙是在最近两千年来不合理的人类活动和当地特定风场条件的共同作用下形成，已不具备明显的气候指示意义。     

甘孜绒坝岔古冰川演化与黄土古土壤对比研究

横断山脉绒坝岔，保留有从倒数第二次冰期到新冰期的较完整的冰川沉积序列。对冰碛物进行了ESR测年，其分别形成于5．6kaBP、新冰期与末次冰期之间、16．3kaBP、18．7kaBP、43．7kaBP以及倒数第二次冰期。TL测年结果显示，甘孜雅砻江江畔阶地黄土从末次冰期之初开始堆积，结合甘孜黄土-古土壤序列代用指标的综合分析，发现绒坝岔冰碛物形成年代与甘孜剖面黄土、古土壤沉积年代有较好的对应关系。末次冰盛期(LGM)，绒坝岔冰碛垄走向有一次接近90。的改变；末次冰期间冰段，对应于MIS3b，其冰川规模甚至超过了LGM时期。     

浑善达克沙地沙丘剖面颜色变化的古气候意义

为研究中国沙漠东部广泛分布的风成沙-古土壤沉积序列的颜色变化与古气候之间的可能联系,以浑善达克沙地为研究区,测定了7个天然风成沙-古土壤沉积序列的颜色(L*a* b*)、有机碳、总氮和粒度。结果表明:L*(亮度)、a*(红度)、b*(黄度)值分别介于32.41~65.89,2.73~7.52和-1.68~17.16;L*、a*、b*值之间存在正相关关系,其中L*和b*之间的相关性最显著(R2=0.90),而L*和a*之间的相关性最低(R2=0.26);L*、a*、b*值在垂直方向上具有相同的变化趋势和特征,它们在风成沙层位处为高值,在灰色-黑色砂质古土壤层位处为低值,但L*值变化较大,a*和b*值变化较小。均值的非参数检验表明L*可指示风成沙-古土壤沉积序列的风成沙和古土壤层的变化,而a*在这类沉积序列上变化不敏感。影响L*的主要因素与有机质含量和成壤作用有关,它们都与东亚夏季风强弱变化关系密切,因此L*有明确的古气候意义;L*低值对有机质含量增加和成壤作用的加强具有指示作用,是东亚夏季风增强的信号。基于颜色参数L*可以很好地重建中国沙漠东部风成沙-古土壤沉积序列的古气候变化。     

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.     

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″.     

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 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.     

Causes of the famine among the rural population of the Sahelian zone of the Sudan

Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators.     

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。     

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.