阿尔泰南缘吉木乃地区下二叠统沉积环境的地球化学判别

选用对沉积环境反映比较敏感的元素,对吉木乃地区珠万喀腊剖面早二叠世卡拉岗组14件泥岩样品开展主量元素、微量元素、稀土元素分析,分析研究区地层中微量元素含量及其比值与沉积介质环境之间的对应关系,进而探讨吉木乃地区早二叠世沉积期的湖盆气候条件、盐度、氧化还原条件等沉积环境特征。研究结果表明,古盐度指标w(B)、[m(Sr)/m(Ba)]和[m(B)/m(Ga)]平均值分别为51.32×10~(-6)、0.29%和2.42%,共同反映出吉木乃地区早二叠世为淡水环境,期间存在多个水体咸淡变化的次级旋回;氧化还原条件指标V/(V+Ni)、Th/U和U平均分别为0.82%、3.62%和0.92%,揭示出吉木乃地区下二叠统为缺氧环境下的沉积;经北美页岩标准化后发现泥岩中稀土元素比北美页岩的含量低,推测当时沉积应为化学风化作用较弱的较干燥气候,同时水体可能较安静。     

准南阜康地区中二叠统芦草沟组暗色泥岩地球化学特征及意义

准南阜康地区中二叠统芦草沟组暗色泥页岩厚度大、分布广,其沉积环境对评价页岩油气资源潜力具有重要意义。以芦草沟组暗色泥岩为研究对象,通过地球化学分析,选用对沉积环境指示较敏感的代表性元素,分析其含量特征及比值与沉积环境之间的对应关系,进而探讨芦草沟组沉积期湖盆的古盐度、古气候及氧化还原条件等沉积环境特征。通过Sr/Ba、B/Ga、B、Sr、Fe/Mn、Sr/Cu、U、Th/U和V/(V+Ni)等地化指标分析认为,阜康地区中二叠统芦草沟组暗色泥岩是高盐度、干热、缺氧环境下的产物。古盐度、古气候和氧化还原条件的变化趋势显示,准南阜康地区芦草沟组所代表的湖盆处于不断扩张的状态,具备良好的页岩油气资源潜力。     

松辽盆地西斜坡中—晚二叠世古沉积环境演化及油气地质意义

大兴安岭南部—松辽盆地西斜坡晚二叠世古沉积环境一直以来备受争议,关于该地区中—晚二叠世古环境演化方面的研究也鲜见报道。本文采用元素地球化学和有机地球化学相结合的研究方法,对松辽盆地西斜坡蒙科地1井中—晚二叠世古沉积环境演化特征进行综合研究。结果表明,中二叠世为明显的海相沉积,沉积水体相对较深,期间可能存在多次干热—暖湿波动,其中中二叠世ZSI晚期—ZSII早期较为明显,水体性质体现为咸水—微咸水—半咸水,水体还原性—偏氧化性—还原性,气候干热—温湿—干热。晚二叠世早期为微咸水—半咸水海相沉积,至晚二叠世晚期转变为淡水—微咸水海陆过渡相沉积,期间存在两次明显的气候环境波动,与中二叠世哲斯组沉积中期气候环境变化相似,表现为水体变浅、咸度降低、还原性减弱,气候由干热转向温湿。晚二叠世以来气候逐渐向温暖湿热转变,水体逐渐变浅,可能与二叠纪—三叠纪之交气候变暖有关。至三叠纪、侏罗纪时期,区域处于构造抬升阶段,沉积环境由海陆过渡相环境转变为陆相沉积。结合TOC、古生产力指标分析得出,中二叠世ZSI晚期—ZSII2早期、晚二叠世LXI晚期、晚二叠世LXII中期、晚二叠世LXIII沉积期偏湿润的气候条件和低咸度、弱还原—偏氧化性的沉积水体环境,是形成厚度较大、富有机质烃源岩的有利的气候环境条件。     

从地球生物学角度讨论华南中二叠世海相烃源岩缺氧沉积环境成因模式

探讨陆棚环境缺氧沉积的成因, 对查明海相优质烃源岩时空分布、恢复地史时期古环境演化具有重要意义.华南地区中二叠世栖霞组有机质丰富, 出现多方面缺氧沉积特征, 同时多门类底栖生物繁盛, 其成因一直令人困惑.简要介绍了陆棚浅海缺氧环境的生物特征及古氧相划分, 分析了栖霞组一个由纹层状灰岩和块状灰岩组成的典型的沉积序列的古氧相特征.块状灰岩的生物特征和地球化学特征均指示常氧沉积环境; 而纹层状灰岩的生物特征偏向常氧相, 沉积地球化学特征偏向厌氧相, 体现了陆棚缺氧沉积环境水体溶氧量不稳定的特点.栖霞组沉积特征表明, 栖霞组缺氧沉积环境的频繁出现与较高的生物产率有关.结合区域古地理和古特提斯古海洋背景, 认为华南地区中二叠世缺氧环境的成因与当时陆海分布格局和古海洋表面洋流系统有关.      

贵州烂泥沟金矿区中三叠统许满组、边阳组沉积地球化学及古环境特征

烂泥沟金矿位于南盘江坳陷,是我国一个超大型的卡林型金矿,地球物理和沉积相研究表明,该矿区整体位于斜坡相地层。本次研究以南盘江坳陷烂泥沟金矿中斜坡相地层中三叠统许满组、边阳组为研究对象,采用ICP-MS、ICP-AES等元素地球化学测试方法分析测试结果,明确其地球化学特征及沉积环境性质。研究结果表明：(1)许满组、边阳组暗色泥岩、粉砂质泥岩Cs元素强烈富集,Li, Cu, Sn, Pb, V,U等六元素相对富集,Ba元素亏损,泥岩总体富轻稀土;(2)该区中三叠世古水体较深,整体多为富氧—半咸水介质,仅许满组三段沉积期为咸水介质;(3)该区许满组三段沉积期为干旱气候,许满组四段沉积期为半潮湿-半干旱沉积环境;(4)该区中三叠世由大陆岛弧提供沉积物源。     

潜江凹陷古近系潜江组盐间泥岩地球化学特征及地质意义

咸化湖盆盐间泥岩的地球化学特征对咸化烃源岩的形成环境及其共生盐岩的形成条件具有重要指示意义。利用江汉盆地潜江凹陷内潜三下段盐间泥岩的详细地球化学测试结果,并结合岩芯观察,分析了古近系潜江组沉积时湖盆的古盐度、氧化还原环境及古气候背景。该地层较高的Sr丰度、Sr/Ba值及钙芒硝的存在揭示潜江组泥岩沉积时水体盐度较高;氧化还原环境指标及一些敏感元素的含量变化指示潜江组沉积时期水体含氧量较低,处于底层水体中等分层厌氧环境;主量元素化学蚀变指数CIA、Mg/Ca比值及对膏盐层岩芯观察反映潜三下段泥岩沉积于气候相对潮湿期段,而膏盐层则沉积于气候相对干旱期。这种泥岩与膏岩互层出现的变化可能是由我国晚始新世频繁的气候变化导致的。而且,由气候干湿波动造成的淡化-咸化成盐序列,伴随着生物短期的爆发与死亡,将有利于有机质的生成与堆积;潮湿、缺氧的沉积环境有利于有机质的保存,整体上盐间泥岩具备形成较好烃源岩的条件。     

微量元素分析在判别沉积介质环境中的应用——以鄂尔多斯盆地西部中区晚三叠世为例

以鄂尔多斯盆地西部中区晚三叠世样品中微量元素测试结果为基础,选用对沉积介质环境反映比较敏感的锶(Sr)、铜(Cu)、钡(Ba)、铀(U)、钛(Ti)、钒(V)、镍(Ni)等微量元素指标,分析研究区地层中微量元素含量及其比值与沉积介质环境之间的对应关系,进而探讨鄂尔多斯盆地西部中区晚三叠世的沉积介质环境。结果表明,鄂尔多斯盆地西部中区晚三叠世延长组长9-长7期基本为温湿气候且变得越来越温暖潮湿;长9-长7期为微咸水相的淡水环境,长7期盐度含量略有增加;长9、长8期水体的氧化还原条件比较正常,长7期变为厌氧环境;长9-长7期垂向上水体分层不强。     

内蒙古东部中二叠世吴家屯组海平面相对变化的泥岩地球化学证据

对内蒙古东部中二叠统吴家屯组泥岩进行了微量元素和有机地球化学研究,显示研究区吴家屯组水体的古盐度范围为16.6‰~28.7‰,主要为半咸水沉积。微量元素及其比值可以反映古盐度和古水深的变化,两者受海平面相对变化的影响;且古盐度、海平面相对升降在沉积相上有较好的响应。利用定量计算的古盐度和反映古盐度的Sr/ Ba、B/Ga值等编制了海平面相对变化曲线,显示研究区吴家屯组发生了2次海侵海退旋回,海侵发生在吴家屯组底部和中部。根据沉积相分析,结合地球化学指标V/(V+Ni)值、稀土元素Ce_anom及饱和烃气相色谱,表明区内吴家屯组主体为缺氧、还原的浅海陆棚环境,该环境有利于有机质的保存和烃源岩的发育。     

四川盆地西南缘下三叠统铜街子组-雷口坡组地球化学特征及其古环境意义

沉积岩的微量元素及稀土元素蕴含了大量的地质信息,是研究沉积物沉积时的古气候、古环境的有效手段。作者选取了四川盆地西南缘下三叠统铜街子组-雷口坡组的9件样品进行了主量元素、微量元素及稀土元素的测定。基于能够敏感反应沉积环境的微量元素指标及特征微量元素、稀土元素比值,对四川盆地西南缘早三叠世铜街子组-雷口坡组沉积时期的古环境、古气候进行了研究。结果表明:四川盆地西南缘下三叠统铜街子组-雷口坡组的岩石具有富TiO_2、MgO、CaO、K_2O等,贫SiO_2、Na_2O的特点。相对于地壳,稀土元素总量较高,具中等的负铕异常,w(LREE)/w(HREE)比值较高。四川盆地西南缘下三叠统铜街子组-雷口坡组的沉积环境演化分为9个时期:自下而上,干热(氧化,水体分层弱)→温湿(氧化,水体分层弱)→冷湿(缺氧、水体分层性极弱)→干热(氧化,水体分层弱)→温湿(缺氧,水体分层强)→干热(氧化,水体分层弱)→温湿(氧化,水体分层弱)→温湿(氧化,水体分层性强)→干热(氧化、水体分层性中等-强)。为该区早三叠世环境演化研究提供基础资料。     

川南地区二叠系沉积环境及其演化特征——以四川古蔺芭蕉村剖面为例

以四川古蔺芭蕉村二叠系剖面为研究对象,在野外沉积特征详细观测的基础上,利用岩石薄片鉴定、全岩X衍射分析、元素地球化学与碳、氧、锶同位素分析,对其地层、沉积环境与演化特征进行研究,为四川盆地二叠系沉积特征研究与天然气勘探提供基础资料。研究表明,四川古蔺芭蕉村地区从中二叠世的梁山—栖霞组沉积时期开始海侵,栖霞组由下向上水体先变深又变浅,呈缺氧—贫氧环境;茅口组底部又一次海侵,以继承栖霞组沉积环境为特征,在茅口组一段水体最深,向上逐渐变浅,呈缺氧—贫氧特征;龙潭组沉积水体最浅,氧化环境为主,局部呈还原环境;长兴组底部沉积水体最深,整体呈缺氧—贫氧特征,其碳酸盐岩沉积的海平面相对中二叠统应较浅。宏观上,四川盆地中二叠统栖霞组、茅口组由东向西为碳酸盐岩缓坡逐渐向台地演化。茅口组三段发育大型的溶蚀孔洞和后期溶蚀缝洞,推测该区茅口组有可能形成岩溶缝洞型储层。长兴组的底部发育水体较深的台盆次相沉积,环台洼或台盆可能是礁滩发育的有利区。见大量的沥青质充填,考虑到川南地区二叠系发育富有机质的碳酸盐岩与黑色页岩及煤层,认为该区二叠系具备形成古油藏的可能。     

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″.     

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.     

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。     

On the consistency of proposed models for the Pyrenees with the structure of the eastern parts of the belt

The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time.     

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.