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1.
吉南地区的寒武纪生物化石(以三叶虫为主)极其发育,前人曾对其进行了详尽的研究,先后建立了7个阶17个化石带。但化石带的含义不甚明确,多以标准分子为代表,即标准化石带(时间带?)。笔者等于1991 ̄1993年在白山市幅(1/5万)区调填图时,以区内的青沟子剖面为例,利用前人在该剖面上连续采集的三叶虫生物化石资料,按照多重地层划分的原则,对生物地层单位进行了初步清理,建立了5个正式生物地层单位-延限带  相似文献   

2.
元江地区三叠系地层特征及其归属   总被引:1,自引:0,他引:1  
曹德斌 《云南地质》2001,20(4):392-400
从岩性,化石,生物地层,沉积环境等方面对元江地区三叠系地层特征进行讨论。通过与邻区对比,元江地区的上三叠统应划属滇东南地层区,与火把冲组相比。根据所获化石建立Burmesia-Costtoria-Indosinion组合带,归属诺利-瑞替阶,对研究云南三叠纪地史,恢复古地理,古地貌具有重要意义。  相似文献   

3.
南海北部深水区LS33a钻井微体古生物年代地层格架   总被引:1,自引:0,他引:1  
南海北部琼东南盆地深水区接收了渐新世以来数千米厚的海相沉积地层,蕴藏着丰富的微体古生物化石。对深水区LS33a钻井岩芯的取样和化石鉴定,识别出21个浮游有孔虫化石带(N22带~P19带)和12个钙质超微化石带(NN19带~NP24带)。通过与大洋钻探(ODP)在南海实施的184航次的钻探结果和“国际年代地层表(2012)”等的对比分析,探讨了化石事件的地质年代意义,构建了LS33a钻井生物年代地层格架。在此基础上,讨论了更新统与上新统、上上新统与下上新统、上新统与中新统、上中新统与中中新统、中中新统与下中新统、中新统与渐新统、上渐新统与下渐新统之间地层界线位置以及崖城组、陵水组、三亚组、梅山组、黄流组、莺歌海组和乐东组地层的时代归属,建立了适用于南海北部深水区的高分辨率综合年代地层格架。  相似文献   

4.
西藏南部珠穆朗玛峰地区三叠纪生物地层研究   总被引:5,自引:0,他引:5  
本文对珠穆朗玛峰地区三叠系地层中的生物地层层序、古生物化石的产出状态、组合面貌和发育特征等进行了详细的研究,自下而上将区内三叠系划分出19个生物化石组合(带)。这些生物化石组合(带)分别是:①Oceras latilobatum-Anchignathodotus parvus组合;②Ophiceras sakuntala-lsarcicella isarcica组合;③Gyronites psilogyrus-Claraia aurita-Neospathodus cristagalli组合;④Owenites-Neospathodus waageni组合;⑤Procarnites xizangensis-Neogondolella milleri组合;⑥Neospathodus timorensis带;⑦Japonites mangus-Neogondolella regale组合;⑧Anacrochordiceras nodosus-Tulongospirifers tracheyi组合;⑨Paracertites trinodosus-Neogondolella constricata组合;⑩Protrachyceras ladinum-Daonella indica-Neogondolella excelsa组合;⑾Indonesites dieneri-Lilaggina nobilis组合;⑿Haplotropites-Epigondolella diebeli组合;⒀Parahauerites acutus-Halobia-Neogondolella polygnathiformis组合;⒁Nodotibetites nodosus-Epigondolella abneptis组合;⒂Griesbachites-Guembilites组合;⒃Indojiuwavites angulatus-Epigondolella multidentata-Himalayasaurs tibetensis组合⒄Cyrtopleurites bicrenatus带;⒅Pinacoceras metternichi-Himavatites columbianus组合;⒆Tulongocardium pluriraditum-Palaeocardita mansuyi组合。据此厘定了该区三叠系下统、中统和上统的界线。珠穆朗玛峰地区三叠系生物化石组合带的重新建立,提高了该区三叠系生物地层的研究程度,为开展青藏高原地区及其与全球的三叠系地层划分对比研究提供了科学依据。  相似文献   

5.
河北怀来-涿鹿盆地更新统自下而上划分为泥河湾组、官厅组、马兰组和吉家营组个组,其中吉家营组为一新建立的岩石地层单位。通过详细的生物地层学研究,共划分出3个介形虫化石组合带、3个瓣鳃类及腹足类化石组合带和8个孢粉组合带,结合各组同位素年龄数据,对其形成时代进行了探讨。  相似文献   

6.
浙江省老虎洞组和黄龙组地层划分与对比   总被引:1,自引:0,他引:1       下载免费PDF全文
浙江省老虎洞组、黄龙组生物地层的研究较薄弱,尤其是笾化石带的建立不够系统,使地层的正确划分和对比存在一些问题。笔者通过精测浙江省桐庐县杨家老虎洞组、黄龙组地层剖面,系统采集了筵化石样品,经筵薄片研究。自下而上新建2个筵化石带:Profusulinella simplex带和FusulineUa bocki—Fusulina mayiensis带(二带化石归属达拉阶)。并与浙江长兴、杭州、常山地区的老虎洞组、黄龙组剖面进行了生物地层和岩石地层的划分对比。对比结果表明:Profusulinella simplex带上延至黄龙组中一下部,  相似文献   

7.
新疆觉洛塔格地层分区东部石炭系   总被引:2,自引:0,他引:2  
觉洛塔格地层分区广泛发育早石炭世及晚石炭世早期的火山-沉积建造。以雅满苏大断裂为界,分为南部的雅满苏地层小区和北部的苦水地层小区,为两个不同的沉积构造环境:南部为岛弧火山岩沉积相区;北部为弧间盆地沉积相区。雅满苏小区划分出小热泉子组、雅满苏组、白鱼山组和底坎尔组4个岩石地层单位。苦水小区划分出雅北组、梧桐窝子组、干墩组、白鱼山组和苦水组5个岩石地层单位。分别叙述了两个地层小区岩石地层单位的分布、剖面层序及确定地层时代的化石依据。  相似文献   

8.
黔南斜坡相区二叠系层序地层序列及其年代地层对比   总被引:30,自引:4,他引:26  
黔南斜坡相区的二叠系划分为16个三级层序,4个层序组,分属于2个中层序。大多数三级层序的底界属整合界面,有良好的牙形石和化石带控制。该区二叠纪有4次重要的海平面下降事件,它们分别出现在牙形石Swwhitei带底部,Swafhanzhongensis带下部,JXuanhanensis带下部以及Clyini带底部。已识别的海进事件中,有3个最具地层划分和对比意义,分别出现在牙形石Nexculptus带底部,Jnankingensis带底部和Jpostbiteri带下部,均伴随有重要的生物群替代。研究表明,沉积层序的关键界面对于进一步优化阶和生物时带的界线,使年代地层界线成为野外可识别的物理界面具有重要的潜在价值。  相似文献   

9.
在原划若拉岗日群分布区内新发现混杂有二叠纪外来岩块,在构造透镜体灰岩中见有晚二叠世长兴期有孔虫化石.在晚三叠世苟鲁山克错组中采集到丰富的植物化石,其中以种子蕨纲的属种Hyrcanopteris最多,与唐古拉山结扎群、土门格拉群及藏东甲丕拉组、巴贡组以蕨类Neocalamites,Equisetites为主的晚三叠世植物群有所差异.侏罗系是调查区内分布面积最大、地层系统发育最完整的岩石地层单元,建立了2个生物组合、3个生物组合带、3个组合亚带.建立了一条高精度古地磁控制的地层剖面,为第三系陆相红层沉积时代的确定和对比提供了依据.据新的同位素测年数据和分析结果,确认藏北面积最大的新生代火山熔岩的形成时代为45~40Ma,它源于EMⅡ型富集地慢.发现乌兰乌拉湖构造混杂岩带,为区域构造对比提供了新的依据.  相似文献   

10.
甘肃的侏罗系   总被引:4,自引:0,他引:4  
以岩石地层学观点对甘肃的侏罗系进行了划分和对比。共划分出北祁连等7个地层区,23个组级岩石地层单位;列述了各组的层型和次层型、各组的定义和研究史及沿革情况,提出停用的地层单位和停用原因。按植物化石成分将西秦岭地区划为Coniopteris-Phoenicopsis植物群与Coniopteris-Ptelophylum植物群的混生区,其北为Coniopteris-Phoenicopsis植物群区系。分析了侏罗纪岩相、古地理概况,按世恢复其古地理面貌。列述各组生物化石,讨论各组的地质时代。简述侏罗系中沉积矿产的形成规律和规模。根据构造体系复合情况及地层分布,预测省内4个地区6个盆地和低地为形成煤和石油的有利地段。  相似文献   

11.
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.  相似文献   

12.
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″.  相似文献   

13.
14.
Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated.  相似文献   

15.
16.
摩擦桩基桩土间极限摩阻力取值问题探讨   总被引:1,自引:0,他引:1  
陈银生 《世界地质》1999,18(1):54-59
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。  相似文献   

17.
从榴辉岩与围岩的关系论苏鲁榴辉岩的形成与折返   总被引:4,自引:1,他引:4       下载免费PDF全文
位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压,而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩,榴辉岩及其他直接围岩皆呈包体存在于其中,并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体,表明新元古代花岗岩的组成物质也经受过超高压变质作用,且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次(或阶段)却少于榴辉岩。椐上述可得如下推断:超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部(俯冲板块前部)形成的;榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的,其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升,遭受剥蚀。  相似文献   

18.
某高速公路下伏煤矿采空区稳定性分析   总被引:10,自引:0,他引:10  
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。   相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

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