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1.
塔里木板块上元古界火山岩SHRIMP定年及其对新元古代冰期时代的制约 总被引：16，自引：7，他引：9
新疆库鲁克塔格地区贝义西组顶部火山岩锆石的SHRIMP定年结果为732±7Ma,它表明贝义西冰期的上限。考虑该组杂砾岩之下火山岩已有的定年结果,贝义西冰期的时限为740~732Ma。综合上元古界三层火山岩SHRIMP定年结果,可以明确地将库鲁克塔格地区上元古界四个含杂砾岩的组限定在三个时间段内,即740Ma到732Ma的贝义西组,732Ma到615Ma之间的阿勒通沟组和特瑞爱肯组,以及615Ma到542Ma之间的汉格尔乔克组,这些年龄段代表了库鲁克塔格地区新元古代各冰期的时代范围。与冰期有关的同位素年代学资料分析表明,贝义西冰期可与Kaigas冰期对比; 阿勒通沟冰期和特瑞爱肯冰期可能与Sturtian冰期和Elatina冰期对比; 而汉格尔乔克冰期和Gaskiers冰期可以对比。 相似文献
2.
新元古代冰碛岩地层记录了“雪球地球”极端气候事件重要的地质信息。塔里木地块东北缘库鲁克塔格地区、西北缘阿克苏地区和西南缘叶城地区新元古代冰碛岩地层露头发育,是研究新元古代冰期事件的理想基地。文章基于塔里木地块周缘新元古界详实的野外地质调查工作,综合了地层学、同位素年代学、岩石地球化学等研究,聚焦冰碛岩地层沉积时代这一核心问题,建立新元古代冰期格架。冰期事件对比显示,贝义西冰期(库鲁克塔格地区)相当于Kaigas冰期(国际),阿勒通沟冰期(库鲁克塔格地区)、巧恩布拉克冰期(阿克苏地区)、波龙冰期(叶城地区)相当于Sturtian冰期(国际),特瑞爱肯冰期(库鲁克塔格地区)、尤尔美那克冰期(阿克苏地区)、雨塘冰期(叶城地区)相当于Marinoan冰期(国际),汉格尔乔克冰期(库鲁克塔格地区)相当于Gaskiers冰期(国际)。同时基于冰期事件对比关系,建议根据国际地层委员会的最新划分方案将塔里木地块南华系底界调整为与全球性Sturtian冰期沉积底界相当的层位。通过探讨新元古代冰期事件与古老烃源岩发育的耦合关系,分析了新元古界优质烃源岩的发育潜力,指出塔里木地块新元古界具备良好的油气成藏地... 相似文献
3.
采自欧龙布鲁克地块全吉山、欧龙布鲁克山两个剖面全吉群下部砂砾岩段(包括麻黄沟组与枯柏木组)样品ICV指数大多数1、或略1,这表明该套碎屑岩沉积是构造活动地带的初始沉积。底部冰成岩发育层段样品CIA指数大多数在53左右,向上CIA指数增大至67左右,反映新元古代早期研究区古气候整体转暖。底部层段样品极低的CIA值表明欧龙布鲁克板块新元古代早期主要发生寒冷气候条件下的低等程度化学风化,首次从CIA指数角度证实研究区存在新元古代早期极端寒冷气候事件,为研究区受新元古代早期"雪球地球"事件影响提供了更进一步的证据。通过对前人年代学研究的总结,将这套含有大量低CIA值碎屑岩的冰川沉积地层沉积年限约束在780±20~740±16Ma范围内,并认为其与国际上的Kaigas冰期及塔里木地区贝义西冰期相对应。 相似文献
4.
塔里木板块上元古界阿勒通沟组和黄羊沟组: 新识别的冰期和间冰期？ 总被引：3，自引：2，他引：1
通过库鲁克塔格地区孜厄肯—厄格孜达坂一带实测地层剖面研究重新建立了阿勒通沟组和黄羊沟组的地层层序。阿勒通沟组含三层冰成杂砾岩,为冰川沉积与滨-浅海沉积交替发育,代表海相环境下的冰川沉积。黄羊沟组底部白云岩具负的δ13C同位素值,下部以火山岩、上部以细碎屑岩和碳酸盐岩为主,沉积环境具有向上变深的特征,代表了阿勒通沟冰期结束后温暖环境下的海平面上升。结合冰成杂砾岩的特征、“盖帽碳酸盐岩”的分布、碳同位素和化学蚀变指数方面的证据,可将两者分别确定为独立的冰期和间冰期,并分别沿用阿勒通沟冰期和黄羊沟间冰期的称呼。阿勒通沟冰期的划分使得库鲁克塔格地区晚元古代冰期达到四次。根据库鲁克塔格地区已有的同位素年龄,阿勒通沟冰期可能与Sturtian冰期对比,贝义西冰期可能与Kaigas冰期而不是与Sturtian冰期对比。 相似文献
5.
新疆的南华系及我国南华系的几个地质问题--纪念恩师王曰伦先生诞辰一百周年 总被引：25，自引：0，他引：25
新疆的南华系广泛发育在库鲁克塔格、柯坪、西天山及塔里木西南部地区，以库鲁克塔格地区层序最为完整。本文作者对该区晚元古界的冰期划分提出了新的认识，认为该区新元古界共有四次冰川活动(共可划分为4个冰期和3个间冰期)。其中南华系有三次冰川活动(三个冰期和两个间冰期)的沉积，自下而上为贝义西冰期(第一冰期)、照壁山间冰期(第一间冰期)、阿勒逼沟冰期(第二冰期)、“黄羊沟间冰期(第二间冰期)”和特瑞爱肯冰期(第三冰期)；另外属于震旦纪的还有，扎摩克提组、育肯沟组、水泉组(第三间冰期)，汉格尔乔克冰期(第四冰期)。作者认为我国南华系的时限应大体为680～850Ma。在我国北方乔有南华纪的地层存在，如辽东的桥头组、长岭子组、营城子组等及山东东部的辅子夼组、马山组等，但迄今尚未发现有可靠的冰成岩的报道。华北地区的罗圈组、正目观组、红铁沟组曲冰碛层均属于震旦纪末罗圈冰期的冰川活动，与汉格尔乔克冰期相当，并不相当于华南南华纪晚期的南沱冰期。 相似文献
6.
关于塔里木北缘南华-震旦纪的构造演化存在争议,本文研究了其东北缘库鲁克塔格地区南华系阿勒通沟组的沉积环境、地球化学特征等方面,揭示其源区风化、物源类型和构造背景等信息,以期为塔北同期构造演化及古地理环境恢复提供更多证据。阿勒通沟组由底部的冰碛砾岩和之上发育细密纹层的细砂-粉砂-泥岩组成,砂岩中发育丘状交错层理、渠模等典型风暴沉积构造,可识别出3种风暴沉积序列,为风暴浪控浅海陆棚沉积,是阿勒通沟组冰期和特瑞艾肯组冰期分属两个冰期的有力证据。该组宽广陆棚相的沉积环境,砂岩较高的结构成熟度及V-Cr-Ni-Sc负异常、Ti-Hf-Zr-Y正异常等地球化学特征皆显示其处于被动大陆边缘。物源判别图解、过渡族元素含量和稀土配分特征显示该组砂岩主要碎屑物质为来自南部塔里木克拉通的长英质岩类,另有古老沉积岩的加入。砂岩样品CIA值、A-CN-K图解和Th／U比值等显示其源区经历了微弱-中等的化学风化,碎屑物质具沉积分选、沉积物再旋回特征,且在成岩过程中钾交代明显,这些特征也与被动大陆边缘一致。在此基础上,结合前人研究成果认为库鲁克塔格自贝义西组裂解至阿勒通沟组演化为被动大陆边缘,且至少持续到震旦系扎摩克提组。 相似文献
7.
库鲁克塔格地区新元古代沉积物源分析:来自碎屑锆石年代学的证据 总被引：6，自引：2，他引：4
库鲁克塔格位于南天山和塔里木盆地接合部,保留相对较完整的地层记录。新元古代贝义西组主要为一套火山-沉积组合序列,育肯沟组为浊流成因的砂岩和粉砂岩组合。对取自两个地层的沉积岩样品,分别进行了碎屑锆石LA-ICP-MS U-Pb测年,并分别获得了93组和71组U-Pb有效年龄。其中贝义西组锆石U-Pb年龄主峰值为821Ma、次峰值为861Ma的碎屑锆石(761~847Ma)具有显著优势,育肯沟组年龄值为768Ma(次峰值为800Ma和741Ma)的碎屑锆石比较集中,说明库鲁克塔格地区在741Ma、768Ma、800Ma、821Ma和861Ma有大规模的岩浆活动。10个太古代碎屑锆石年龄以及综合已有的研究成果,确认库鲁克塔格存在中-新太古代基底。贝义西组砂岩主要源自761~847Ma、851~972Ma和1808~2498Ma岩石。育肯沟组主要来自734~845Ma、858~963Ma和1708~2486Ma的岩石。 相似文献
8.
中国塔里木板块南华纪成冰事件及其地层对比 总被引：4，自引：0，他引：4
"雪球地球"假说为全球新元古代冰碛岩研究注入了新的活力。各国地质学家根据新元古代冰碛岩全球各大洲发育的特点,并依据同位素年龄、δ13C/δ18O和Sr的比值和化学蚀变指数(CIA)为全球的新元古界划分出4个冰期,但国际上的4个冰期的限定,是各大洲不同剖面冰期的集合。新元古代冰期事件周期变化视为早期生物复苏和早期动物分异的起点。由于国际埃迪卡拉系底界(GSSP)年龄,即成冰系顶界年龄确定后,使成冰系底界年龄成为当前研究的重点。中国新疆塔里木板块库鲁克塔格地区新元古代冰碛岩是目前世界各大陆中发育有4套连续的新元古代冰碛岩和多期火成岩事件的唯一剖面,它的进一步深入研究,可以备考全球冰期的同步性,以期建立全球新元古代冰碛岩标准剖面。本文报道了来自塔里木西南缘南华系波龙组的碎屑锆石年龄,有助于我们对塔里木板块西南缘南华系时代的限定。 相似文献
9.
新疆南雅尔当山震旦系的新观察 总被引：1，自引：0，他引：1
新疆南雅尔当山震旦系出露层序完整,它与下伏前震旦系呈不整合接触,与上复寒武系为假整合,总厚2017m。根据岩性自上而下划分为汉格尔乔克组、水泉组,育肯沟组、特瑞爱肯组、黄羊沟组、阿勒通沟组和贝义西组,其中贝义西组为火山岩,获同位素年龄为814±97Ma,阿勒通沟组和汉格尔乔克组为冰碛层。 相似文献
10.
新元古代是冰川作用发育的重要时期,其中有2个重要的全球性冰期,即Sturtian和Marinoan冰期,对全球古环境、古气候、古海洋演化具有重要意义。中国宜昌地区分布的莲沱组和南沱组分别代表了在扬子板块发育的与Sturtian冰期前和Marinoan冰期相对应的沉积地层。随着地球化学分析方法的进步,新的地球化学手段,包括新的地球化学指标和Fe同位素等,可以为进一步探讨莲沱组与南沱组的沉积环境提供新的思路和证据。本研究对宜昌九龙湾剖面南沱组冰碛岩进行系统采样,并和莲沱组以砂岩为主的碎屑沉积岩进行对比分析,利用化学蚀变指数(CIA)、氧化还原敏感元素Mo、V、U和Fe同位素对比探讨二者古气候与氧化还原环境的演化。CIA的变化(53～78)表明,莲沱组沉积主体处于温暖的古气候下(CIA平均值约为78),直到Sturtian冰期前,莲沱组顶部出现气候转冷特征(CIA平均值为53);随着Marinoan冰期到来,南沱组沉积持续处于寒冷的古气候环境(CIA平均值为58)。莲沱组与南沱组样品均具有较低的Mo/Al、V/Al和U/Al值,表明二者沉积均处于氧化环境,但莲沱组主体比南沱组和莲沱组顶部样品... 相似文献
11.
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。 相似文献
12.
The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
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
13.
Guboglo M. N. 《GeoJournal》1980,4(1):53-58
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
14.
15.
郯庐断裂南段研究进展与断裂性质讨论 总被引：13，自引：3，他引：13
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。 相似文献
16.
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
17.
Jiayu Rong Michael Melchin S. Henry Williams Tatyana N. Koren Jacques Verniers 《《幕》》2008,31(3):315-318
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. 相似文献
18.
Dean S. Oliver 《Mathematical Geology》1998,30(7):911-933
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. 相似文献
19.
Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
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
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正Artemia cysts are an extremely important component of aquaculture diets.It is well established that the cultivation of fish and shellfish derive substantial health and growth advantages when Artemia are included in the diets of the 相似文献