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1.
青藏高原古大湖与夷平面的关系及高原面形成演化过程 总被引：4，自引：2，他引：2
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。 相似文献
2.
通过对中新统五道梁群湖相沉积进行全岩心钻探和碳氧同位素测试,获得青藏高原北部中新世早期古环境变化和古气候旋回的重要地质记录.五道梁群约150 m湖相沉积以灰岩、白云质灰岩与泥灰岩为主.仅在深度50.0～51.0 m出现湖相沉积间断,上下均为连续湖相沉积.深度140～145 m湖相沉积碳氧同位素剧烈变化,碳同位素(δ13C/‰)出现2次最低峰值,氧同位素(δ18O/‰)出现2次最高峰值;深度140.7 m湖相沉积碳同位素(δ13C/‰)和氧同位素(δ18O/‰)同时出现极低值.对应于渐新世/中新世界线深海沉积记录的Mi-1全球古气候事件.深度140.7～14.2 m湖相沉积碳氧同位素记录了Mi-1期后7次1.2 Ma天文周期的古气候旋回,深度62.6～9.86 m湖相沉积碳氧同位素记录了9次周期约17.4 ka的古气候旋回.根据湖相沉积碳氧同位素记录的古气候旋回,推断青藏高原北部五道梁盆地中新世早期古大湖发育时期为(24.1±0.6)Ma～(14.5±0.5)Ma,年均气温变化范围为19～21℃,平均约20.0℃. 相似文献
3.
系统分析青藏高原新生代中新世50余个沉积盆地的类型、构造背景、岩石地层序列,对青藏高原中新世构造岩相古地理演化特征进行分析和探讨。中新世,青藏高原海相沉积已经全面退出,全部转为陆相沉积,约23Ma时高原及周边不整合面广布,标志高原整体隆升。塔里木、柴达木及西宁-兰州、羌塘、可可西里等地区主体表现为大面积的构造压陷湖盆沉积。约17.2Ma左右,阿尔金山显著隆升,使柴达木盆地西叉沟一带再无生物礁灰岩出现,且在盆地西部出现了短暂的沉积间断。这一时期,柴达木盆地西部开始进入湖退期,而东南部则快速湖进;同时,大约17.7Ma索尔库里山间盆地初始凹陷形成。另外,高原腹地五道梁-沱沱河盆地受南部唐古拉山的挤压抬升,在16Ma左右结束了五道梁组的沉积,在可可西里—唢呐湖一带则再次凹陷接受唢呐湖组沉积,形成高原腹地的大型压陷湖盆。13～10Ma期间,藏南南北向断陷盆地的形成,是高原隆升到足够高度开始垮塌的标志;约8Ma以来,高原东北部几乎所有湖盆均进入湖退期,普遍出现冲积扇、辫状河和水下扇砂砾岩堆积。 相似文献
4.
青藏高原沱沱河盆地渐新-中新世沉积环境分析 总被引：10，自引：0，他引：10
沱沱河盆地保存着青藏高原内部至今发现最完整的渐新世至中新世连续沉积记录,由渐新世雅西措群(31.3～23.8 Ma)和早中新世五道梁群(23.8～21.8 Ma)组成,总厚度2 393 m.雅西措群主要为紫红色、砖红色砂岩、粉砂岩与泥岩韵律互层,五道梁群为一套内陆湖泊相泥灰岩、内碎屑灰岩和叠层石灰岩沉积.沱沱河盆地渐新-中新世沉积环境经历了3个阶段的演化:(1)早渐新世,以河流环境为主,古水流以北向为主,反映古气候条件比较干燥;(2)中晚渐新世,以湖泊环境为主,古水流以东北向为主,古气候条件相对温暖潮湿;(3)晚渐新世至早中新世,主要为湖泊环境,古水流转为南向,沉积岩性由雅西措群项部的砂泥岩互层为主转变为五道梁群的泥灰岩为主,反映当时的物源区发生重大转变,构造活动趋于稳定,古气候条件由温暖潮湿转为干燥.沱沱河盆地渐新-中新世气候和构造活动历史对于研究青藏高原早期隆升作用和全球气候变化都有重要意义. 相似文献
5.
青藏高原沱沱河盆地渐新-中新世沉积环境分析 总被引：13，自引：0，他引：13
沱沱河盆地保存着青藏高原内部至今发现最完整的渐新世至中新世连续沉积记录,由渐新世雅西措群(31.3～23.8Ma)和早中新世五道梁群(23.8～21.8Ma)组成,总厚度2393m。雅西措群主要为紫红色、砖红色砂岩、粉砂岩与泥岩韵律互层,五道梁群为一套内陆湖泊相泥灰岩、内碎屑灰岩和叠层石灰岩沉积。沱沱河盆地渐新-中新世沉积环境经历了3个阶段的演化:(1)早渐新世,以河流环境为主,古水流以北向为主,反映古气候条件比较干燥;(2)中晚渐新世,以湖泊环境为主,古水流以东北向为主,古气候条件相对温暖潮湿;(3)晚渐新世至早中新世,主要为湖泊环境,古水流转为南向,沉积岩性由雅西措群项部的砂泥岩互层为主转变为五道梁群的泥灰岩为主,反映当时的物源区发生重大转变,构造活动趋于稳定,古气候条件由温暖潮湿转为干燥。沱沱河盆地渐新-中新世气候和构造活动历史对于研究青藏高原早期隆升作用和全球气候变化都有重要意义。 相似文献
6.
通过对青藏高原沱沱河盆地五道梁组湖相沉积环境的分析,尝试通过湖相沉积地层记录提取气候变化信息,探索高原腹地中新世古环境变化特点。通过对五道梁组岩石类型及沉积特征研究,识别出了洪积平原、浅湖、滨湖、深湖及盐湖5个沉积相类型。参考现代湖泊特征与古代研究实例,探讨了研究区湖相碳酸盐岩的沉积机制。根据剖面岩相标志及地层叠置样式,证实五道梁组沉积期古湖泊经历了3次由低水位变为高水位的旋回性变化,湖泊最低水位期以石膏层的出现为标志,高水位期发育洪泛泥岩沉积;初步认为五道梁组沉积发育在一个干湿交替的气候期,湖水位变化和湖平面升降主要受气候控制,而构造沉降和湖缘断块隆升是次要控制因素。 相似文献
7.
可可西里盆地早渐新世雅西措群沉积环境分析及古气候意义 总被引：18，自引：3，他引：15
可可西里盆地是青藏高原腹地最大的第三纪沉积盆地,第三纪沉积地层包括早始新世 -早渐新世风火山群、早渐新世雅西措群、早中新世五道梁群。其中,雅西措群为紫红色、砖红色泥岩、含膏泥岩与紫红色粉砂岩、细砂岩韵律互层,夹白色石膏薄层和石膏结核层,沉积厚度为 6 70.0m,沉积环境主要由河流和湖泊环境组成,并以湖泊环境为主,古水流方向反映盆地沉积中心逐渐向东向北迁移。雅西措群中石膏层的突然大量出现发生在底部地层距今约32.0Ma,体现了渐新世最早期的全球变冷变干事件在青藏高原北部的记录。 相似文献
8.
可可西里西段羊湖盆地沉积、构造特征及其动力学意义 总被引：1，自引：0，他引：1
对可可西里西段新生代盆地缺乏了解是导致该区新生代地质演化存在争议的重要原因.本文以沉积学和构造变形分析为主要手段,对可可西里西段羊湖盆地时代、充填序列、物源区和变形特征进行了分析,结果表明,羊湖盆地新生界沉积厚度大于1302m,主要由下部雅西错组冲积扇相碎屑岩和上部五道梁群湖泊相碳酸盐岩组成,其岩石组合和充填序列与可可西里东段具有一致性,同时古流向和碎屑锆石U-Pb年代学分析显示盆地物源来南部的羌塘地块,盆地形成演化受南部褶皱冲断带制约,盆地构造变形强烈,沿褶皱冲断带和羊湖盆地地壳分别发生51％和41％的缩短.沉积充填结构和变形特征表明,羊湖盆地与东段可可西里盆地具有相同的演化历史和性质,预示青藏高原中部在渐新世-中新世在存在一个大的、统一的可可西里盆地. 相似文献
9.
青藏高原湖相沉积碳氧同位素、海拔高度与年均气温存在函数关系。对青藏高原南部14个不同海拔高度的第四纪湖相沉积露头,在剖面不同部位采集了35个湖相沉积样品,结合海拔高度与年均气温的相关分析,建立了湖相沉积碳氧同位素古海拔高度计。再对青藏高原南部、青藏高原北部、东昆仑南部和柴达木盆地不同地点出露的渐新世、中新世早中期、上新世—早更新世湖相沉积地层,分别取样进行碳氧同位素分析,计算不同时期的古年均气温和古海拔高度。结果表明,青藏高原大部分地区中新世早中期整体隆升至海拔约4000m高度,五道梁—东昆仑南部中新世早中期整体隆升至海拔约3500m高度,柴达木盆地中新世早中期隆升至海拔约2500m高度。这些资料对认识青藏高原隆升时代和气候环境演化具有重要意义。 相似文献
10.
松嫩平原南部腰井子古湖盆的发现与古环境信息 总被引：1，自引：1，他引：0
我们在进行松嫩平原湖泊古环境研究时, 根据卫星影像和实地考察发现松嫩平原南部存在一个大型古湖盆, 其规模之大与目前几乎消亡殆尽的状况形成了强烈的反差。古湖盆的湖相沉积和生物演替, 对东北平原古生态和古气候的重塑及湖盆土地利用的研究具有重要意义。 古湖盆位于“向乌”沙带和乾安高地之间, 呈卵圆形。其地理坐标为44°34′～44°42′N, 123°25′～123°41′E, 东西长约20km, 南北宽约15km, 湖盆面积约210km2。湖底地势东南高、西北低, 海拔多在140～142m之间。西北部有5个残留的湖泊, 面积最大的一个只有2.5km2, 其余多不足1km2。湖底植被主要为芦苇群落和羊草草甸群落。 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.
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
14.
15.
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
16.
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
17.
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
18.
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
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