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1.
从冰川剥蚀作用看念青唐古拉山脉(中段)的隆升   总被引:3,自引:2,他引:1  
通过对念青唐古拉山主峰地区第四纪冰碛地层划分与同位素测年,发现主峰地区的第四纪冰川分别形成于700~600kaBP、200~140kaBP和70~30kaBP三个时段,指示了自中更新世以来念青唐古拉山中段开始大规模隆升,冰川活动加剧,并堆积了相应的冰碛物。根据念青唐古拉山主峰地区基岩地层与岩性的空间分布、不同火成岩和变质岩组合的形成深度和不同冰期冰碛物砾石成分统计研究,发现冰川对基岩剥蚀与念青唐古拉山中段隆升过程有着明显的对应关系。本文从念青唐古拉山主峰地区的基岩地层的岩石成分和分布的研究,及其对山脉隆升与冰碛物成分的关系等方面,分析了念青唐古拉山脉的切割及其对山脉隆升的反映。念青唐古拉山主峰地区的隆升过程可较好地与青藏高原的隆起相对比,它应是青藏高原隆升的响应。  相似文献   

2.
念青唐古拉山西布冰川区的冰碛层   总被引:12,自引:1,他引:12  
念青唐古拉山西布冰川区冰碛物的研究表明,在700-500kaBP以来的更新世期间经达了3次冰期,全新世期间经历了2次冰期和1次寒冷期,形成了可以与青藏高原及邻区相对比的冰碛物系列,指示了念青唐古拉山至少自中更新世以来一直处于冰冻圈中。冰碛物中砾石成分的规律性变化反映了念青唐古拉山第四纪期间处于强烈隆升状态,冰碛物是盆地同伸展断陷期的堆积物。根据冰碛物与念青唐古位山南东麓正断层间的关系可以得出:中更新世以来构成念青唐古拉山南东麓正断层带的主要断层(F2)的平均垂直活动速率为0.5-1.25mm/a,左旋走滑  相似文献   

3.
第四纪冰川测年研究新进展   总被引:15,自引:4,他引:11  
周尚哲  李吉均 《冰川冻土》2003,25(6):660-666
第四纪冰川研究经历了与经典的阿尔卑斯冰期模式对比,与深海氧同曲线位素对比和技术测年3个阶段.由于近年测年技术的应用,国际上晚第四纪冰川作用研究有喜人的进展,2003年召开的第16届INQUA再度出现第四纪冰川热.我国青藏高原第四纪冰川研究近年也取得了重要进展,初步确定高原各山脉发生最早冰川作用的时间是不同的:天山和祁连山在450~470kaBP的氧同位素12阶段,横断山的沙鲁里山和玉龙山在560kaBP左右的16阶段,东西昆仑山在约700kaBP左右,念青唐古拉山在680kaBP.表明在青藏高原昆 黄运动后的全球历次冰期中,高原各部相继发育冰川,成为了冰期中地球中低纬度山地冰川的王国.  相似文献   

4.
西藏阿伊拉日居山南麓第四纪冰川沉积物及其ESR年龄测定   总被引:5,自引:2,他引:5  
在西藏札达盆地北缘阿伊拉日居山南北两麓及切割山脉的各沟谷中, 分布着 4 套第四纪冰川与冰水沉积物, 其冰川沉积物的电子自旋共振(ESR)测年结果分别为 1 161~730 ka BP、319~336 kaBP、211 ka BP和105~15 ka BP. 测年结果表明, 在札达盆地北缘阿伊拉日居山南麓所发生的 4 次冰川作用, 其形成时期分别为早更新世晚期、中更新世中晚期、中更新世晚期和末次冰期.  相似文献   

5.
唐古拉山地区第四纪冰川作用与冰川特征   总被引:4,自引:2,他引:2  
自中更新世以来,唐古拉山地区发生过3次更新世冰川作用(即昆仑冰期、倒数第二次冰期和末次错冰期)和2次全新世晚期冰进(即新冰期和小冰期冰进).昆仑冰期(最大冰期)发生在中更新世早期(0.80~0.60MaBP),不仅是本区最早的一次冰期,而且也是冰川规模最大的一次冰期,当时的冰川规模比现代冰川大16~18倍;倒数第二次冰期发生在中更新世晚期(0.30~0.135MaBP),比现代冰川大13~15倍;末次冰期发生在晚更新世晚期,应分为末次冰期早冰阶(75.0~58.0kaBP)和晚冰阶(32.0~15.0kaBP,23.0kaBP时达到极盛),但在唐古拉山地区截止目前还未找到早冰阶的冰川遗迹,因此,只对末次冰期的晚冰阶(LMG)进行了探讨.LMG时,冰川规模比现代冰川大10倍;新冰期发生在全新世高温期后,冰碛物的14C测年为(3540±160)aBP,冰川规模略大于现代冰川;小冰期发生在15~1世纪,冰川规模已接近于现代冰川.由于青藏高原的上升,对高原腹部地区引起的干旱化过程和水分严重不足,使唐古拉山地区的冰川自昆仑冰期以来,冰川规模一次比一次明显的减小.  相似文献   

6.
辽东青城子矿集区金、银成矿时代及地质意义   总被引:20,自引:0,他引:20       下载免费PDF全文
为确定辽宁青城子矿集区金、银的成矿时代 ,分别以含金硅化岩和含银网脉状石英晶体内流体包裹体为对象 ,应用Rb_Sr法测得金、银成矿的等时线年龄为 (2 33± 31)Ma~ (2 34± 14 )Ma ;作为对Rb_Sr法测年结果的验证 ,又以与贵金属矿石矿物共生的热液石英为对象 ,用40 Ar/3 9Ar快中子活化法测得坪年龄tp=(2 38.78± 0 .74 )Ma~ (2 38.80± 0 .6 0 )Ma,等时线年龄ti=(2 39.4 6± 1.13)Ma~ (2 4 0 .35± 0 .88)Ma。Rb_Sr和40 Ar/3 9Ar两种方法的测年结果基本一致 ,与本区印支期岩浆活动时代〔2 17.6Ma~ (2 30 .7± 5 )Ma〕吻合。  相似文献   

7.
西藏当雄-羊八井盆地的第四纪地质与断裂活动研究   总被引:7,自引:2,他引:5  
在当雄-羊八井盆地进行的详细地质填图工作表明,该盆地中堆积了上新世或早更新世以来多套不同成因的沉积物。其中最显著的是形成于约700~500kaB.P.、250~125kaB.P.和75~12kaB.P.等三个阶段的冰川和冰水沉积物,它们指示念青唐古拉山地区在中更新世以来曾有过三次冰期。对念青唐古拉山东南麓断裂带的研究表明,该断裂带包含了三条次级断层带,它们具有不断向盆地内部迁移和多期活动的特点,其中中更新世以来的几次重要活动分别发生在700~500kaB.P.、350~220 kaB.P.、140kaB.P.和70~50kaB.P.。断裂带错动中更新世以来地层所形成的断层崖高度随着地层时代的变新发生系统地减小,指示该断裂的垂直活动速率介于0.4mm/a~2mm/a之间,其中第四纪期间的长期的平均垂直活动速率为1.1±0.3mm/a,而全新世期间的垂直活动速率为1.4±0.6mm/a.   相似文献   

8.
甘孜绒坝岔古冰川演化与黄土古土壤对比研究   总被引:6,自引:3,他引:6  
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。  相似文献   

9.
王杰  周尚哲  唐述林 《冰川冻土》2007,29(1):149-155
在野外综合考察的基础上,对唐古拉山垭口地区末次冰期的冰碛漂砾(或有冰川擦痕的露头)进行了宇生核素10Be暴露年龄的测定,得到(16.1±1.7)ka BP、(31.9±3.4)ka BP、(41.4±4.3)kaBP和(66.8±4.3)ka BP 4个测年数据.结合前人对本地区研究和测年的资料,确定该区更新世经历了4次较大规模的冰川作用:中更新世晚期的倒数第二次冰期、晚更新世中晚期的末次冰期早冰阶、间冰阶和晚冰阶,依次与MIS6、MIS4、MIS3和MIS2阶段对应;全新世经历了2次小的冰进:新冰期和小冰期,它们的时代与青藏高原其它地区新冰期和小冰期的时代基本一致.末次盛冰期的冰川范围十分有限,并且MIS3阶段的冰进规模远远超过了末次盛冰期.早期考察中所命名的唐古拉冰期和巴斯错冰期的时代是中更新世晚期(MIS6)和末次冰期早冰阶(MIS4),扎加藏布冰期的冰碛可能是末次冰期的冰碛叠加在倒数第二次冰期的冰碛物之上,而又经过后期作用改造而形成的一套冰碛.在该区老的冰碛物上没有测定出MIS6阶段之前的年代数据,可能是由后期的破坏或采集的样品不够充分所致,因此对本区最早冰川作用的时代还有待于进一步深入研究.  相似文献   

10.
利用1999年ETM、2014/2015年GF-1为主的2期遥感影像作为数据源,采用人机交互解译的方法完成了2期冰川编目成果,并对最近15年(1999—2015)念青唐古拉山冰川变化进行分析。结果显示,从1999年至2015年间,念青唐古拉山脉冰川呈退缩趋势,以东段海洋型冰川退缩为主,西段亚大陆型冰川相对稳定。冰川总面积减少了56. 32km2,减少变化率为0. 67%;有10条冰川消失,减少变化率为0. 16%;冰储量减少5. 315 km3,减少变化率为0. 78%。调查结果还显示,念青唐古拉山地区冰川各朝向均呈退缩趋势,偏南向和东向冰川数量与面积减少大于偏北向和西向的;平均坡度在20°~35°范围的冰川数量和面积减少最多;海拔介于4 500~5 500 m区间的冰川面积退缩最明显。在恒河流域和萨尔温江流域的冰川消退最显著。总体上,不同规模冰川均有退缩,规模≤5. 0 km2的冰川是念青唐古拉山地区退缩最多的。冰川退缩与气候变化关系密切。选取念青唐古拉山脉附近3个气象台站,对最近50多年以来的年均气温和年降水量变化分析表明,自1961年以来,念青唐古拉山年均气温呈显著上升趋势,而降水量变化不一,有增有减。气温上升而降水减少,可能是导致念青唐古拉山地区东段冰川退缩的一个因素。  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.
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.
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   

15.
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   

16.
塘口水电站大坝基础座落在断层和裂隙较发育的龟裂纹灰岩上,岩体完整性差、透水性强,多年运行后,大坝灌浆廊道和排水廊道出现多处集中性漏水,为确保大坝安全和电站正常发电,根据渗漏性质和成因,采用对灌浆廊道补充帷幕灌浆,对排水廊道进行固结+帷幕+回填灌浆。通过灌浆处理后,效果良好,表明灌浆工程有效的将导致坝基渗漏的上下游的裂隙通道封闭,并顺利的经受了随后的汛期洪水考验,大坝安全得到保障。  相似文献   

17.
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.
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.
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   

20.
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   

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