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1.
大兴安岭北部的漠河盆地广泛发育中生界二十二站组砂岩,其形成时代一直备受争议.首次利用碎屑锆石LA-ICP-MS U-Pb法测年对其形成时代作出较为精确的限定,并结合地球化学特征对其物源区及大地构造背景进行了探讨.研究结果表明,二十二站组砂岩碎屑物磨圆度较低、分选差,表现出源区相对不稳定,快速剥蚀、搬运及沉积的特征.锆石颗粒粗大,具有清晰的震荡环带,Th/U值为0.35~1.07,为典型的岩浆锆石.测年结果显示,90个测点年龄主要分布在3个群落:152~170Ma,峰值年龄约为158Ma,这一年龄区间揭示了二十二站组沉积成岩的下限为晚侏罗世;179~193Ma,峰值年龄约为190Ma;205~214Ma,峰值年龄约为210Ma.3个年龄峰值为蒙古-鄂霍茨克洋演化过程中一系列岩浆活动的地质记录,其中210Ma与190Ma峰值年龄与盆地南缘额尔古纳地块晚三叠世、早侏罗世的岩浆事件相吻合,而158Ma峰值年龄则对应于盆地北缘晚侏罗世的岩浆事件.主、微量元素构造判别图解揭示其物源区具有活动大陆边缘的特征,同时锆石定年数据显示其没有任何前中生代的碎屑物,暗示了该3期岩浆岩均形成于额尔古纳地块北缘的中生代活动大陆边缘环境,并为二十二站组的形成提供了主要碎屑物质.由此说明,二十二站组砂岩形成于晚侏罗世蒙古-鄂霍茨克洋闭合后的造山过程中,漠河盆地南北两侧物源区快速剥蚀、快速搬运与快速沉积的环境. 相似文献
2.
漠河盆地位于兴蒙造山带北东端、额尔古纳地块北部。通过对漠河组开展碎屑锆石测年、岩石地球化学、现代地层学、古生物和重矿物研究, 探讨其沉积时代、物质来源和大地构造背景, 为研究漠河盆地演化提供科学依据。根据岩石地球化学、重矿物组合ATi(89.51~100.00, 平均98.69)和GZi(39.76~100.00, 平均64.50)指数分析: 漠河组主要产于活动大陆边缘和大陆岛弧背景下, 物源为上地壳长英质岩石、变质岩和沉积岩, 并混有深部即下地壳或地幔的基性岩; 岩石CIA(50.35~60.37, 平均53.50)和ICV指数(0.91~1.79, 平均1.40)及Rb/Sr(0.08~0.67)和Th/U(5.05~5.81, 平均5.55)值指示漠河组源区母岩经历了较弱程度的风化过程; 重矿物ZTR指数反映物源碎屑具有近源搬运特征; 漠河组中发现早侏罗世—早白垩世古植物化石, 结合碎屑锆石LA-ICP-MSU-Pb年龄(最小年龄为156±3Ma), 厘定漠河组沉积时代为晚侏罗世; 碎屑锆石年龄集中在3个时期: 1841~2462Ma(n=4, 古元古代)指示额尔古纳地块存在古元古代结晶基底; 311~480Ma(n=56)是额尔古纳地块与西伯利亚板块拼合造山后的伸展背景下花岗质岩浆形成的记录; 156~242Ma(n=48)是蒙古-鄂霍茨克洋俯冲于额尔古纳地块背景下岩浆侵入的证据。 相似文献
3.
漠河盆地位于蒙古?鄂霍茨克缝合带(MOSB)东段南缘,是研究蒙古?鄂霍茨克洋东段演化的绝佳窗口.本文对漠河盆地东缘出露的绣峰组砂岩进行详细的岩相学、U-Pb锆石定年和主微量元素地球化学分析,综合前人研究成果,限定了蒙古?鄂霍茨克洋乃至中亚造山带东段演化历史.结果表明,绣峰组砂岩碎屑物磨圆度较低、分选差,表现出近源剥蚀的特点;U-Pb锆石定年共获得217个谐和年龄,可划分为3个年龄组,其峰值均与盆地南缘额尔古纳地块的岩浆事件相吻合,其中最年轻的碎屑锆石206Pb/238U年龄加权平均值为158±2 Ma(N=5);样品相对富集大离子亲石元素(LILEs)和轻稀土元素(LREEs),亏损高场强元素(HFSEs)和重稀土元素(HREEs),具有明显的Eu负异常.样品源岩为上地壳长英质岩石,形成于大陆岛弧的构造环境,源区可能为漠河盆地南侧的大陆岛弧、额尔古纳地块以及盆地的古老基底.综上所述,绣峰组的最大沉积年龄为晚侏罗世,物源区构造背景为活动大陆边缘的大陆岛弧环境,形成于晚侏罗世蒙古?鄂霍茨克洋向南俯冲、闭合造山的构造背景下,指示在绣峰组沉积时期(约158 Ma),蒙古?鄂霍茨克洋仍处于俯冲阶段,尚未完全闭合.综合前人研究成果,推断蒙古?鄂霍茨克洋最终闭合的时间可能在晚侏罗世至早白垩世之间. 相似文献
4.
大兴安岭北部漠河盆地额木尔河群自下而上由绣峰组、二十二站组、漠河组和开库康组组成, 目前对额木尔河群形成时代还存在不同的认识。绣峰组含砾粗砂岩及二十二站组碎屑岩中流纹质凝灰岩夹层激光探针(LA-ICP-MS)锆石U-Pb测年结果表明, 绣峰组含砾粗砂岩中的碎屑锆石U-Pb年龄变化于距今2195~163 Ma之间, 暗示了源区有古元古代基底存在, 这一年龄数据与盆地周缘分布的基底岩石时代相吻合。碎屑锆石中5个最年轻锆石的206Pb/238U年龄加权平均值为167±2 Ma, 反映绣峰组沉积下限为中侏罗世中期; 二十二站组流纹质凝灰岩岩浆锆石206Pb/238U年龄加权平均值为148±2 Ma, 由此限定二十二站组形成时代为晚侏罗世晚期。锆石U-Pb年龄数据反映额木尔河群沉积时间为中-晚侏罗世, 这一认识对恢复漠河盆地形成演化历史及油气资源勘查提供了新的证据。 相似文献
5.
内蒙古伊敏地区下石炭统红水泉组砂岩物源分析及其构造意义 总被引:2,自引:0,他引:2
碎屑沉积物成份与源区构造环境、构造背景及源区岩石性质密切相关。通过对伊敏地区红水泉组砂岩样品进行砂岩碎屑颗粒成分统计、地球化学特征及碎屑锆石LA--ICP --MS U--Pb 年代学等物源分析方法,确定红水泉组砂岩为长石岩屑砂岩,物源区构造背景主要为大陆岛弧环境,其物源类型为切割型岛弧。红水泉组砂岩中最年轻的碎屑锆石年龄为338 ± 3 Ma,该年龄值表明红水泉组形成的时代为早石炭世密西西比中期的韦宪阶或之后。903 ~ 1 676 Ma 的分散元古界锆石年龄和~ 780 Ma 新元古代锆石年龄峰值,可能反映南蒙古微板块基底年龄信息。~ 500 Ma 和~ 380 Ma 的年龄峰值指示源区可能经历了多期岩浆事件: ~ 500 Ma 的岩浆锆石物源可能来自额尔古纳与兴安地块闭合相关的后造山花岗岩, ~ 500 Ma 的变质锆石可能来自变质基底, ~ 380 Ma 的物源可能反映额尔古纳-兴安地块与松嫩地块至少在晚泥盆世开始碰撞拼贴,并导致该区存在一个晚泥盆世-早石炭世的岩浆弧。 相似文献
6.
大兴安岭北部漠河盆地内广泛发育二十二站组,其形成时代及物质来源一直以来备受争议.本文在野外地质调查及岩相学的基础上,利用碎屑锆石LA-ICP-MS U-Pb法测年,并结合岩石地球化学等方法,探讨了二十二站组形成时代、物源区大地构造环境及沉积物来源.测年结果显示132个测点年龄主要分布在4个群落,分别为508.3~492.3 Ma;486.9~435.5 Ma;278.3~254.2 Ma;209.5~178.1 Ma.本次获得二十二站组最小碎屑锆石年龄为178.1 Ma,并结合漠河盆地东西部碎屑锆石的年龄,综合认为二十二站组形成时代应为中晚侏罗世.地球化学分析结果显示,二十二站组砂岩的稀土元素与活动大陆边缘的稀土元素曲线吻合较好,且相对亏损高场强元素(Nb和Ta)和大离子亲石元素(Ba和Sr),相对富集高场强元素(La、Th、Zr、Hf),地球化学特征与活动大陆边缘相似.综合古流向、源区母岩分析、碎屑锆石测年分析、微量元素特征等诸多因素,本次研究认为本区二十二站组砂岩的母岩主要来源于盆地南缘广泛分布的前中生代沉积-变质基底(兴华渡口岩群、佳疙瘩组、额尔古纳河组等)及各期中酸性火成岩. 相似文献
7.
大兴安岭富林地区早古生代碎屑锆石年代学对基底隆升时间的制约 总被引:1,自引:0,他引:1
对大兴安岭富林地区早古生代大伊希康河组、黄花沟组、红水泉组沉积岩进行了系统的碎屑锆石年代学研究,结果表明:①大伊希康河组的碎屑锆石的年龄在458±4~470±4Ma之间,与区域上的多宝山岛弧的火山岩年龄相一致,暗示着额尔古纳地块在早-中奥陶世大伊希康河组沉积时还未隆起;②黄花沟组碎屑锆石年龄谱为431±4~2227±24Ma,与区域上的额尔古纳地块所呈现的几组热事件年龄相一致,表明早志留世黄花沟组接受沉积时额尔古纳地块已经隆升至地表,为周缘盆地提供物源;③红水泉组的碎屑锆石测定年龄值为283±4~780±7Ma,其中283±4Ma为区域上的晚石炭世侵入岩热事件响应的年龄,多数碎屑锆石的测得年龄为333±3~343±3Ma,表明该套沉积物接受沉积时间的下限为333±3Ma;此时,物源区额尔古纳地块的新太古代-古元古代结晶基底已剥蚀殆尽。另外,利用岩石地球化学方法与推测的物源区进行了尝试性的对比研究。 相似文献
8.
对大兴安岭北部漠河盆地中侏罗统漠河组砂岩进行了碎屑锆石LA-ICP-MS U-Pb年龄测试,获得的碎屑锆石U-Pb年龄为1425~170 Ma,反映了中侏罗时期漠河盆地源区的复杂性。该时期漠河盆地物源主要有:中元古代变质火山岩,碎屑锆石年龄1425~1064 Ma;新元古代变质侵入岩,碎屑锆石年龄888~550 Ma;寒武—奥陶纪变质表壳岩与深成侵入岩,碎屑锆石年龄517~441 Ma;石炭—二叠纪侵入岩,碎屑锆石年龄327~252 Ma;三叠纪—中侏罗世侵入岩,碎屑锆石年龄250~170 Ma。这一测试数据与盆地现在南缘分布的地质体的时代基本对应,说明盆地的物源主要来自南部的中元古代—中侏罗世地质体,碎屑锆石中最小年龄为170 Ma,反映漠河组沉积下限不早于中侏罗世早期。这一成果对研究漠河盆地源区的物质组成、盆地沉积年代和油气成藏条件提供了新的素材。 相似文献
9.
北祁连山西段北大河岩群碎屑锆石SHRIMP U-Pb年代学研究 总被引:10,自引:0,他引:10
白云母石英片岩中碎屑锆石的成因矿物学研究及SHRIMP U-Pb同位素年龄测定表明,北大河岩群变质沉积岩的蚀源区存在1400~3035Ma构造热事件,除了年龄为约2457Ma的变质事件外,主要表现为岩浆事件,其中以1800Ma左右的岩浆事件最为强烈,1400~1700Ma事件次之,中-新太古代的岩浆事件也比较明显;北大河岩群可能遭受过863Ma左右的变质作用影响,其沉积岩的沉积作用发生于1400Ma(最小的碎屑锆石年龄)至863Ma(变质年龄)之间,而不是前人所认为的古元古代;根据46%的碎屑锆石为1800Ma左右这一事实,最起码可以肯定北大河岩群的沉积年龄新于1800Ma;北大河岩群的蚀源区存在中-新太古代的古老陆壳。同时,北大河岩群碎屑锆石年龄资料也为朱龙关群蛇绿岩的形成时代提供了有力的制约:朱龙关群蛇绿岩很可能形成于早古生代,而非中元古代早期。 相似文献
10.
东昆仑东段巴隆地区变复成分砾岩层锆石U-Pb年龄及其地质意义 总被引:1,自引:0,他引:1
东昆仑东段巴隆地区哈图沟出露一套变质—变形的沉积地层,其北部为变复成分砾岩段、南部为变细碎屑岩段。根据变复成分砾岩段砾石成分统计、砾石的分选系数(1.24~1.42)及砾石的砾度等粒性特征得出该套变复成分砾岩地层为近源快速堆积的产物。利用LA-MC-ICP-MS锆石U-Pb微区测年技术,对变复成分砾岩段绢云钠长石英片岩的碎屑锆石进行U-Pb同位素测年,测试结果表明,碎屑锆石年龄谱可明显划分为6组:1南华纪—震旦纪年龄组,751~602Ma,峰值为674Ma,该组锆石年龄与东昆仑造山带新元古代中—晚期岩浆事件的年龄相对应,并且与Rodinia超大陆裂解事件相关,该组锆石中最小的年龄为602Ma,表明沉积地层形成时代应晚于602Ma;2中元古代晚期—新元古代中期年龄组,1146~783Ma,出现三个峰值,分别为788Ma、947Ma和1115Ma,该组锆石年龄与东昆仑造山带中元古代晚期—新元古代中期岩浆事件大致相对应,代表东昆仑地区响应了全球尺度的Rodinia超大陆的汇聚事件,且证实了柴达木—祁连—东昆仑等地(陆)块前寒武纪的演化特点与塔里木及扬子克拉通非常相似;3中元古代晚期年龄组,1399~1180Ma,峰值为1318Ma,该组锆石年龄可能与东昆仑构造带中元古代晚期岩浆事件相关;4中元古代早期年龄组,1712~1553Ma,峰值为1556Ma,该年龄谱段代表了源区在中元古代早期存在着一期热事件;5新太古代晚期—古元古代早期年龄组,2530~2347Ma,峰值为2518Ma,该组锆石年龄与东昆仑造山带内新太古代晚期—古元古代早期岩浆事件年龄大致相对应,表明东昆仑造山带新太古代晚期—古元古代早期岩浆物质也为哈图沟变质地层提供了物源;6太古宙年龄组,3230~2763Ma,表明变复成分砾岩的物源区可能存在古太古代陆核。通过对变质岩系的碎屑锆石年龄和物源特征的分析研究,认为这套变质的沉积地层并非前人所划归的泥盆系牦牛山组,其形成时代应归属于晚震旦世。砾石成分统计和年代学测试结果表明,巴隆地区哈图沟变复成分砾岩层物质主要来源于东昆仑造山带的前寒武纪白沙河岩组、小庙岩组、万宝沟岩群等变质地层和中、新元古代深变质的花岗质片麻岩等。 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:16,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.
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
15.
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.
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
20.
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