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1.
《吉林大学学报(地球科学版)》2015,(Z1)
辽河盆地位于郯庐断裂带北段,地处华北陆块东部,是我国东部大型新生代含油气裂谷盆地。近年来,随着勘探和研究程度的不断深入,尤其对火山岩储层勘探获得重大突破后,盆地内火山岩的研究得到了更多的重视和关注。盆地断陷期发育的厚层始新统沙河街组三段火山岩是本区最为重要的油气储集层。有关这套火山岩的研究,已有的成果主要集中在火山岩油气藏勘探开发和年龄测定方面,而涉及火山岩成因和形成动力学机制的研究较为欠缺。因此,本文利用井下样品对辽河盆地始新世火山岩进行了相关研究。辽河盆地始新统沙河街组三段火山岩主要由基性端元的玄武质岩石和中性端元的粗面质岩石构成,上部和下部为玄武质岩石,中部则主要发育粗面质岩石及少量玄武质岩石夹层。玄武质岩石的w(Si O2)为47.75%~53.71%,w(K2O)较低(0.64%~1.82%),全碱质量分数低—中等(3.42%~6.80%),较高的w(Mg O)(3.78%~9.73%)和Mg#(44~65),Eu呈正异常(1.03~1.26);总体富集高场强元素,相对亏损大离子亲石元素,具明显的Ba、Sr和Zr正异常。粗面质岩石具有较高的w(Si O2)(55.35%~60.70%)、w(K2O)(3.95%~9.46%)和全碱(8.41%~12.70%)质量分数,相对低的w(Mg O)(0.44%~1.69%)和Mg#(17~45),其中多数岩石具有负Eu异常(δEu=0.37~0.77),部分没有明显Eu异常(0.81~0.96);富集大离子亲石元素、亏损高场强元素,Sr、Ti和Ba强烈亏损。玄武质岩石的初始87Sr/86Sr值为0.703 3~0.704 2,εNd(t)=3.56~5.86,显示岩浆源区具有亏损地幔的特征;粗面质岩石的初始87Sr/86Sr值为0.703 5~0.704 5,εNd(t)=3.25~4.46,与玄武质岩石几乎完全一致,暗示玄武质岩石和粗面质岩石具有相同的岩浆源区。根据本文对辽河地区始新世火山岩的综合研究,结合华北东部古近纪时期的构造环境及岩石圈演化特征,我们认为:本区玄武质岩石来源于板内软流圈地幔的上涌,同时有来自俯冲的大洋岩石圈成分的加入,是软流圈地幔上涌和岩石圈地幔减薄过程中,软流圈地幔较低程度部分熔融的产物,并经历了橄榄石和辉石的分离结晶作用。玄武质岩浆上升到较浅部位后进一步发生橄榄石、辉石、斜长石和磁铁矿等的分离结晶作用而形成粗面质岩石,地壳物质的混染作用不显著。 相似文献
2.
沂沭断裂带中南段钾质火山岩的元素地球化学与Sr-Nd-Hf同位素组成及其对岩石成因的制约 总被引：2，自引：0，他引：2
本文以沂沭断裂带中南段莒南-大店一带的钾质火山岩为对象,系统研究了它们的岩石学、元素地球化学和Sr-Nd-Hf同位素组成特征,据此探讨了源区地幔富集机制及岩石成因。莒南钾质火山岩主要为一套安粗质火山-潜火山岩组合,大店多发育粗面质火山岩,二者的锆石LA-ICP-MS U-Pb年龄基本一致,均约为118Ma。在化学组成上,这套火山岩均偏碱性,里特曼指数(σ)介于4.10~5.07,且富钾(K_2O=4.21%~5.77%),在SiO_2-K_2O和K_2O-Na_2O关系图上,均投影在钾玄岩系区。安粗质和粗面质火山岩均富大离子亲石元素(Cs,Rb,Th,U,Pb)和轻稀土元素,贫高场强元素(Nb,Ta,P,Ti),但粗面质火山岩具较显著的Ba、Eu负异常,且轻重稀土比值较低。二类火山岩均具有富集且较均一的Sr-Nd同位素组成(I_(Sr)=0.7086~0.7091,ε_(Nd)(t)=-16.9~-18.2),锆石ε_(Hf)(t)值均为显著的负值(安粗质岩:-22.3~-24.3,粗面岩:-19.7~-23.6)。元素和同位素组成的综合分析表明,区内钾质火山岩的源区地幔极可能遭受了因扬子板块深俯冲和华北克拉通岩石圈拆沉等多次富集事件的影响。至早白垩世,随着郯庐断裂引张的加剧,诱发了软流圈地幔上涌,同时在断裂减压作用的影响下,促使了这一经叠次改造的富集地幔的部分熔融,由此产生的岩浆经进一步分异演化,导致了区内钾质火山岩的形成。 相似文献
3.
安徽庐枞中生代富钾火山岩成因的地球化学制约 总被引：74，自引：7，他引：74
庐枞中生代火山岩产于下扬子断裂坳陷带的继承式火山盆地中，主要为一套以粗面玄武岩－玄武粗安岩－安粗岩－粗面岩为主体的偏碱质中基性岩石组合。化学成分上具有富碱、富钾、富轻稀土及大离子亲石元素（如Rb、Th、Pb)和贫高场强元素（如Nb、Ti)等特点。在郯庐断裂中南段及其邻近地区的中生代火山岩中，庐枞盆地火山岩的特征最接近钾玄岩系火山岩。这套火山岩具有较高的ISr值（0.70570-0.70653)及偏低的εNd(t)值（－5.01～-9.96)。火山岩产出地质背景的全面分析及元素－同位素的综合示踪，排除了岩浆上升过程中存在强烈的地壳物质的混染，富钾火山岩的岩浆源区应为受俯冲板片析出流体交代作用所形成的富集地幔（EMI），岩石主要起源于富集型地幔的部分熔融。 相似文献
4.
长白山区二道白河流域早更新世玄武质熔岩的成因 总被引：2，自引：1，他引：1
采用岩石化学和同位素分析方法,研究了二道白河流域早更新世玄武质熔岩的成因。玄武质熔岩由钠质拉斑玄武岩和钾质粗面玄武岩、玄武质粗面安山岩组成。它们的REE分配形式比较相近,表明它们来自共同的源区。Sr、Nd、Pb同位素示踪表明,二道白河流域早更新世玄武质熔岩岩浆源区接近于似原始地幔。它们的Mg#=100Mg O/(Mg O+Fe O)低于中国东部新生代玄武岩原始岩浆的Mg#(60~68),Ni(27.76×10-6~200.6×10-6)低于原始地幔,Rb/Sr(0.05~0.09)、Ba/Rb(15.64~264)高于原始地幔,说明这些岩石不是源自原始地幔。玄武质熔岩的DI变化于42~67,具有高Ca、高Sr、Eu正异常,微量元素图解显示玄武岩保留部分熔融趋势,粗面玄武岩、玄武质粗安岩具有结晶分异趋势,岩浆上升过程中发生了不同程度的地壳混染作用。玄武质熔岩的Nb/Ta之比为14.8~15.8,与勘察加半岛深俯冲带火山类似。Nb/Ta-(Na2O-K2O)关系图解显示研究区玄武质岩浆的形成与俯冲板片的部分熔融有关。 相似文献
5.
以山东西部西董地区中生代青山群火山岩为研究对象,在进行系统的元素-同位素分析的基础上,探讨其岩浆源区和岩石成因,同时丰富该区域岩石地层的地球化学特征。西董青山群火山岩Si O2含量变化于52.8%~59.8%之间,主要为钙碱性系列岩石,岩石组合为玄武质粗面安山岩-玄武质安山岩-粗面安山岩,Mg O、TFe2O3、Mn O、Ti O2、Ca O与Si O2具有明显的负相关关系,Al2O3和Na2O与Si O2具有正相关关系;微量元素富集Rb、Ba、Th、U和K等大离子亲石元素,亏损Nb、Ta和Ti等高场强元素,稀土元素总量∑REE变化范围为100×10-6~187×10-6,(La/Yb)N比值范围为8.2~11.1,无明显的Eu异常(δEu=0.9~1.02);显示富集且均一的Sr-Nd同位素组成((87Sr/86Sr)t=0.7047~0.7050,εNd(t)=-16.5~-14.2)。西董青山群火山岩的Nd、Sr同位素组成与Si O2缺乏明显负相关关系,Nb/Ta与La/Nb之间不具有负相关关系以及Nb与Th之间具有正相关关系,指示岩浆在上升和演化过程中地壳混染作用对青山群火山岩岩浆化学组成的影响并不显著;火山岩Mg O含量明显高于玄武岩部分熔融形成的熔体,说明青山群中基性火山岩岩浆的形成过程可能与大陆地壳和地幔岩系之间的相互作用有关。综合分析表明,西董中生代青山群火山岩是大陆下地壳物质经拆沉作用于地幔环境中发生部分熔融,与上地幔岩石发生交代作用后进入地表形成。 相似文献
6.
中新生代频繁的岩浆活动是辽河盆地重要特征之一,东部凹陷作为各时期岩浆活动的中心,下第三系火山岩基本覆盖了整个凹陷。受构造运动差异影响,东部凹陷各地区不同时期岩浆活动强度不同,房身泡组火山岩分布最广,从沙三段到东营组沉积时期岩浆活动具有自中部向南、北转移的特征。岩石学和地球化学研究表明,主要火山熔岩类型为碱性玄武岩、粗面岩和辉绿玢岩;岩石化学组成上具有高碱、高铝和镁,较富集轻稀土元素,Eu异常不明显（δEu为0．70～1．05）,弱亏损Ti、P、Sr、Ta元素的特征。岩石εNd（t）和（N（^87Sr）／N（^86Sr））．组成分别为-2．8～2．8和0．7046～0．7067。综合研究表明,玄武质岩浆来源于岩石圈地幔,而粗面岩和辉绿玢岩可能源于幔源玄武质岩浆的分异,但辉绿岩受地壳物质污染较重;该火山岩形成于大陆裂谷环境,反映出早第三纪辽河盆地处于拉张构造背景。 相似文献
7.
宁芜地区中生代富钾和富钠火山岩的源区特征:岩石学和地球化学证据 总被引：2，自引：0，他引：2
宁芜中生代火山盆地广泛产出早白垩世中基性火山岩,钾质岩石主要为龙王山组英安岩、粗安岩,钠质火山岩主要为大王山组玄武粗安岩、粗安岩、英安岩以及钠质安山玢岩类。钠质辉石安山玢岩的锆石U-Pb年龄为128.9±1.9Ma,为早白垩世产物。稀土元素球粒陨石标准化配分曲线均表现为一致的平缓右倾型式,Eu负异常不明显,富集大离子亲石元素,亏损高场强元素,具Nb、Ta的负异常。钾质龙王山组火山岩总体Cs、Rb、Ba、Th、U等LILE含量较钠质大王山组火山岩和钠质安山玢岩高,并具有较高的Si、K,较低的Ca、Mg,高Rb/Sr,高Isr(0.70521~0.70857);钠质火山岩具有较低的Si、富Na、高Sr、低I_(sr)(0.70544~0.70768),Mg~#相对较高。钠质辉石闪长玢岩斑晶中有斜长石的矿物结构和成分不平衡现象,锆石Hf同位素特征为ε_(Hf)(t)=-6.2~+0.6,变化较大,指示岩浆混合过程。地幔源区可能是由中元古代俯冲板块释放出流体发生交代作用后形成的富集地幔,钾质火山岩地幔源区交代矿物可能以金云母为主,崆岭群TTG片麻岩为其地壳端元。而钠质火山岩地幔源区交代矿物可能以角闪石和单斜辉石为主,中元古上溪群变质基性岩或新生下地壳基性岩为其地壳端元。 相似文献
8.
庐枞早白垩世火山岩的地球化学特征及其源区意义 总被引：37，自引：1，他引：37
从中生代到新生代，华北东部岩石圈地幔发生了减薄以及地球化学性质置换, 而扬子地块东部中生代岩石圈地幔也表现出类似的过程，对中生代火山岩的地球化学研究有助于了解这一变化过程以及发生置换时的时空关系。庐枞火山岩出露于扬子地块东部，为一套包括粗玄岩–玄武粗安岩–粗面岩的富碱橄榄安粗岩系。研究了双庙组基性火山岩，这些岩石富集Rb，K，Sr，Th和轻稀土元素，亏损高场强元素。(87Sr/86Sr)i = 0.7060~0.7063，εNd(t )=-3.9~-6.2，(206Pb/204Pb)i=17.788~18.125，(207Pb/204Pb)i= 15.511~15.546，(208Pb/204Pb)i =37.735~38.184。在喷出地表过程中，火山岩没有受到明显的地壳物质混染，因此元素和同位素组成反映了地幔源区的地球化学特征。
其地幔源区具有同位素富集特征，表明火山岩源区曾受到地壳物质的影响，是富集地幔部分熔融的产物，并经历明显的结晶分异作用。庐枞火山岩的岩浆成分和源区特征反映该地区在晚中生代岩石圈地幔的伸展和软流圈地幔上涌的演化过程。 相似文献
9.
大兴安岭中生代火山活动构造背景 总被引：23，自引：1，他引：22
大兴安岭中生代火山岩主要为高钾粗面质火山岩, 属于一套碱质含量比较高的钙碱性火山岩系, 随时间从酸性向中基性方向演化。其元素地球化学特征和Sr、 Nd 同位素组成揭示火山岩具有壳源和幔源两部分源区特点, 玄武质岩石来源于相对未亏损的地幔, 中酸性火山岩则成因于地壳物质的混染或下地壳的重熔作用, 暗示火山岩的形成与陆内深部软流体上涌引起的壳幔相互作用有关。 此外, 本文还从火山活动中心的迁移,以及东邻洋陆板块之间的相互运动角度,阐述了大兴安岭中生代火山活动与大洋板块的俯冲作用无直接联系。 相似文献
10.
碧口群火山岩岩石成因研究 总被引：12，自引：1，他引：12
新元古代(846~776Ma)碧口群火山岩喷发于大陆板内裂谷环境。该火山岩系以基性火山岩为主,酸性火山岩次之,中性火山岩少见。根据岩石地球化学数据,碧口群裂谷基性熔岩总体上属于低Ti/Y(<500)岩浆类型。元素和同位素数据表明,碧口群基性熔岩的化学变化不是由一个共同的母岩浆的结晶分异作用所产生。它们极有可能是源于地幔柱源(εNd(t)≈+3,87Sr/86Sr(t)≈0.704,La/Nb≈0.7)。地壳混染作用对于碧口群裂谷基性熔岩的形成有重要贡献。我们的研究揭示,碧口群火山岩存在空间上的岩石地球化学变化。东部红岩沟和辛田坝—黑木林地区的碧口群基性熔岩以拉斑玄武岩为主,产生于幔源石榴子石稳定区的高度部分熔融。相反,西部白杨—碧口地区的碧口群基性熔岩的母岩浆则是形成于幔源的尖晶石-石榴子石过渡带:碱性熔岩是产生于部分熔融程度较低的条件下,拉斑玄武质熔岩则是产生于部分熔融条件较高的条件下。它们经受了浅层位辉长岩质(cpx+plag±ol)分离作用,化学变异较大。 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.
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.
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
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
20.
Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base. 相似文献