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1.
新疆达拉布特蛇绿岩带玄武岩地球化学特征:古亚洲洋与特提斯洋的对比 总被引：13，自引：7，他引：6
发育在我国北部的古亚洲洋构造域和西南部的特提斯构造域是中国境内最重要的两个构造体系,有关这两个构造域的地幔地球化学特征是揭示它们的演化与交接关系的重要课题之一。本文选择发育在新疆西准噶尔地区达拉布特蛇绿岩带中阿克巴斯套和大棍的枕状玄武岩进行了系统的岩石学和地球化学与Sr-Nd-Pb同位素地球化学研究,结果表明,达拉布特蛇绿岩带中枕状玄武岩具有N-MORB和E-MORB特征,可能形成于大洋中脊环境。岩石的~(87)Sr/~(86)Sr为0.682112～0.706040之间;~(143)Nd/~(144)Nd为0.512713～0.512879,ε_(Nd)(t)= 2.8～ 5.1,~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb的变化范围分别是18.341～20.085、15.541～15.651和38.292～40.534。将达拉布特玄武岩的微量元素特征比值、Nd-Pb同位素等与印度洋MORB和太平洋与北大西洋MORB,以及已知的特提斯和古亚洲洋地幔域进行对比表明,达拉布特蛇绿岩单元内MORB型玄武岩与特提斯构造域特蛇绿岩单元内MORB型玄武岩同位素特征一致,都显示了印度洋型的MORB特征。这意味着位于现今新疆西准噶尔地区的古亚洲洋地幔域没有显示出与特提斯不同的典型的太平洋和北大西洋的地球化学特征。 相似文献
2.
滇东师宗—弥勒带北段基性火山岩地球化学有其对华南大陆构造格局的制约 总被引：6，自引：2，他引：6
滇东地区的师宗－弥勒构造带是解决古特提期东延问题的关键，综合研究表明，该带是以多条断层为骨架，包容不同性质构造岩块的构造带。明显分隔两则不同岩石－构造组合、变质作用、岩浆活动。师宗－弥勒构造带北段的火山岩地球化学研究表明，其主要为碱性弱武岩，主元素以低TiO2、高Al2O3为特征，区别于高TiO2、低Al2O3特征的眉山大陆溢流玄武岩。高场强元素丰度类似于板内玄武岩平均丰度，Zr/Nb、Hf/Th值分别变化在5．6－13．5和0．9－1．3范围内，类似于板内玄武岩。球粒陨石标准化的稀土元素配分模式为LREE富集型，MORB标准化的微量元素配分型成为大隆起型，显示岩浆形成于板内裂谷构造环境。不活动元素协变关系也支持这一结论。同位素地球化学研究表明，岩石以低^143Nd/^144Nd、高^87Sr/^86Sr值为特征，类似于RioGrande裂谷玄武岩的同位素组成，εNd(t）值变化在＋0．9－＋3．2之间，显示岩浆源于轻微亏损地幔，并受到富集地幔物质影响。（^206Pb/^204Pb）i和（^207Pb/^204Pb）i和（^208Pb/^204Pb）i分别顷17．131－19．119，15．386－15．670和37．780－39．266之间，（^206Pb/^204Pb）i和（^207Pb/^204Pb）i具有正相关关系。△^206Pb/^204Pb和△^207Pb/^204Pb分别变化在5－24和21－61之间，显示本次研究的玄武岩来源于DMM和EMII混合组成的地幔，明显区别于具EMI特征的峨眉山玄武岩。地质、地球化学及年龄学综合分析研究表明，滇东师宗－弥勒带北段的基性火山岩晚古生代裂谷构造环境，指示华南大陆内部存在连通滇西特提斯的裂谷型深水海道。 相似文献
3.
西秦岭-松潘构造结古洋地幔地球化学特征及构造归属探讨 总被引：2，自引：0，他引：2
西秦岭-松潘构造结是中国大陆中重要的构造转换域,为探讨不同陆块及古洋幔的构造归属提供了非常有利的条件。该构造结早古生代蛇绿岩单元内变质玄武岩的地球化学特征表明:其源区不具有高场强元素(HFSE)相对于大离子亲石元素(LILE)亏损的特征;稀土元素(REE)及其它不活泼元素特征表明蛇绿岩形成于与岛弧无关的环境。变质玄武岩的 Sr 同位素组成受到海水热液蚀变或后期变质作用的影响而有所改变。Nd-Pb 同位素组成特征表明其地幔源区具有典型的印度洋MORB 型同位素组成特征(传统意义上的"Dupal"异常),从而说明其地幔源区属于原特提斯构造域。西秦岭-松潘构造结古洋幔构造归属的研究不仅为研究该构造结内各微陆块构造归属提供重要的约束,也为研究有关陆块间造山带的性质、发展与演化提供了动力学背景。 相似文献
4.
藏南柯月铅锌矿床成矿物质来源:来自硫、铅同位素的证据 总被引：2，自引：2，他引：0
藏南柯月铅锌矿床位于特提斯喜马拉雅构造域Sb-Au-Pb-Zn成矿带东段,矿体主要呈透镜状或脉状,严格受北东向断裂构造所控制,赋矿地层为下侏罗统日当组含碳钙质板岩。矿石硫化物硫同位素δ~(34)S介于9.2‰~11.2‰之间,平均值为9.85‰,与区内日当组地层的δ~(34)S值变化范围相似,表明成矿流体中的硫主要来源于容矿地层。矿石硫化物铅同位素组成为:~(206)Pb/~(204)Pb为19.669~19.813,平均值19.740;~(207)Pb/~(204)Pb为15.823~15.979,平均值15.902;~(208)Pb/~(204)Pb为40.104~40.687,平均值40.410。其结果显示,矿石中的铅具有高放射性成因铅的特征,与喜马拉雅结晶基底的铅同位素组成具有相似的比值,表明矿石铅主要来源于喜马拉雅结晶基底。 相似文献
5.
朱拉扎嘎金矿是近年来在华北地台北缘西段首次找到的以变质沉积岩为主岩的大型金矿床，金矿化主要呈似层状、脉状和透镜体状产在中元古界变质沉积岩地层内，11件硫化物和2件金矿石金岩的δ^34S值变化范围为1.1‰-7.1‰，根据硫化物的产状及形成期次判断，成矿热液中的硫同位素基本上达到了平衡，成矿热液的δ^34S值为2‰左右，暗示硫的来源主要以深源硫为主，与岩浆活动关系密切，6件金矿石中的硫化物、1件变质沉积岩、2件地层火山岩 5件侵入岩体（脉）的^206Pb/^204Pb/^204Pb值分别为17.034-17.725、16.971、17.602-17.513和17.492-17.776,^207Pb/^204Pb为15.297-15.552、15.031、15.436-15.445和15.299-15.564;^208Pb/^204Pb为36.599-37.489、36.347、37.493-37.623和37.606-37.895。在铅构造模式图中，尽管金矿石Pb同位素投影点分布范围较大，但多36.347、37.493-37.623和37.606-37.895。在铅构造模式图中，尽管金矿石Pb同位素投影点分布范围较大，但多数集中于地幔和造山带演化线附近，并与侵入岩铅同位素组成较为接近，反映了铅的来源主要与岩浆活动有关，矿石铅同位素组成可能是侵入岩铅与变质地层中铅混合的结果，S、Pb同位素数据表明，在朱拉扎嘎金矿床，原始地导台的火山岩可能促成了金在地层中的预富集，而海西期大规模的构造-岩浆活动不仅带来了大量的成矿物质，而且使地层中的金活化，并在有利的构造部位沉淀富集，从而形成金矿。 相似文献
6.
北祁连东段红土堡基性火山岩锆石LA -IC P-MS U-Pb年代学及其地质意义 总被引：10，自引：0，他引：10
为精确限定红土堡基性火山岩的形成时代，结合阴极发光分析，分别对北祁连东段红土堡枕状玄武岩和辉绿岩墙进行了LA - ICP - MS 单颗粒锆石微区U - Pb 同位素测年。红土堡枕状玄武岩获得（443.4 ±1.7 ）Ma 和（1 782 ±34 ）Ma 两组年龄值；同时，获得红土堡基性火山岩中辉绿岩墙的年龄为（385.7 ±7.9 ）Ma，并含有（1 697 ±6 ） ～（2 692 ±4 ）Ma 的捕晶锆石年龄信息。认为红土堡基性火山岩的形成时代为晚奥陶世，与其北的陈家河中酸性火山岩的形成时代大体一致，推断红土堡基性火山岩的原始岩浆不同程度遭受了陇山岩群的混染。这一新资料，对进一步研究北祁连造山带东段大地构造格局、构造演化以及北秦岭—北祁连衔接关系具有重要意义。 相似文献
7.
十八倾壕金矿有两种类型矿体：糜棱岩型矿体和石英脉型矿体。糜棱岩型矿石Pb同位素组成以低放射性成因铅为特点：^206Pb／^204Pb为16．63～17．45，^207pb／^304Pb为1531～15．48，^208Pb/^204Pb为36．52～38．85；在铅的动力学演化曲线上非常接近幔源铅演化模式曲线；与区域上典型的韧性剪切带型金矿——后石花金矿的铅同位素组成一致，是早元古代晚期(2040Ma)韧性剪切变质变形作用的产物。石英脉型矿石Pb同位素组成以高放射性成因铅为特点：^206Pb／^204Pb为18.23～19．74，^207Pb／^204Pb为15．69～15．89，^208Pb／^204pb为38．64～40．13；在铅的动力学演化曲线上非常接近上地壳铅演化的模式曲线；与区域上典型的燕山期岩浆热液型金矿——东伙房金矿以及燕山期花岗岩的铅同位素组成一致，是燕山期岩浆热液型金矿化。十八倾壕金矿是两次小同性质成矿作用叠加的结果。这从Pb同位素组成上证明了笔者曾经提出的关于该矿床叠加构造控矿的观点。 相似文献
8.
祁连造山带是原特提斯洋闭合过程中, 阿拉善和柴达木地块在青藏高原东北缘拼合的产物。它是由蛇绿岩残片、海山、岛弧、弧前/弧后盆地等多个构造单元构成的典型增生型造山带, 表现出在多个元古代微陆块周围分布有蛇绿岩和岛弧火山岩的特征。蛇绿混杂带广泛分布于北祁连和南祁连中, 在南祁连主要出露寒武纪玄武岩、安山岩、辉长岩、超基性堆晶岩、硅质岩、灰岩、砂岩和少量地幔橄榄岩, 呈现出蛇绿混杂带的典型特征, 其中拉脊山蛇绿混杂带是该蛇绿混杂带的最大组成部分。因此, 拉脊山蛇绿混杂带的来源和形成构造背景对研究祁连造山带构造演化具有重要的意义。由于构造的复杂性以及系统的野外和岩石学方面研究的缺乏, 拉脊山蛇绿混杂带的岩石组合、同位素年龄和构造背景仍然不清楚, 从而严重制约了区域构造演化的认识。例如, 前人根据灰岩中三叶虫化石将拉脊山地区火山-沉积岩系划归于寒武纪, 然而其它岩石单元的同位素年龄和来源信息相对缺乏, 而且灰岩究竟是本地岩块还是老的异地岩块仍有待进一步研究。岩石地球化学分析结果显示表明寒武纪玄武岩具有MORB、WPB或者OIB的特征, 且部分玄武岩具有岛弧亲缘性。因此, 大陆裂谷、弧后盆地、多阶段抬升构造窗或俯冲-增生杂岩等模式相继被提出。这些分歧严重影响了我们对祁连造山带和原特提斯洋构造演化的认识。究其根本原因, 是由于缺乏将蛇绿岩和岛弧形成视为沟-弧-盆体系演化过程中一个具有成因联系的有机体对其进行综合分析。 相似文献
9.
大陆亚碱性火山岩的成因多样性：以敦化—密山和东宁火山岩带为例 总被引：1，自引：0，他引：1
对东北牡丹江海浪、鸡西鸡林、东宁老黑山三处亚碱性玄武岩类进行了柏A卜”Ar定年和元素与Sr-Nd-Pb同位素组成研究,结果显示,始新世海浪（玄武）安山岩属钙碱性系列,相对富硅碱,贫铁钙,高度富集Rb、Ba、Sr,亏损Th、U、Nb、Ta,富集LREE及极低的HREE含量,与五大连池钾质火山岩相近的同位素组成（^206Pb／^204Pb=16．56～16．66,^207Pb／^204Pb=15．44—15．47,^208Pb／^204Pb=36．80—36．95;ISr=0．704882～0．705564;εNd=-4．05～2．29）,表明来源于较厚的、受交代作用影响的含石榴石富集（LoMu）岩石圈地幔;中中新世鸡林拉斑玄武岩分布极为局限,辉石斑晶发育骸晶结构,富铁、钙、钛,不亏损Nb、Ta,富集Ba、Sr,REE相对平坦,HREE高于OIB,Sr、Nd同位素组成相似于Samoa岛玄武岩,显示源区除软流圈成分外,还有EMII富集组分的加入;晚中新世老黑山拉斑玄武岩,低碱低钾,LREE轻度富集,Nb、Ta不明显亏损,同位素比值与镜泊湖一带中新世碱性玄武岩范围一致,主要来源于软流圈并与富集岩石圈（EMI）发生过相互作用。地幔源区经历了古近纪富集地幔源到中新世软流圈组分增多的演化。东北新生代拉斑玄武岩不同的地球化学特征为认识大陆拉斑玄武岩成因的多样性提供了有益启示。 相似文献
10.
通过对比研究新生代玄武岩Pb,Sr,Nd同位素组成及前寒武纪基底Nd同位素组成,本文将扬子板块东段划归为四个构造－岩石－同位素地球化学省,即苏沪省、嘉山省,北扬子省和南扬子省。其中,喜山省位于庐江－灌云断裂和庐断裂之间,以高^87Sr/^86Sr比（0.70435-0.70490),低^143Ndxx (0.512395-0.512615)和低放射成因铅（^206Pb/^204Pb,^207Pb/^204Pb和^208Pb/^204Pb分别为16.594-17.266,15.317-15.437和37.352-37.782)为特点;苏沪省们于苏皖边界以东,以低^87Sr/^86Sr比（0.70341-0.70392）,高^143Nd/^144Nd比（0.512838-0.513002)和较高放射成因铅（^206Pb/^204Pb,^207Pb/^204Pb^和208Pb/^204Pb分别为17.789-18.275,15.489-15.552和37.831-38.369)为特点;北扬子省位于庐江－灌云断裂以南,富含放射成因铅（^206Pb/^204Pb为18.021-18.150,^207Pb/^204Pb为15.546-15.574,^208Pb/^204Pb为38.154-38.469),而^87Sr/^86Sr比和^143Nd/^144Nd比（分别为0.70464-0.70468和0.512748-0.512774）介于嘉山省和苏沪省之间。 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.
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
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