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1.
论江西双桥山群的底界问题   总被引:5,自引:0,他引:5  
1:5万庐山地区区域地质调查和专题研究,在星子县黄岭一带发现一套巨厚层状复成分的变质砾岩,根据该变质砾岩的砾石成分,变形组构及区域分布特点,以及上部(双桥山群)与下部(星子岩群)地层在变质方面存在明显差别,认为变质砾岩应属于双桥山群的底部层位,是中古元办双桥山群与下伏下元古界星子央群不整合关系的佐证,由于受后期构造叠加改造的影响,现今二者呈断层或隐蔽不整合接触关系。  相似文献   

2.
1∶5万庐山地区区域地质调查和专题研究,在星子县黄岭一带发现一套巨厚层状复成分的变质砾岩。根据该变质砾岩的砾石成分、变形组构及区域分布特点,以及上部(双桥山群)与下部(星子岩群)地层在变质与变形方面存在明显差别,认为变质砾岩应属于双桥山群的底部层位,是中元古界双桥山群与下伏下元古界星子岩群不整合关系的佐证。由于受后期构造叠加改造的影响,现今二者呈断层或隐蔽不整合接触关系。  相似文献   

3.
安徽省境内有宿松群与大别群接触关系性质的厘定   总被引:3,自引:0,他引:3  
侯明金  汤加富 《现代地质》1998,12(4):541-547
运用构造地层学的理论和方法,详细解剖了安徽省境内宿松群与大别群在几个重要地段接触关系的性质,提出宿松群南西部的大别群主要是变形变质侵入体,与宿松群为先侵入,后构造的接触关系。在宿松群大新组厚层白云质大理岩之上发现多层透镜状层间砂砾岩层,沉积和构造标志均显示其层位在大新屋组之上,对原来认为的不整合接触关系和底砾岩提出质疑。  相似文献   

4.
位于华北克拉通中部造山带内部的五台杂岩与毗邻的阜平、恒山杂岩是最经典的前寒武纪地质研究地区。被认为该地区最年轻的地质单元滹沱群不整合覆盖于五台和阜平杂岩之上。近来的工作越来越显示出滹沱群对于该地区乃至整个中部造山带的构造演化的重要性。然而对滹沱群沉积岩物源的缺乏认识阻碍了对该区沉积环境和构造意义的进一步研究。本文利用LA-ICP-MS,从滹沱群最底部的花岗质砾岩中获取了U-Pb锆石年龄,结合前人的地层学、地质年代学、构造地质学以及变质作用研究,对该地区底砾岩的沉积物源及大地构造演化提供了新的制约。滹沱群自下而上由底砾岩和火山碎屑岩(豆村亚群)、碎屑岩、板岩、白云岩和大理岩(东冶亚群)以及砂岩和另外一套出露于顶部的砾岩(郭家寨亚群)组成。来自于滹沱群底砾岩的花岗质砾石中的锆石获得了2517~2566Ma的207Pb/206Pb权重年龄,与五台新太古代的花岗岩(2566~2515Ma)年龄一致,说明这些花岗质砾石来源于五台新太古代花岗岩。结合前人的研究,滹沱群很有可能代表了一个发育在西部陆块向东部陆块俯冲过程中与俯冲相关的弧后前陆盆地。该盆地在约1850Ma华北克拉通最终碰撞拼合事件过程中闭合。滹沱群花岗质砾岩的...  相似文献   

5.
在豫西东秦岭造山带核部秦岭群变质杂岩西缘,措朱夏断裂和商丹断裂广泛分布着一套“含砾大理岩”,自50年代发现以来,先后提出海相冰碛岩、沉积砾岩、滑塌堆积、构造假砾及构造混杂岩等多种成因假说。近据宏、微观构造研究,认为应是含砾碳酸盐质糜棱岩,由变形强烈的多成分砾石与复杂揉皱状条纹(带)大理岩基质组成。其内砾石是属高级变质大理岩中硅质、长英质及白云质大理岩的变质条带,  相似文献   

6.
五台山西段的"探马石"砾岩,原被确认为系甘泉不整合西延部份的底砾岩.经研究认为"探马石"砾岩不是底砾岩,而是构造形成的棒石糜棱岩.  相似文献   

7.
摘 要  运用构造地层学的理论和方法‚详细解剖了安徽省境内宿松群与大别群在几个重要地 段(猪婆寨、梓树坞、杨岩、大新屋和柳坪)接触关系的性质‚提出宿松群南西部的大别群主 要是变形变质侵入体‚与宿松群为先侵入、后构造的接触关系。在宿松群大新屋组厚层白云 质大理岩之上发现多层透镜状层间砂砾岩层‚沉积和构造标志均显示其层位在大新屋组之上 (新建为梓树坞组)‚对原来认为的不整合接触关系和底砾岩提出质疑。  相似文献   

8.
提要:通过对龙门山构造带中段玉堂镇新近系砾岩层的砾组分析,阐述了砾岩层的成因、来源、搬运方式和构造背景等。研究表明,玉堂镇新近系砾岩层为近—中源河流相冲积物,物源为来自北西方向龙门山构造带中的基岩地层,砾石成分复杂,底部砾岩层的砾石成分以盖层沉积岩和浅变质岩为主,中部砾岩层中基底花岗岩砾石成分则大幅度增加,水动力条件不稳定,砾石原始最大扁平面倾向具有向NW转变的趋势。反映龙门山地区新近纪地壳运动渐趋强烈,且古构造应力场方向发生过由NWW向NW向的转变。  相似文献   

9.
苏鲁高压-超高压变质地体南缘高压与超高压变质带接触关系的确定对该地区构造格局的建立具有重要的意义。研究表明苏鲁高压-超高压变质地体南缘高压变质带内的锦屏群底部含砾岩层不整合覆盖于超高压变质带南部的朐山花岗片麻岩之上,含砾岩层中的砾石虽然经历了后期的塑性变形改造,但其地质特征仍展示出地层下部层位沉积砾石特有的性质。此外,同位素年代学研究揭示出朐山花岗片麻岩与锦屏群变质岩的原岩分别形成于859Ma和814Ma。这些都说明锦屏群变质岩与下伏朐山花岗片麻岩原岩之间的接触关系为角度不整合。在后期的构造运动过程中它们一起经历了高压-超高压变质变形作用,折返过程中锦屏群变质岩向北西西方向逆冲,形成叠加于不整合接触面的韧性剪切带。  相似文献   

10.
鲁西地区泰山岩群雁翎关组为华北克拉通新太古代典型花岗绿岩带的重要组成部分,形成时代大于2.6Ga.对其中变质砾岩中的一花岗质砾石进行了锆石SHRIMP定年,(2632±18)Ma年龄为砾石所代表的花岗质岩石的形成时代,表明雁翎关变质砾岩中至少部分砾石为构造成因.该砾石可解释为花岗岩脉经构造变形而形成.结合前人研究成果,对泰山岩群形成时代和绿岩带基底岩石特征进行了探讨.  相似文献   

11.
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.  相似文献   

12.
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.  相似文献   

13.
Robert L. Linnen   《Lithos》2005,80(1-4):267-280
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.  相似文献   

14.
Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931.  相似文献   

15.
PALEONTOLOGY     
正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.)  相似文献   

16.
正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.)  相似文献   

17.
正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.)  相似文献   

18.
PETROLOGY     
正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus.,  相似文献   

19.
正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an  相似文献   

20.
正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of  相似文献   

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