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华北南缘陆坡带奥陶纪冰海砾岩的发现及意义 总被引：1，自引：0，他引：1
中奥陶纪末伽马射线暴击中地球引发气候变冷的天文地质事件,形成广布全球的冰期沉积,华北板块却未见遗存。通过在豫西栾川-卢氏地区新一轮1∶5万区域地质调查(2016～2018年),在原划归三岔口组砾岩中厘定出一套冰海成因砾岩,结合区域同位素数据,以及遗存生物化石和野外层位关系,推断该套冰海成因砾岩是这次天文地质事件在华北南缘陆坡带的地质记录。新一轮1∶5万区域地质调查在侵入冰海砾岩层中的正长斑岩脉岩获取(434±23)MaU-Pb同位素年龄,佐证了华北南缘陆坡带发育的这套冰海沉积砾岩形成时代大致相于晚奥陶纪世赫南特期[(443.4±1.5)Ma～(445.2±1.4)Ma]。该套冰海成因砾岩的发现填补了奥陶纪末大冰期在华北板块的空白。 相似文献
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鄂尔多斯(地块)盆地南缘唐王陵砾岩的沉积时代长期存在晚前寒武纪(或震旦纪)与奥陶纪之争,沉积环境和物源组成也存在不同认识,是盆地南缘海相沉积地层及构造古地理研究关注的热点争议问题。本文采用碎屑锆石U-Pb年代学和岩石地球化学研究方法,综合分析探讨了唐王陵砾岩的沉积时代、物源组成及其构造古地理环境。结果表明:唐王陵砾岩自下而上三个组段的砂岩夹层样品、共计396颗碎屑锆石U-Pb谐和年龄数据主要分布在2531～2364Ma(n=25)、2120～1618Ma(n=268)、1230～940Ma(n=29)和905～744Ma(n=10)等四个年龄区间,相应的峰值年龄分别为2440Ma、1800Ma、1090Ma和810Ma,各组段样品单颗粒锆石最小年龄为829±11Ma、820±17Ma和744±8Ma。这一测年结果与盆地西南缘的震旦系正目观组和罗圈组碎屑锆石U-Pb年龄分布基本相似,但明显缺少其近邻剖面奥陶系平凉组碎屑锆石接近454Ma的高频年龄组分,表明唐王陵砾岩的沉积时代更接近新元古代晚期或震旦纪。碎屑锆石年龄谱物源示踪与岩石地球化学、沉积建造特征等综合分析结果揭示,唐王陵砾岩沉积具有来自(华北)鄂尔多斯陆块与祁连-北秦岭(杂岩)地体的双向混合物源特征,总体属于含有多套滑塌和水下扇堆积的滨浅海相碳酸盐岩和碎屑岩沉积建造组合体,主体形成于鄂尔多斯地块南缘新元古代晚期的被动大陆边缘伸展断陷海盆环境。唐王陵砾岩碎屑锆石测年数据接近1. 09Ga和0. 81Ga的年轻峰值年龄组分,提供并支持祁连-北秦岭地区存在格林威尔期Rodinia大陆聚合-裂解相关的构造岩浆活动事件,指示(华北)鄂尔多斯陆块与北秦岭地体至少在唐王陵砾岩沉积之前的格林威尔期曾经历过拼贴聚合-陆缘增生作用;随后受Rodinia大陆裂解事件的影响,鄂尔多斯地块南缘拼贴增生型大陆边缘发育形成了包括唐王陵砾岩在内的新元古代晚期陆缘滨浅海滑塌-碎屑流沉积。 相似文献
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西湖凹陷是东海陆架盆地重要的富生烃凹陷之一，平湖组是主要烃源岩和油气富集层系。为了探讨平湖组沉积期构造背景、源区性质及古环境，本文对平湖组泥质岩地球化学特征进行了研究。地球化学分析结果表明，平湖组沉积期同时具有大陆岛弧和活动大陆边缘构造背景。平湖组泥质岩的物源区母岩主要由上地壳岩石演化而来，并通过对比周围隆起区母岩特征，认为西侧的海礁隆起为西湖凹陷西部斜坡区平湖组沉积期的主要物源区，母岩主要以上地壳的长英质火成岩为主，并受到少量来自幔源岩浆和上地壳古生界变质岩系的影响，母岩类型主要为花岗闪长岩和英安质凝灰岩，少量安山岩和变质岩。泥质岩CIA分析表明，平湖组泥质岩的母岩经历了中等—强烈的风化作用，结合Sr/Cu值分析，推断西湖凹陷在平湖组沉积期古气候较为温暖湿润。微量元素和古盐度分析结果以及对盆地古地貌特征分析表明，西湖凹陷平湖组沉积期自北向南沉积背景有明显的地区差异性，北部（A- 1）沉积水体为淡水，主要发育河控三角洲沉积体系，而中部（A- 2）和南部（B- 1）表现为淡水和半咸水交替演化的特征，主要发育受潮汐影响三角洲沉积体系。平湖组泥质岩主要形成于含氧环境中。 相似文献
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华北地块北缘中新元古界沉积构造演化 总被引：2，自引：0，他引：2
根据文献资料及对研究区8 条实测剖面资料的综合分析结果表明,Columbia 超级大陆的裂解导致华北陆块北缘大陆裂
谷盆地的形成。随着大陆进一步伸展和洋壳的形成,华北地块北缘逐渐发展为被动大陆边缘。在1400 Ma 左右,即铁岭组
沉积后,华北地块北缘转变为活动大陆边缘。早期洋壳向华北地块低角度的俯冲造成弧后地区发生挤压（芹峪上升）,导致
铁岭组抬升和剥蚀,而后期洋壳高角度的俯冲又造成弧后区域发生强烈的伸展和断陷,沉积了下马岭组,并伴随辉绿岩的
侵入。华北地块与相邻地体之间的碰撞导致下马岭组的抬升（或蔚县抬升）以及碰撞花岗岩的形成,挤压构造发生的时间
对应于Rodinia 超级大陆的形成期。新元古代沉积是Rodinia 超级大陆裂解的结果。龙山组石英砂岩和海绿石砂岩是Rodinia
超级大陆裂解后的最早期沉积,记录了海侵初期的超覆过程。 相似文献
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鄂尔多斯盆地碳酸盐岩是当前的油气勘探热点。当前对鄂尔多斯盆地不同构造区的潜在碳酸盐岩储层及圈闭仍认识不清，阻碍了勘探目标优选。本文通过构造-沉积分异特征分析，揭示了鄂尔多斯盆地早古生代碳酸盐岩台地的构造-沉积分异演化过程及其后期构造改造分异特征。结果表明，受中央古隆起和陆表海环境的控制，盆地南缘以发育镶边礁滩相储层为特征，西缘以发育层状弱镶边礁滩储层为特征，内克拉通则以局限的台地潮坪白云岩储层为特征；三个不同构造-沉积分异区的碳酸盐岩建造都具备成藏条件，但遭受的构造形变具有显著差异，可分为西缘压性构造区、南缘张性构造区和内克拉通稳定构造区；西缘陆内前陆盆地的破碎褶皱带的有利圈闭包括逆掩断层遮挡圈闭和向斜中的次级背斜圈闭；南缘受渭北地堑影响形成的张性构造带发育基底潜山相关圈闭；内克拉通的伊陕斜坡带为一长期保持构造稳定的弱改造的大型单斜构造，以发育岩性圈闭型为特征，岩性圈闭的沉积相分布主要受陆表海旋转潮汐流的约束。 相似文献
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鄂尔多斯盆地下奥陶统马家沟组马六段在盆地南缘广泛分布,从北向南厚度增大。岩性为含藻石灰岩、云斑灰岩、粉晶白云岩和颗粒白云岩。从早奥陶世华北地台南缘大地构造背景出发,分析了鄂尔多斯盆地南缘下奥陶统马家沟组马六段的沉积环境和沉积模式。综合露头剖面与井下岩心分析资料及岩性组合特征,探讨了马六段成藏要素及其空间配置关系,指出马六段以局限洼地和白云质石灰岩台坪沉积为主,局部层段发育礁滩相沉积,经后期成岩白云岩化可形成有效的白云岩储层,与上覆富含泥质的平凉组共同形成上生下储型成藏组合,具有一定的资源潜力。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
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
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
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
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
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
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Emmanuel Skourtsos Daniel Vachard Alexandra Zambetakis-Lekkas Rossana Martini Louisette Zaninetti 《Comptes Rendus Geoscience》2002,334(12):925-931
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
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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
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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
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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
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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
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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
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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