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形成于印支期的大别造山带和周缘中生代盆地构成了一级源汇系统,其中位于造山带北缘的合肥盆地中生代地层发育,且以盆地南缘出露最好,这为盆山源汇系统研究提供了理想的沉积记录。笔者从合肥盆地南缘采集了10个砂岩样品和1个砾岩样品,进行锆石U/Pb (LA-ICP-MS)定年分析,获得了742个有效年龄(置信度不小于85%),范围为113±3. 6-2983 Ma。这些碎屑锆石年龄谱可以被分为5个年龄段:113-137 Ma,峰值131 Ma; 184-273 Ma,峰值226 Ma; 274-517. 3 Ma,具有2个峰值280 Ma和474 Ma; 532-856. 6 Ma,具有3个峰值572 Ma、649 Ma和772 Ma; 1786-2600 Ma,具有2个峰值2035 Ma和2506 Ma。同时,总结了物源区大别造山带不同单元锆石U-Pb年龄特征。根据锆石U/Pb年龄和Th/U值,发现这5个年龄段比较准确地记录了物源区地质体,分别是早白垩世的岩浆岩、大别山高压—超高压变质岩、北淮阳的浅变质岩、北大别的正片麻岩和卢镇关群变质岩。根据锆石最小年龄,修正了合肥盆地南缘中生代地层格架,为源汇系统研究确立了时间框架。合肥盆地南缘中生代沉积可以分为4个演化阶段:晚三叠世瑞替期—早侏罗世辛涅缪斯期、中—晚侏罗世、早白垩世早期和早白垩世晚期,并据此确定了每个阶段主要物源区特征及其时空变化。碎屑锆石U/Pb年龄和Th/U值限定了大别造山带仅存在三叠纪的超高压变质作用,且超高压变质岩折返到地表的最早时间是晚三叠世瑞替期,大别造山带大陆岛弧发育的时间是新元古代。上述研究结果不仅为恢复大别造山带构造古地理做出了新的贡献,而且更为盆山源汇系统研究提供了一个实例。 相似文献
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大别山及邻区侏罗和石炭纪时期盆-山耦合：来自沉积记录的认识 总被引：5，自引：1，他引：5
侏罗纪时期大别造山带是合肥盆地的物源区。因此通过盆地中的沉积记录可以了解该造山带的地质演化,并重建造山带的古地理面貌。在合肥盆地最古老的中生代地层中(防虎山组,J_1),底部的沉积物源区主要为华北陆块早古生代和吕梁期(1700～1900Ma)的岩石。但是,从防虎山组沉积早-中期开始直至晚侏罗世,来自俯冲的扬子陆块折返的物质则构成为大别山的主体。防虎山组地层含高 Si 含量的碎屑多硅白云母和三叠纪年龄的锆石,三叠纪年龄的锆石含超高压(UHP)矿物包裹体,证明扬子大陆深俯冲(至地幔)的物质在早侏罗世时期已出露至大别山地表。高压-超高压的变质岩广泛分布於中-晚侏罗世时期东-中部的大别山,但向西逐渐消失。大别山北缘石炭系沉积岩的微量元素组成特征强烈指示它们应来源於一个被剥蚀的大陆岛弧。其碎屑锆石年龄结构主要由具有秦岭和二郎坪群特征(400～480Ma)的岩石组成、因此,大别山北缘石炭纪沉积主要来源于华北大陆南缘相当於秦岭和二郎坪群的岩石,物源区在早古生代时期曾经历过与秦岭造山带相似的岛弧构造环境的演化。大别山北缘晚石炭世沉积物中高 Si 含量碎屑多硅白云母的发现指示其沉积物源区可能出露有高压-超高压的变质岩。 相似文献
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以鲁西淄博、临朐、平邑、蒙阴盆地为重点研究区,通过盆地中生界砂岩中碎屑石榴石的成分分析,探讨鲁西隆起及周边地区中生代构造演化历史。研究表明,鲁西盆地砂岩中石榴石成分在早中侏罗世和中晚侏罗世期间出现变化,暗示着物源的转变,早中侏罗世时期主要物源是鲁西隆起,中晚侏罗世时期转变为胶东地区和鲁西隆起。侏罗纪时期石榴石的物源转变显示,苏鲁苏鲁造山带可能在中晚侏罗世时期已经抬升至地表。白垩纪鲁西盆地物源主要为胶东地区,鲁西隆起的物源贡献较小,但是青山组中段和王氏组中段物源略有波动。白垩纪鲁西盆地石榴石物源显示,控制鲁西盆地沉积的主要是苏鲁造山带,古地理格架显示东高西低的特征,盆地物源的波动暗示鲁西隆起可能在早白垩世中晚期和晚白垩世中期经历过抬升。 相似文献
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大别高压—超高压变质岩剥露历史在合肥盆地的记录 总被引：5，自引：1，他引：4
位于大别造山带北部的合肥盆地,其中的沉积是造山带剥露历史的重要记录。自生伊利石K—Ar测年,证实了合肥盆地中部安参1井自上而下钻遇了下白垩统,上、中、下侏罗统,下二叠统和上石炭统地层,下伏为奥陶系。中生界砂岩碎屑组分分析,表明其源区为大别造山带。安参1井内下二叠统砂岩不含造山带来源的碎屑多硅白云母。自下侏罗统至下白垩统,钻遇的砂岩中连续出现了丰富的碎屑多硅白云母(Si>3．3)。这不但指示大别造山带是合肥盆地的主要物源区,也限定了大别高压—超高压变质岩在早侏罗世早期就已经剥露地表．继而连续出露。 相似文献
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通过同构造沉积物质记录了解物源区剥蚀作用过程进而探索盆山构造相互关系,是大陆构造动力学研究的一个重要方面。砂岩骨架成分分析和重矿物及部分标型矿物分析方法,已被较多地用来探索新疆天山造山带与其南部库车盆地晚中生代以来的相互关系和构造演变过程,但是关于中生代较早时期库车盆地构造属性及北部造山带隆升剥蚀过程的认识仍存在较大分歧。本文运用电子探针微区成分分析方法,对库车盆地北缘中段晚三叠世和早侏罗世砂岩中具代表性的15个砂岩样品中的38颗碎屑长石和26颗碎屑白云母矿物进行了矿物化学成分分析。结果表明,长石主要来自变质岩物源区,25颗碎屑白云母均属多硅白云母,表明其源区岩石曾经历了高压变质作用。这些多硅白云母中Si原子含量显示它们比目前保留在天山造山带高压变质带蓝片岩和榴辉岩中的多硅白云母形成的压力要低,可能反映了源区高压变质岩的正常剥露顺序。这项研究结果表明,至少在晚三叠世-早侏罗世时期,库车盆地北部天山造山带中的高压变质岩已经剥露于地表并遭受剥蚀成为物源供给区。具体是中天山南缘早古生代高压变质带还是晚古生代南天山高压变质带作为重要物源区,尚需进一步的研究工作。 相似文献
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秦岭造山带印支期造山作用控制着济源盆地的形成与演化,对盆地中沉积物物源进行研究,有利于恢复造山带造山-隆升的细节.通过对济源盆地中生代泥岩地球化学的系统分析,发现样品的CIA(化学风化指数)校正值在早-中三叠世、晚三叠世、早-中侏罗世和中侏罗世后期的平均值分别为68.5、76.4、86.0和73.7,这一演化特征可能反映其经历了古气候控制的化学风化过程.但是三叠纪样品CIA值明显过低,可能与源区活动的构造背景相关;ICV(成分变异指数)值显示沉积物具有初次沉积的特征,反映了源区早期发生过弧-陆碰撞或具备陆缘弧特征的克拉通基底隆升.而早-中侏罗世样品表现为高的CIA值,ICV值显示沉积物具有再循环特征,其初次沉积可能发生在弧后盆地中,后随造山带的隆升,被剥露再搬运而沉积下来.泥岩物源区构造环境判别结果显示,沉积物主要来自活动大陆边缘和被动大陆边缘,且含有较多大陆岛弧(陆缘弧)的信息.由此说明,中生代济源盆地盆缘构造活动经历了由克拉通基底隆升到造山带剥露的过程,这一过程与秦岭造山带印支期的造山作用密切相关. 相似文献
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大别山北缘中生界的沉积学研究表明,三尖铺组向上变细的巨旋回记录了从河川径流到碎屑流、超浓缩洪流到远端河道以及越岸沉积,显示源区在早侏罗世(205～180Ma)之前快速抬升之后经历了相对平静阶段.凤凰台组向上变粗的扇砾岩巨层序记录了碎屑流-超浓缩洪流沉积,反映了在侏罗纪末(135Ma)到早白垩世源区剧烈的持续上升和剥蚀,导致向盆地远端砾岩的进积作用.早白垩世晚期,黑石渡组巨旋回下部的碎屑流沉积是近源堆积,上部发育湖相浊积岩,反映源区的构造演变为转换拉张.晚白垩世,盆地边缘与源区一道抬升,遭受剥蚀. 相似文献
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本文在对渭河地区及周缘晚古生代-中生代残存地层分布研究的基础上,采用岩石学、锆石同位素年代学、主微量元素地球化学分析方法,对渭河地区南北两侧上古生界二叠系及中生界三叠系进行对比,进而恢复了研究区晚古生代晚期、中生代早期沉积面貌,并结合裂变径迹构造抬升的研究结果,探讨了渭河地区中生代后期改造过程及演化阶段。结果显示:渭河盆地内部主要凹陷可能仅残留小范围的、不连续的C-P地层,未发现中生代地层。岩石学、锆石U-Pb年龄、主微量元素表明鄂尔多斯南部和北秦岭地区二叠系、三叠系具有很好的对比性,两者在相同时期为同一盆地。二叠系碎屑岩源区可能为再旋回造山带及陆块源区,主要来自北秦岭中-新元古界宽坪群变质碎屑岩及南部二郎坪群火山-沉积岩;三叠系沉积岩物源主要来自北秦岭地区的宽坪群、秦岭群或同期发育的火山岩。裂变径迹资料暗示渭河地区与渭北隆起及秦岭造山带中生代抬升期次具有一致性:晚侏罗世-早白垩世末,地层以强烈的构造变形、弱抬升为主;早白垩世末以来,地层发生大规模抬升、剥蚀,致使上古生界-中生界在渭河地区残留较少。在以上研究的基础上,将渭河地区晚古生代-中生代演化过程分为晚古生代二叠纪、中生代三叠纪-早中侏罗世、晚侏罗世-早白垩世末、早白垩世末-白垩纪末几个演化阶段。 相似文献
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刘宝珺 余光明 徐强 G. Einsele W. Frisch 刘光华 J. Wendt A. Wetzel L. Ratschbacher H. P. Luterbacher 《沉积与特提斯地质》1993,(1):32-49
通过对喜马拉雅三叠纪到第三纪区域沉积特征分析,阐明了雅鲁藏布喜马拉雅特提斯造山带从裂谷—被动大陆边缘—前陆盆地的沉积盆地演化史。随着以雅鲁藏布带为代表的喜马拉雅特提斯打开,三叠纪到早侏罗世为特提斯早期裂开的大陆边缘裂谷盆地。早期裂谷中心部位不是现在大陆缝合线的雅鲁藏布一带,而在低分水岭带。晚侏罗世到早白垩世,雅鲁藏布江南测为典型被动大陆边缘,其沉积盆地沉降、海平面变化与沉积作用相吻合。晚白垩世到第三纪为前陆盆地演化阶段,从沉积作用可以识别出晚白垩世晚期为造山第一暮,第三纪初为第二幕。 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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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.) 相似文献
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正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology, 相似文献
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正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.) 相似文献
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正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se- 相似文献
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正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with 相似文献