Late Albian (Early Cretaceous) ammonites from the Provincial Formation of central Cuba     

Ricardo Barragán  Reinaldo Rojas-ConsuegraOttilia Szives 《Cretaceous Research》2011,32(4):447-455

A late Albian ammonite assemblage from the Provincial Formation of Villa Clara Province, Cuba is described. The Provincial Formation is a lithostratigraphic unit of Albian-Cenomanian age extensively exposed in central Cuba and formed within a part of the Caribbean Tethys that was volcanic during the Cretaceous. The formation is mainly composed of calcareous, terrigenous marine, and volcano-sedimentary deposits characterized by a series of micritic limestones intercalated with marls, sandstones, calcareous conglomerates, ash, and tuffaceous material. A rich assemblage of ammonites recovered from the calcareous biomicrites and marls is of late Albian (Stoliczkaia dispar Zone, Mortoniceras rostratum Subzone) age. The ammonite fauna shows a strong Tethyan affinity, and only a single hoplitid ammonite species was recorded. Although scarce, the first Cuban report of this and other boreal ammonite species now allows precise correlations to be made between Cuba and Albian sediments elsewhere in the world.  相似文献   

贵州安顺长兴阶顶部三叶虫化石     

冯凡斌  胡庆  冯庆来 《地层学杂志》2011,(3)

三叶虫是二叠纪末生物集群灭绝中消失的生物门类之一,但是关于该门类生物化石在中国消失的确切层位未见报道。贵州安顺新民剖面大隆组顶部的三叶虫化石Pseudophillipsia sp.产于火山成因的黏土岩之炭质泥岩夹层中,相邻的泥灰岩结核中产牙形石化石Clarkina meishanensis。该黏土岩及炭质泥岩夹层可以与浙江长兴煤山D剖面的第25层对比,这说明三叶虫延续到了主灭绝事件层位,对研究二叠纪末生物集群灭绝的原因具有一定的意义。  相似文献   

Palynological record from a composite core through Late Cretaceous-early Paleocene deposits in the Songliao Basin, Northeast China and its biostratigraphic implications   总被引：1，自引：0，他引：1  

Jianguo Li  David J. Batten  Yiyong Zhang 《Cretaceous Research》2011,32(1):1-12

Two boreholes drilled approximately 75 km apart in the Songliao Basin, Northeast China, have together provided a composite core that represents an almost continuous section through Late Cretaceous-early Paleocene deposits. Eight biozones have been established for this succession of seven formations based on occurrences and associations of biostratigraphically significant palynomorph genera. Seven of these suggest that there was more or less continuous deposition from the late Turonian to the early Paleocene, with the eighth encompassing a Miocene formation that overlies the succession unconformably. This zonation provides a new chronostratigraphic framework for the Late Cretaceous deposits of the Songliao Basin. The ages of most of the formations involved differ from those determined previously. One of the sedimentary units, the Mingshui Formation, includes the Cretaceous/Paleogene boundary, which seems to be indicated by an apparent “mass extinction” of palynomorph taxa, a comparatively rare occurrence outside North America. The upper Quantou Formation, the lowest unit in the succession, is dated as late Turonian-Coniacian, which is much younger than previously thought. The same applies to the overlying Qingshankou and Yaojia formations, and also to the other three (Nenjiang, Sifangtai and Mingshui) but to a lesser extent, in the conformable succession. The Early/Late Cretaceous boundary must now be located probably below the Quantou Formation, either between it and the underlying Denglouku Formation or within the latter.  相似文献   

晚三叠世龙门山前陆盆地早期(卡尼期)碳酸盐缓坡和海绵礁的淹没过程与动力机制   总被引：2，自引：2，他引：0  

李勇  苏德辰  董顺利  孙玮  杨荣军  刘树根  颜照坤  闫亮 《岩石学报》2011,27(11):3460-3470

晚三叠世龙门山前陆盆地分布于扬子克拉通西缘,属于印支期造山楔构造负载驱动的挠曲型前渊凹陷.其中卡尼期马鞍塘组是分布于底部不整合面之上的第一套地层单元,记录了前缘隆起边缘碳酸盐缓坡和海绵礁的构建和淹没过程.据钻孔揭示马鞍塘组的最大厚度超过250m,显示为西北厚东南薄的楔形结构,从北西向南东依次分布了深水盆地、碳酸盐缓坡和海绵礁和浅水滨岸带等沉积物类型.其中碳酸盐缓坡和海绵礁分布于前陆盆地的远端,呈面向西的条带状展布,其走向线与龙门山冲断带的走向大致平行.碳酸盐缓坡和海绵礁的厚度介于30～100m之间,由北西向南东变薄.在垂向上,马鞍塘组由3部分构成,下部为鲕粒滩和生物碎屑滩,中部为海绵礁,上部为黑色页岩,显示为向上变细、变深的沉积序列.在Li et al.(2003)盆地模拟的基础上,本次对卡尼期前陆盆地的沉降速率、沉积速率、海绵礁生长速率、相对海平面上升速率进行了定量计算,其中沉降速率为0.10mm·a-1、沉积速率为0.04mm·a-1、海绵礁生长速率为0.03mm·a-1、相对海平面上升速率介于0.01mm·a-1～0.05mm · a-1之间.研究结果表明:在卡尼期早期,相对海平面处于初始上升阶段,相对海平面上升速率较小,盆地处于欠补偿状态,沉积了碳酸盐缓坡型鲕粒滩和生物碎屑滩;在卡尼期中期,相对海平面上升速率等于海绵礁生长速率,海绵礁持续保持垂直向上的生长状态,形成了高度达100余米的塔礁;在卡尼期晚期,相对海平面上升速率大于海绵礁生长速率,礁顶的水深逐步变大,导致礁体被淹溺致死,从而在卡尼期形成了鲕粒灰岩滩-生物碎屑滩-海绵礁灰岩-页岩的向上变细、变深的沉积序列,显示了前陆盆地早期碳酸盐缓坡和海绵礁生长并被淹没的特有模式.本次研究成果表明龙门山前陆盆地的底部不整合面和碳酸盐缓坡、海绵礁的淹没过程是扬子板块西缘印支期造山楔逆冲构造负载的挠曲变形的产物,显示了在卡尼期松潘-甘孜残留洋盆的迅速闭合和造山楔构造负载向扬子板块的推进过程.  相似文献   

哀牢山构造岩浆带晚二叠世-早三叠世火山岩特征及其构造环境   总被引：15，自引：7，他引：8  

刘翠  邓晋福  刘俊来  石耀霖 《岩石学报》2011,27(12):3590-3602

本文对中国云南哀牢山构造岩浆带内的雅轩桥、帽盒山、绿春火山岩等开展了相关研究.雅轩桥附近的火山岩为晚二叠世,岩性主要为橄榄粗安岩-玄武岩(少量安山岩),在TAS图上既有碱性又有亚碱性.钾含量较低(＜1.19％),为低钾钙碱-中钾钙碱性,Peacock碱钙指数以钙碱性为主.与MORB相比,其痕量元素蛛网图亏损Nb、Ta,而富集Pb,从Zr-V曲线呈平坦型,并且整体比MORB亏损.稀土元素配分模式与MORB相近,但略显轻稀土元素富集和重稀土元素亏损.在构造环境判别图上均位于火山弧环境.他郎河边(雅轩桥地区)火山岩为英安岩,属亚碱性,中钾钙碱性,Peacock指数为钙性.痕量元素蛛网图、REE模式图以及大地构造环境判别图,均表明其属于弧的构造环境.由上推测雅轩桥火山岩在晚二叠世属于弧火山岩.帽盒山玄武岩的锆石SHRIMP U-Pb测年结果为249±1.6Ma,为早三叠世.岩性为亚碱性钠长玄武岩,低钾钙碱性系列,Peacock碱钙指数以钙性为主.痕量元素蛛网图和REE配分模式图与MORB相比,LREE略微富集.在构造环境判别图中位于从E-MORB向岛弧过渡的构造环境.绿春地区流纹岩的锆石SHRIMP U-Pb年龄为247.3±1.8Ma,为早三叠世,属亚碱性,钾玄岩系列,Peacock碱钙指数为碱钙性.痕量元素蛛网图、REE配分模式图及大地构造环境判别图显示其为成熟岛弧向陆陆碰撞的过渡环境.结合前人研究,推测哀牢山洋在晚泥盆世形成,可能在石炭世-早二叠世(?)处于洋的扩张期.晚二叠世时,在哀牢山洋的西侧出现了雅轩桥的初始孤火山岩,预示着至少在这一时期,哀牢山洋已经开始俯冲.到三叠世早期(249±1.6Ma),在哀牢山洋的东侧出现了具有弧和MORB的双重特性的帽盒山玄武岩,可能指示此时哀牢山洋盆已经变小,或已转化为孤间或弧后盆地,洋的演化进入了晚期阶段,并且在局部地段,如绿春地区,此时(247.3±1.8Ma)已经进入到成熟岛弧向陆陆碰撞的过渡阶段.因此支持哀牢山洋在晚三叠世闭合的结论,亦符合上三叠统一碗水组不整合在哀牢山蛇绿混杂岩之上的事实.  相似文献   

东坑-菖蒲地区燕山晚期脉岩地球化学特征及其成因     

胡志华  林锦荣  郭树英  钟启龙  庞雅庆  戎嘉树  高飞 《铀矿地质》2011,27(4):206-214

本文以东坑-菖蒲地区发育的燕山晚期脉岩为对象,阐述了其岩石学和地球化学特征,并结合脉岩产出的大地构造背景,对其成因进行探讨。认为中基性脉岩为岩浆快速上升侵位所形成,其岩浆来源于地幔混染端员,源区受到富集地幔流体的交代作用;酸性脉岩具A2型花岗岩特征,岩浆源区较深,以地壳组分为主,受到富集地幔组分混染;推测该区部分铀成矿流体和成矿物质来源于地幔或下地壳。  相似文献   

浙西开化地区桐村花岗斑岩LA-ICP-MS锆石U-Pb年龄及其地质意义     

邱骏挺  余心起  张德会  代堰培  李弘珂  陈帅奇 《中国区域地质》2011,(9):1360-1368

报道了浙西开化地区桐村含Cu、Mo花岗斑岩的LA-ICP-MS锆石U-Pb年龄,2个样品加权平均年龄介于167.6～155.6Ma之间,反映花岗斑岩形成于中、晚侏罗世。该时期同时又是燕山运动活跃的时期,区域构造以北西—南东向挤压为特征,形成走向北东的压性断裂和配套的南东向张性断裂。2组断裂交会产生的应力薄弱区为燕山期发生的规模性岩浆活动提供了侵位通道。因此,浙西地区拥有良好的构造和岩浆成矿条件,成矿潜力巨大。  相似文献   

Systematics, Behavior and Living Environment of Shantungosaurus Giganteus (Dinosauria: Hadrosauridae)     

JI Yannan  an  WANG Xuri  LIU Yongqing  JI Qiang 《《地质学报》英文版》2011,85(1):58-65

On the basis of the taphonomy, osteological anatomy and ontogenetic variation, Zhuchengosaurus maximus Zhao et al., 2007 is considered to be synonymic with Shantungosaurus giganteus Hu, 1973 herein. This paper also deals with the life behavior of S. giganteus and the environment in which S. giganteus lived. S. giganteus is considered to be a terrestrial and gregarious herbivorous dinosaur and lived in hills and intervales in warm weather with plentiful rain and flourishing vegetation.  相似文献   

新疆西准噶尔晚古生代大地构造演化的岩浆活动记录   总被引：13，自引：2，他引：11  

尹继元  袁超  王毓婧  龙晓平  关义立 《大地构造与成矿学》2011,35(2):278-291

晚石炭世-早二叠世是新疆北部最为重要的金属矿床成矿期.西准噶尔的区域大地构造、蛇绿岩、沉积岩、花岗岩、埃达克岩、富镁闪长岩以及广泛出露的中基性岩墙研究显示,该地区直到早二叠世早期(290Ma)仍有残余洋盆存在,并可能存在相关的俯冲活动.在290Ma之后,伴随着红色磨拉石的产出,西准噶尔地区进入碰撞造山阶段,伴有地壳快速...  相似文献   

阴山-燕山地区晚侏罗世-早白垩世土城子组地层、沉积特征及盆地构造属性分析   总被引：3，自引：0，他引：3       下载免费PDF全文

许欢  柳永清  刘燕学  旷红伟 《地学前缘》2011,18(4):88-106

阴山-燕山地区广泛分布晚侏罗世-早白垩世土城子组,保存了土城子组形成时期的古气候、古地理及大地构造演化的重要信息.然而,对于土城子组的沉积特征、盆地属性和大地构造背景仍存很大争议.文中对前人关于土城子组的相关研究成果进行了总结,在依据实测资料的基础上,以盆地分析方法为手段,从地层、沉积相、物源和古水流入手,研究和分析了...  相似文献