The Most Complete Sequence of Telychian Graptolite Zones in the World   总被引：1，自引：0，他引：1  

FU Lipu  ZHANG ZifuXi ''an Institute of Geology  Mineral Resources  Xi ''an  Shaanxiand GENG LiangyuNanjing Institute of Geology  Palaeontology  Chinese Academy of Sciences  Nanjing  Jiangsu 《《地质学报》英文版》2000,74(2):126-131

This paper divides the Telychian into 7 graptolite zones, 12 subzones and 4 chitinoans in the Ziyangregion, China. The zones and subzones of England are almost totally suitable for the case of Ziyang in China, though they are 10000 km apart. All the above-mentioned biozones are found only in a unitary continuous section in Ziyang. It has been proved that the Ziyang section is the one with the most complete sequence of Telychian graptolite biozones in the world.  相似文献   

Diversity history of Ordovician graptolites and its relationship with environmental change     

Zhang YuanDong  Chen Xu 《中国科学D辑(英文版)》2008,51(2):161-171

Statistical analysis based on global data indicated that the planktonic graptolites presented a distinguished pattern from that of benthic communities during the great Ordovician biodiversification. The graptolites started to diversify from the beginning of Ordovician and reached an acme in the early Middle Ordovician, but subsequently underwent a steady decline to the end of Ordovician. During the Ordovician, many clades of the graptolites made their originations, flourishing and replacements. However, in different regions and distinct environments across the world, graptolites may presumably display distinct patterns of radiation and evolution, a hypothesis to be tested. Herein a study of the graptolite diversity in the Early to Middle Ordovician in the Upper Yangtze Region (Platform) and Jiangnan Region (Slope), South China, is conducted. The results indicate that graptolites underwent a remarkable increase in both regions, but with distinct magnitude, scope, process and patterns. The diversification of graptolites in the Upper Yangtze Region, though less prominent, is divided into four stages and includes two peaks. In the Jiangnan Region, the graptolite diversification is far more prominent and includes three stages and one peak. Based on the distinct diversity histories and composition of graptolites in the two representative regions, a 'deep-water origin and shallow-water dispersal' model is proposed for the Ordovician graptolite faunas. According to the model, the major graptolite faunas of Ordovician originated in the deep-water region on the continental slope, the source of the graptolite novelties, and subsequently spread into shallow-water region on the shelf. Besides, we also conduct a comparison study of the Ordovician graptolite diversity in South China and other major regions. The results display that the graptolites diversified globally in the Early and Middle Ordovician. At the beginning of Ordovician, graptolites underwent a significant ecological innovation of graptolites: planktonic forms were derived from their benthic ancestors. This derivation resulted in the great guild expansion of graptolites. In late Early Ordovician (Floian), the global expansion of graptolites commenced. From the Floian to the end of Middle Ordovician, the graptolites diversity increased remarkably and displayed three peaks for all the regions. However, the peaks are somewhat distinct in magnitude and timing among regions. The Darriwilian peak is prominent in both South China and Baltic region, but inconspicuous in Australasia. No close relationship between the graptolite diversification and the palaeolatitudes are supported herein. Instead, the graptolite diversification seems to coincide with the global sea-level rises, suggesting a possible intrinsic relationship between them.  相似文献   

中国紫阳特列奇阶的分带笔石及其层位分布   总被引：2，自引：0，他引：2  

傅力浦  张子福  谢从瑞 《地球学报》2005,26(1):45-52

本文记述了紫阳芭蕉口志留系连续剖面上,特列奇阶的9个生物带和5个亚带分带笔石,以及它们在剖面上的首现和继现层位。认为Loydell(1992,1996)在英国建立的特列奇阶9个笔石带(包括早期的5个亚带)在世界上其他地区如中国紫阳还是可以推广应用的。  相似文献   

海水表面温度变化及其对笔石动物群分布的控制作用     

王传尚  汪啸风  陈孝红  李志宏 《地质学报》2009,83(6):751-758

本文通过对宜昌黄花场剖面和宜昌陈家河剖面大湾组83件样品和陈家河剖面红花园组2件样品的碳氧同位素测试数据,分析了奥陶纪大坪期海水表面温度的变化;并以宜昌黄花场剖面大湾组笔石序列为基础,结合华南地区笔石动物群的分布情况,分析了海水表面温度的变化对笔石动物群地理分布的影响,提出温度变化仅是影响笔石动物群地理分布的间接因素,前人的纬度分带学说值得进一步研究。  相似文献   

四川盐边地区志留纪牙形石生物地层及年代地层   总被引：2，自引：0，他引：2  

金淳泰  钱泳蓁  王吉礼 《地层学杂志》2005,29(3):i007-i008

首次提供了四川盐边地区从下志留统至下泥盆统连续的志留系年代地层系统的实际证据和原始材料,由上而下建立8个牙形石带,2个牙形石组合带和1个笔石带,以此为依据建立了攀枝花阶、永兴阶、箐河阶、叉河阶、透底河阶和支六阶,分别归入下泥盆统、顶志留统、上志留统、中志留统和下志留统,为我国志留系安康阶以上地层的建阶研究工作提供了实际的基础资料。四川盐边地区志留系龙马溪组为笔石相地层,其上全为碳酸盐岩相,其中牙形石发育良好,形成连续完整的牙形石带序列,这对我国和更大的范围壳相志留系年代地层系统对比提供了非常有价值的资料。  相似文献   

皖南赣北宁国组和胡乐组沉积环境的古盐度特征及其地质意义   总被引：6，自引：0，他引：6  

王海峰  俞剑华 《地层学杂志》1994,18(1):9-16

通过对皖南赣北地区早、中奥陶世宁国组和胡乐组合笔石黑色岩系的相当硼含量和镁铝比值的研究,揭示该时期皖南赣北海盆古海水具有不断淡化的历史;宁国组下部沉积环境的古盐度比宁国组上部以及胡乐组沉积环境的古盐度高;古海水发生明显淡化的转折期是在Ｕ．ａｕｓｔｒｏｄｅｎｔａｔｕｓ带（Ｎｒ）与Ｄ．ｅｌｌｅａｓｅ带（Ｎ８ａ）的界线附近;结合笔石动物群组合面貌的变化,古盐度有可能是早、中奥陶世笔石动物群演替的外界环境因素之一。  相似文献   

笔石光学结构的反射率十字图解研究     

刘大锰  王利忠  杜刚  胡宝林 《现代地质》2001,15(3):321-325

应用反射率十字图解研究了中国部分地区下古生界地层中动物有机碎屑笔石的光学各向异性。研究结果表明 ,在成熟度较低时 ,笔石呈现双光轴中性特征 ,即Rmax-Rint≈Rint-Rmin;随成熟度的增加 ,笔石具有明显的双光轴负光性特征 ,即Rmax-Rint相似文献   

康滇地轴东缘古生代生物地层研究     

段志明 《四川地质学报》1998,(2)

作者在１∶５万汉源、甘洛等八幅区域地质调查中,对片区出露的古生代沉积盖层的生物地层层序、古生物化石的产出状态、组合面貌、发育情况等进行了较为详细的研究,自下而上建立了２３个生物化石组合（带）。  相似文献   

基于原位多元素成像分析龙马溪组笔石成因及地质意义     

竺成林  王华建  叶云涛  王晓梅  黄家旋  朱玉梅  杨瑞东 《岩矿测试》2019,38(3):245-259

上扬子地区龙马溪组黑色页岩富含笔石,多以碳质薄膜形式富集于富有机质层段。前期研究多关注笔石形态和成岩后的演化过程,对笔石埋藏和早成岩阶段所经历地球化学作用的研究较少,笔石成因仍缺乏直接证据。本文利用激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)技术对宁203井龙马溪组笔石进行原位微区多元素扫描成像,对主量成矿元素分布与富集程度进行解析,发现了碳质薄膜笔石体表面富集Mg、Al、Si、Fe元素,富集倍数在1.5～10倍以上,Sr/Ba值(1.4～2.3)则明显低于围岩(5.0),指示黏土矿物包埋是笔石碳化的主要途径,包埋形成的硫化微环境导致部分笔石发生黄铁矿化。结合面笔石率、有机质、黄铁矿、黏土矿物含量和δ~(13)C_(org)值的剖面垂向变化及相关性分析,提出早期微生物席繁盛和后期硫酸盐还原菌繁盛导致水岩界面孔隙水普遍缺氧,是笔石和有机质大量埋存的主要原因。本研究结果不仅揭示了龙马溪组笔石的埋藏矿化机制,也为有机质富集和黑色页岩形成的控制因素研究提供了新思路。  相似文献   

Biostratigraphy of Asmari Formation in Ghare Agha seyed of Farsan region,Chaharmahale Bakhtiari Province,Iran     

Seyed Ahmad Babazadeh  Seyedeh Malihe Hamidzadeh 《世界地质(英文版)》2017,20(3)

The Asmari Formation consists of shallow marine sedimentary rocks deposited on ramp setting .Lar-ger benthic foraminifera collected from Asmri Formation are dominated by hyaline and porcelanouse forms , in-cluding Amphistegina, Nummulites, Archaias, Astrotrillina, Miogypsinella, Miogypsinoides, Lepidocyclina, Operculina, Spiroclypeous and Miliolids.The presence of Nummulites cf.vascus in the lower part of the forma-tion allows the age to be determined as Rupelian .The occurrence of Borelis pygmae is an index taxon of the Ru-pelian-Chattian and indicates Early Chattian of SBZ 21-22 in the study section .The first appearance of Mio-gypsinella akadagensis shows Late Chattian ( SBZ 23) and defines the upper boundary of the SBZ 21-22.The new data are the first evidences showing that the shallow marine Asmari Formation is attributed to Oligocene (Rupelian-Chattian) age for this region.  相似文献