南极乔治王岛阿德默勒尔蒂湾火山活动时空演化          下载免费PDF全文

邢光福  王德滋  金庆民  沈渭洲  陶奎元 《极地研究》2002,14(1):22-34

在乔治王岛中部的阿德默勒尔蒂湾 ,凯勒半岛、于尔曼山嘴和埃内坎角是第三纪火山岩集中分布区。野外地质调查和同位素年代学研究表明 ,凯勒半岛发生了三期火山喷发 (三个火山喷发旋回 ) ,同时伴随着火山活动中心的不断北移 ;在第二期火山喷发之后 ,火口塌陷 ,形成破火山 ,之后在半岛北部又发生火山喷发 ,并向东迁移到于尔曼山嘴。因此凯勒半岛是一复活破火山 ,火山活动具有随时间迁移的特性。埃内坎角火山活动虽与上述两地区大致同时 ,但化学成分上不存在明显演化关系 ,应属另一相对独立的火山活动中心  相似文献   

The Bivalve Yangtzedonta is not the Brachiopod Xianfengella   总被引：2，自引：0，他引：2  

YU Wen Nanjing Institute of Geology  Palaeontology  Chinese Academy of Sciences  Nanjing  Jiangsu  China 《《地质学报》英文版》2005,79(6):770-776

Abstract The alleged ＂holotype＂of the bivalve Yangtzedonta primitiva Yu.1985 figured by Qian （2001） is a broken and distorted specimen of the brachiopod Xianfengella prima He and Yang, 1982 and not the holotype of Y. primitiva. Qian contends that the oldest recognized monoplacophoran, Maikhanella pristinis （Jiang, 1980）, is neither a monoplacophoran nor the oldest molluscan fossil in the Meishucunian Stage of China. Furthermore, he considers that the oldest bivalve Xianfengoconcha eUiptica Zhang, 1980 is an inarticulate brachiopod, not a mollusc. WatsoneUa yunnanensis （He and Yang, 1982）, is associated with Yangtzedonta primitiva Yu but indicates no evolutionary relationship between the Classes Rostroconchia and Bivalvia in the Lower Cambrian Zhongyicun Member of the Yuhucun Formation. Qian＇s confusion in using non-molluscan fossils to discuss the early evolution of shelled molluscs also confuses the basic concepts of the respective groups.  相似文献   

Revision of the Clam Shrimp Genus Magumbonia from the Upper Jurassic of the Luanping Basin,Hebei,Northern China     

Peter BENGTSON  Helmut WILLEMS  Hiramichi HIRANO 《《地质学报》英文版》2009,83(1)

The diverse clam shrimp Nestoria-Keratestheria fauna is widely distributed in the Dabeigou Formation in northern Hebei and eastern Inner Mongolia of China.Its important component genus Magumbonia from the Dabeigou Formation in the Luanping Basin,northern Hebei,China,is revised on the basis of a scanning electron microscope (SEM) examination of the type species M.jingshangensis Wang,1984,which revealed morphological features not recognized previously.These include coarse reticulation on the umbo and promi...  相似文献   

东昆仑西端布喀达坂峰地区二叠纪孢粉型化石的发现     

宋泰钟  尹磊明  欧阳舒  王秉璋  王瑾  叶占福  宋生春 《地层学杂志》2004,28(2):142-147

在东昆仑西端布喀达坂峰地区二叠纪地层中首次发现陆相孢粉与海相疑源类化石一起保存的孢粉—疑源类化石组合。经对两个样品较为丰富的孢粉型化石研究后发现,上部组合以裸子植物花粉占优势,双囊无肋花粉最多,可与塔里木盆地的卡伦达尔组的孢粉组合做粗略的比较,但组合中出现了时代偏晚的Ephedripites及Taeniae-sporites,因此,研究区马尔争组中段复理石地层的时代当为中二叠世—晚二叠世。  相似文献   

安徽淮南群四顶山组燧石Sm-Nd年龄测定   总被引：1，自引：0，他引：1  

杨杰东郑文武  陶仙聪王宗哲 《地质论评》2004,50(4):413-417

在对苏皖北部的上前寒武系进行了矿物学研究基础上,选择安徽北部淮南群四顶山组燧石作为测定对象,系统测试Rb-Sr和Sm-Nd同位素,应用Sm-Nd等时线方法进行了定年。本次研究表明,安徽淮南群四顶山组燧石可能是在海洋环境中形成,主要反映了陆源物质特征,其形成时代约为800Ma。这为苏皖北部地区上前寒武系是位于华北区青白口系和扬子区震旦系之间的一套地层提供了一个新的证据,也进一步印证了淮南生物群属于先伊迪卡拉期的学术观点。  相似文献   

太湖MS岩芯重金属元素地球化学形态研究   总被引：21，自引：4，他引：17  

刘恩峰  沈吉  刘兴起  朱育新 《地球化学》2004,33(6):602-610

采用BCR三步提取法对太湖MS岩芯沉积物中Cu、Fe、Mn、Ni、Pb和Zn等6种重金属元素的化学形态进行了研究.结果表明,有效结合态的Cu、Ni和Pb主要以有机物及硫化物结合态、Fe-Mn氧化物结合态存在,Fe和Zn主要以Fe-Mn氧化物结合态存在,Mn主要以可交换态及碳酸盐结合态存在;Fe-Mn氧化物结合态的Ni、Pb和Zn与可还原态的Mn有较好的正相关关系,有机物及硫化物结合态的Cu、Mn、Ni、Pb和Zn与有机碳含量有较好的正相关关系;重金属形态分布体现了重金属元素地球化学性质的差异,以及重金属形态含量与沉积物理化性质的关系.沉积岩芯重金属元素形态垂向变化规律及次生相富集系数表明,Cu、Mn、Ni、Pb和Zn在沉积岩芯13～4 cm有效结合态含量较稳定,为自然沉积;4～0 cm有效结合态含量明显升高,存在一定程度的人为污染.根据137Cs测年结果判断,沉积岩芯Cu、Mn、Ni、Pb和Zn等重金属污染开始于20世纪70年代末期,主要污染元素及污染历史与太湖流域污染工业类型及经济发展阶段相吻合.  相似文献   

太湖沉积物中重金属的地球化学形态及特征分析   总被引：24，自引：2，他引：22  

袁旭音  王爱华  许乃政 《地球化学》2004,33(6):611-618

用连续提取法分析了太湖沉积物5种重金属的地球化学形态,对地球化学形态的组成和地理特征进行了分析研究.重金属地球化学形态配分的共同特点是可交换态最低,残渣态最高.两种形态中Cd的可交换态最高,Cr的残渣态最高,可交换态最低.Cd的碳酸盐态较高,Cr的最低;Pb、Cd的Fe-Mn氧化态较高,Cu的偏低;Cu的有机态最高,Cd的最低;Zn的地球化学形态比例大都处于中间.地域上变化较大的元素是Cd和Cu,变化不明显的元素有Pb和Zn.化学成分中Fe2O3、MnO与重金属地球化学形态的相关性最好,TOC与Cu的形态相关系数最高.综合对比分析表明,太湖沉积物重金属的生物有效性以Cd为最高,其次为Pb.  相似文献   

^12（12）CO,^13（13）CO and C^18（18）O observations along the major axes of nearby bright infrared galaxies     

Qing-Hua Tan  Yu Gao  Zhi-Yu Zhang  Xiao-Yang Xia 《天体物理学报》2011,(7):787-810

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Seasonal timing of stratospheric final warming associated with the intensity of stratospheric sudden warming in preceding winter   总被引：1，自引：0，他引：1  

HU JingGao  REN RongCai  XU HaiMing  YANG ShuangYan 《中国科学:地球科学(英文版)》2015,(4):615-627

The association of seasonal timing of stratospheric final warming events(SFWs) in spring and the occurrence of major and minor stratospheric sudden warming events(SSWs) in midwinter were investigated through statistical analysis, parallel comparison, and composite analysis, based on the NCEP-NCAR reanalysis dataset covering 1958–2012. It was found that the intensity and occurrence of winter SSW events can largely affect the timing of spring SFWs. Specifically, the SFW onset dates tend to be later(earlier) after the occurrence(absence) of winter major SSWs. However, the occurrence or absence of minor SSWs does not change the frequency of early and late SFWs. A parallel comparison of the temporal evolution of the anomalous circulation and planetary-waves between major SSW and minor SSW winters indicates that the stratospheric polar vortex(polar jet) will keep being anomalously stronger 30 days after major SSW onset. And the associated significant negative Eliassen-Palm(EP) flux anomalies can persist for as long as 45 days after major SSW events. In contrast, the circulation anomalies around the occurrence of minor SSW events can last only a few days. To further verify the possible influence of the occurrence of major SSWs on the seasonal timing of SFWs, composite analysis was performed respectively for the 21 major-SSW years, 15 minor-SSW years, and the 15 non-SSW years. Generally, planetary-wave activity in the extratropical stratosphere tends to be stronger(weaker) and the westerly polar jet is anomalously weaker(stronger) in major-SSW(non-SSW) winters. But in the following spring, the planetary-wave activity is weaker(stronger) accompanied with an anomalously stronger(weaker) stratospheric polar vortex. In spring after minor-SSW years, however, the stratospheric polar vortex and the westerly polar jet exhibit a state close to climatology with relatively gentle variations.  相似文献   

Principal aspects of the Ordovician biotic radiation     

ZHANG Yu  ong  ZHAN RenBin  FAN JunXuan  CHENG JunFeng & LIU Xiao LPS  Nanjing Institute of Geology  Palaeontology  Chinese Academy of Sciences  Nanjing  China 《中国科学:地球科学(英文版)》2010,(3)

The Ordovician radiation is among the major bioevents in earth history that have drawn great attention from geologists all over the world, and there have been hundreds of publications treating various aspects of this radiation. The study of the event involves a broad spectrum of research fields and concerns many scientific questions. Many opinions and hypotheses have been proposed on the triggering and controlling factors of the radiation. Herein the authors critically review the study of the Ordovician rad...  相似文献