There is no such thing as the ‘Ediacara Biota'

The term‘Ediacara Biota’(or many variants thereof)is commonly used to refer to certain megascopic fossils of Precambrian and early Palaeozoic age e but what does the term actually mean?What differentiates a non-Ediacaran‘Ediacaran’and an Ediacaran‘Ediacaran’from an Ediacaran non-‘Ediacaran’?Historically,the term has been used in either a geographic,stratigraphic,taphonomic,or biologic sense.More recent research and new discoveries,however,mean that the term cannot actually be defned on any of these bases,or any combination thereof.Indeed,the term is now used and understood in a manner which is internally inconsistent,and unintentionally implies that these fossils are somehow distinct from other fossil assemblages,which is simply not the case.Continued use of the term is a historical relic,which has led in part to incorrect assumptions that the‘Ediacara Biota’can be treated as a single coherent group,has obscured our understanding of the biological change over the PrecambrianeCambrian boundary,and has confused research on the early evolution of the Metazoa.In the future,the term‘Ediacaran’should be restricted to purely stratigraphic usage,regardless of affnity,geography,or taphonomy;suffcient terminology also exists where reference to specimens on a geographic,taphonomic,or biologic basis is required.It is therefore time to abandon the term‘Ediacara Biota’and to instead treat equally all of the fossils of the Ediacaran System.     

Palynological record from a composite core through Late Cretaceous-early Paleocene deposits in the Songliao Basin, Northeast China and its biostratigraphic implications

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.     

伊朗晚元古代──早古生代古地磁研究

选择伊朗中部、南部及西北部地区的近２０条晚元古代－早古生代完整地层剖面,系统采集Ｓｏｌｔａｎｉｅｈ组、Ｂａｒｕｔ组、Ｚａｉｇｕｎ组、Ｌａｌｕｎ组及Ｍｉｌａ组古地磁样品９６０件．经测试和对比获得结论：Ｓｏｌｔａｎｉｅｈ组记录的地磁极性带为反向,Ｂａｒｕｔ组－Ｌａｌｕｎ组为正向,Ｍｉｌａ组又为反向．此成果完全可与国际地质科学联合会（ＩＵＯＳ）１９８９年建立的全球地层极性柱中相应时代的极性带对比．计算得出５个地层组的古地磁南极位置．古地磁研究表明,晚元古代－早古生代伊朗全境均属稳定地块,处于赤道南侧约１６°的低纬度区．此期间似无大幅度转动和纬度变化．     

震旦系陡山沱组的底与待建的末前寒武系的下界

自1988年末前寒武系工作组成立以来,末前寒武系的建系工作正式开展起来。鉴于寒武纪/前寒斌纪的界线层型已经确定,现在的一个中心议题,是要确定末前寒武系的下界及其层型。     

建议在我国统一使用全球通用的正式年代地层单位——埃迪卡拉系（纪）

震旦系（纪）的涵义屡屡变更,争论不断,出现过许多问题。系名Sinian（震旦系）和系的“层型剖面”都是在选取“末元古系”的正式名称和“金钉子”的国际竞争中没有得到多数国际学者支持的候选名称和候选剖面。我国最新正式修订的“震旦系（纪）”与全球年代地层（地质年代）单位埃迪卡拉系（纪）的概念完全相当。系一级的全球单位一旦正式...     

Characterization of shape and terminal velocity of tephra particles erupted during the 2002 eruption of Etna volcano,Italy

In this paper, we present a complete morphological characterization of the ash particles erupted on 18 December 2002 from Etna volcano, Italy. The work is based on the acquisition and processing of bidimensional digital images carried out by scanning electron microscopy (SEM) to obtain shape parameters by image analysis. We measure aspect ratio (AR), form factor (FF), compactness (CC), and rectangularity (RT) of 2065 ash particles with size between 0.026 and 1.122 mm. We evaluate the variation of these parameters as a function of the grain-size. Ash particles with a diameter of <0.125 mm vary from mostly equant to very equant, ash particles between 0.125 and 0.250 mm have an intermediate shape, and particles with diameters >0.250 mm are subelongate. We find that, on average, particles with a diameter of <0.250 mm are subrounded, particles between 0.250 and 0.50 mm are subangular, and particles >0.50 mm are angular. Using this morphological analysis and an empirical relation between the drag coefficient (C _D) and Reynolds number (R _e) of Wilson and Huang (Earth Planet Sci Lett 44:311–324, 1979), we calculate the terminal settling velocities (V _WH). The comparisons between these velocities and those calculated with the formula of Kunii and Levenspiel (Fluidization engineering. Wiley, New York, pp 97, 1969) (V _KL), which considers ash particles as spheres, show that V _KL are in average 1.28 greater than V _WH. Hence, we quantify the systematic error on the spatial distribution of the mass computed around the volcano carried out by tephra dispersal models when the particles are assumed to be spherical.     

The Oligo-/Miocene Qom Formation (Iran): evidence for an early Burdigalian restriction of the Tethyan Seaway and closure of its Iranian gateways

In the central Iranian Esfahan-Sirjan and Qom basins sedimentation of the Oligo-/Miocene Qom Formation took place on extensive mixed carbonate–siliciclastic ramps. During this time, both basins were positioned at the Eurasian margin of the Tethyan Seaway, which connected the western and eastern regions of the Tethys Ocean at least until the late Burdigalian. During the so-called Terminal Tethyan Event the Tethyan Seaway was then closed due to the collision of the African/Arabian and Iranian/Eurasian plates. Facies analysis of the sedimentary record of both basins indicates paleoenvironments ranging from terrestrial to open marine settings, including mangrove, restricted inner shelf lagoon, seagrass meadow, reefal, and deeper offshore environments. Recognition of eight depositional sequences and elaboration of an integrated biostratigraphic framework (calcareous nannoplankton, planktic and larger benthic foraminifers, gastropods, and pectinids) allow us to construct a basin-spanning stratigraphy. The assignment of the recognized sea-level lowstands to the Ru 3 to Bur 3 lowstands of the global sea-level curve enables a comparison with time-equivalent sections from the Zagros Basin, which was part of the African/Arabian Plate on the opposing southern margin of the Tethyan Seaway. The so calibrated sections display restrictions of the Tethyan Seaway and interruption of the south Iranian gateways between the Qom Basin and the Proto-Indopacific in relation to ongoing plate collision during the early Burdigalian.     

云南高原大地构造与地震机制——云南地震活动之端部效应、地震能囊和机构能流的启示——

研究地震问题 ,不外乎历史继承、控震构造、发震动力源三方面。本文以云南高原为例 ,对此作一综述 ,特别从直观范畴引入端部效应、地震能囊、地球纬向振动机械能流三概念 ,试图对与工程地质相关的地震问题 ,从另一视角作一解释。文中特别介绍了机构能流对板块运动的效应 ,此为作者之一 40多年的物理教学、研究成果 ,虽为国外广泛接受 ,但国内地学界尚显陌生。云南既是世界上最活动的板块碰撞带之一 ,在过去 1 0 0 0多年又有过70 0多次中型上以上毁坏性地震 ,和近 40次毁灭性大震 ,今后中国西部大开发大建设中 ,是不能不加以认真对待的。本文从云南历史地震和大地构造入手 ,以众多的历史文献和传统的构造特征为基础 ,导入三个新观念 ,目的在于希望业内研究同仁注意 ,多方面了解震能力源 ,以便在防范措施上更切合实际 ,把地震的危害性降到最小限度根据工程实例研究 ,所谓端部效应 (TerminalEffectsofStructure) ,就是后续地震常常发生在前期地震之后的构造收敛地带 ,而不是张裂扩散区。后续地震在水平方向上总是向着发震之主、副构造线两端游变移动 ,而决不会再在原先的震中区反复发震 (至少是以 1 0 0年计的短期内 )。当活动断裂的走向与主压应力的方向一致时 ,应力在活动断裂的端部高度集中 ,造成岩体破     

锡林浩特国家气候观象台野外观测站终端远程控制的实现

根据野外观测的实际状况,以及时、准确地采集数据为目标,应用目前比较先进的远程控制技术设计理念和管理思想,将Symantec PCanywhere软件和Winpower电源管理软件以及现有的通信技术资源进行优化、组织和管理,实现了对大气成分观测系统终端的远程控制及UPS电源的远程管理。     

远程服务终端设计

远程服务终端是气象服务的现代化手段,盘锦市气象局立足本地服务,设计了ＷｉｎｄｏｗｓＮＴ网络,与Ｎｏｖｅｌｌ网互联,用户远程终端可访问市局网络,并且设计了Ｗｉｎｄｏｗｓ９５操作系统下的终端软件,提供了卫星云图,天气预报,雨情,水情等防汛抗旱服务的气象,水文信息,软件设计合理,操作简单,功能完备,界面友好。