浅析宁波盆地膏盐地层的时代──兼对“宁波盆地北部的长河群”之时代质疑     

鞠天吟 《浙江国土资源》1995,(1)

宁波盆地地下揭示的一套包含暗色膏硝质泥岩、泥质白云岩在内的紫红、灰紫色泥岩、棕褐色砂砾岩、细砂岩和玻屑凝灰岩的地层，均称方岩组，内含膏盐并具油色显示。对其时代有早、晚白垩世和早第三纪之认识，笔者从70～90年代地质工作中所获化石分析认为，虽然宁波盆地这一层位含化石不丰，但从分布及数量上比较，相对占优势的应该是孢粉和植物化石，其时代意见也较为一致，指示为早白垩世。  相似文献   

The middle pleistocene deposits of Waverley Wood Pit,Warwickshire, England     

F. W. Shotton  D. H. Keen  G. R. Coope  A. P. Currant  P. L. Gibbard  M. Aalto  S. M. Peglar  J. E. Robinson 《第四纪科学杂志》1993,8(4):293-325

A complex of channels underlying the Baginton-Lillington Gravel (Baginton Formation) at Waverley Wood Quarry, Warwickshire is described. Fossil pollen and plant macrofossils, Coleoptera, Ostracoda, Mollusca and Mammalia are described from the channel-fill deposits. Consideration of all the evidence allows the identification of four separate stages of channel fill which largely occurred under a cool temperate climate. At the top of Channel 2 evidence for a cold, continental climatic episode can be recognised, suggesting that the whole complex was deposited under a fluctuating climate at the end of a temperate stage. At two levels in the channels human artefacts were recovered confirming the presence of Palaeolithic people in Warwickshire during the deposition of the sediments. Amino-acid geochronology suggests an age within the ‘Cromerian Complex’ Stage for the channels. The small vertebrate and molluscan faunas indicate that the deposits are no older than the latter part of the ‘Cromerian Complex’ Stage of East Anglia. The regional stratigraphic significance of the Waverley Wood succession is outlined.  相似文献   

The influence of macrophyte growth,typical of eutrophic conditions,on river flow velocities and turbulence production     

Pamela Naden  Ponnambalam Rameshwaran  Owen Mountford  Coralie Robertson 《水文研究》2006,20(18):3915-3938

The influence of emergent and submerged macrophytes on flow velocity and turbulence production is demonstrated in a 140 m reach of the River Blackwater in Farnborough, Hampshire, UK. Macrophyte growth occurs in patches and is dominated by Sparganium erectum and Sparganium emersum. In May 2001, patches of S. erectum were already established and occupied 18% of the channel area. The flow adjusted to these (predominantly lateral) patches by being channelled through a narrower cross‐section. The measured velocity profiles showed a logarithmic form, with deviations attributable to topographic control. The channel bed was the main source of turbulence. In September 2001, in‐stream macrophytes occupied 27% of the channel, and overhanging bank vegetation affected 32% of the area. Overall flow resistance, described by Manning's n, showed a threefold increase that could be attributed to the growth of S. emersum in the middle of the channel. Velocity profiles showed different characteristic forms depending on their position relative to plant stems and leaves. The overall velocity field had a three‐dimensional structure. Turbulence intensities were generally higher and turbulence profiles tended to mirror the velocity profiles. Evidence for the generation of coherent eddies was provided by ratios of the root mean square velocities. Spectral analysis identified deviations from the Kolmogorov ?5/3 power law and provided statistical evidence for a spectral short‐cut, indicative of additional turbulence production. This was most marked for the submerged vegetation and, in some instances, the overhanging bank vegetation. The long strap‐like leaves of S. emersum being aligned approximately parallel to the flow and the highly variable velocity field created by the patch arrangement of macrophytes suggest that the dominant mechanism for turbulence production is vortex shedding along shear zones. Wake production around individual stems of S. emersum close to the bed may also be important locally. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Phaeocystis globosa与Phaeocystis antarctica叶绿体psbA基因的比较   总被引：3，自引：0，他引：3       下载免费PDF全文

杨泽民  章群  谢数涛  韩博平  吕颂辉  Hodgkiss 《海洋科学》2005,29(1):24-28

测定了2株球形棕囊藻Phaeocystis globosa P1、P2的psbA基因序列。发现得到的2个序列完全相同。以P2序列对比分析了P．globosa和P．antarctica的psbA基因在DNA序列、氮基酸序列和RNA二级结构上的差异性，发现2种棕囊藻psbA基因DNA序列和氨基酸序列非常保守，无插入／缺失，其核苷酸和氨基酸变异率分别为1．88％和1．13％。与核基因核苷酸的碱基替换不同，psbA基因核苷酸的碱基替换主要发生在密码子的第1位上。且不引起氨基酸的变化，引起氨基酸变化的碱基替换都发生在密码子的第2位和第3位上。在RNA二级结构上两序列的1～4茎环结构完全相同，表现出明显的棕囊藻属的特异性，其它结构区域差异较大。种间差异表现明显。由于psbA基因DNA序列和氨基酸序列非常保守，可能不适宜棕囊藻属的系统发育分析。但其RNA二级结构可能对于棕囊藻的分子分类有一定的参考价值。  相似文献   

Phylogenetic analysis of Pectinidae(Bivalvia) based on the ribosomal DNA internal transcribed spacer region     

HUANG Xiaoting  BI Ke  HU Jingjie  HU Xiaoli  BAO Zhenmin 《海洋学报(英文版)》2007,26(6):83-90

The ribosomal DNA internal transcribed spacer (ITS) region is a useful genomic region for understanding evolutionary and genetic relationships. In the current study, the molecular phylogenetic analysis of Pectinidae (Mollusca: Bivalvia) was performed using the nucleotide sequences of the nuclear ITS region in nine species of this family. The sequences were obtained from the scallop species Argopecten irradians, Mizuhopecten yessoensis, Amusium pleuronectes and Mimachlamys nobilis, and compared with the published sequences of Aequipecten opercularis, Chlamys farreri, C. distorta, M. varia, Pecten maximus, and an outgroup species Perna viridis. The molecular phylogenetic tree was constructed by the neighbor-joining and maximum parsimony methods. Phylogenetic analysis based on ITS1, ITS2, or their combination always yielded trees of similar topology. The results support the morphological classifications of bivalve and are nearly consistent with classification of two subfamilies (Chlamydinae and Pectininae) formulated by Waller. However, A. irradians, together with A. opercularis made up of genera Amusium, evidences that they may belong to the subfamily Pectinidae. The data are incompatible with the conclusion of Waller who placed them in Chlamydinae by morphological characteristics. These results provide new insights into the evolutionary relationships among scallop species and contribute to the improvement of existing classification systems.  相似文献   

A genetic assessment of the taxonomic status of New Zealand mussels of the genus Xenostrobus Wilson, 1967     

Donald J. Colgan  Richard C. Willan  Lisa A. Kirkendale 《新西兰海洋与淡水研究杂志》2020,54(2):271-285

ABSTRACT

The genus Xenostrobus consists of small, marine and estuarine mussels that all appear similar externally. One of its estuarine species, Xenostrobus securis, with a native range in New Zealand and Australia, has become invasive in the Northern Hemisphere. No genetic data are available to determine if X. securis populations from the two countries are conspecific. Additionally, marine Xenostrobus from New Zealand have often been regarded as a species, X. neozelanicus, distinct fromthe marine Australian species X. pulex. We combined new DNA sequences with published data to assess the taxonomic status of New Zealand Xenostrobus. The data comprised 658 aligned bases of mitochondrial cytochrome c oxidase subunit I (COI) gene and 331 bases of nuclear histone H3. There was no evidence that X. securis populations from Australia and New Zealand are specifically distinct. Northern Hemisphere specimens of X. securis belonged to Australian, not New Zealand, clades in phylogenetic analyses of COI data, suggesting the former country as their more likely original source. The results confirm that X. neozelanicus and X. pulex are distinct species and for nomenclatural completeness for this taxonomic decision a lectotype is designated for Mytilus ater Zelebor in Dunker and Zelebor, 1866 DunkerW, ZeleborJ. 1866. Bericht über die von der Novara-expedition mitgebrachten Mollusken. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien. 16:909–916. [Google Scholar] [?=?Modiolus neozelanicus Iredale, 1915 IredaleT. 1915. A commentary on Suter’s ‘Manual of New Zealand Mollusca’. Transactions of the New Zealand Institute. 47:417–497. [Google Scholar]].  相似文献   

褐牙鲆(♀)、夏鲆(♂)及其杂交子一代线粒体16S rDNA序列遗传特性的初步研究   总被引：2，自引：0，他引：2  

徐晖  肖志忠  孔晓瑜  李军  董晓丽 《热带海洋学报》2007,26(5):60-63

以线粒体16S rRNA基因部分片段为代表研究雌褐牙鲆Paralichthys olivaceus、雄夏鲆P. dentatus及其杂交子一代间线粒体DNA的遗传特性。母本与父本序列差异较大,属种间差异,在590个位点中有28个变异位点,而且全部为简约信息位点。使用同一对引物扩增亲本与杂交子代,在杂交子代中未检测到父本的线粒体DNA类型,11个处于两种生长阶段的杂交样本仅检测到一种单倍型,而且与母本的一个单倍型为同一种,表明褐牙鲆与夏鲆杂交线粒体DNA遵循母系遗传规律。  相似文献   

Spring-spawning herring (Clupea harengus L.) in the southwestern Baltic Sea: do they form genetically distinct spawning waves?     

Hede Jorgensen  Hanne B.; Hansen  Michael Moller; Loeschcke  Volker 《ICES Journal of Marine Science》2005,62(6):1065-1075

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Analysis, synthesis and modelling of high-resolution observations of salt-marsh eco-geomorphological patterns in the Venice lagoon   总被引：1，自引：0，他引：1  

Marco Marani  Enrica Belluco  Sergio Ferrari  Sonia Silvestri  Andrea D'Alpaos  Stefano Lanzoni  Alessandra Feola  Andrea Rinaldo   《Estuarine, Coastal and Shelf Science》2006,69(3-4):414

The present paper describes observations, analyses and models of salt-marsh channel network and vegetation patterns with the aim of contributing to the development of predictive models of ecological and morphological co-evolution. Existing and new observations are described, with particular emphasis on remote sensing and ancillary field surveys, which are shown to allow reliable, accurate and repeatable quantitative characterizations of landform and vegetation properties over the spatial scales of interest. The observed channel network morphological characters are then used as the basis and validation of models describing the emergence of channel network and vegetation spatial patterns. In particular, with reference to observations performed in the Venice Lagoon, the note describes: (i) new, 2-cm resolution, characterizations of channel network geometry obtained from “proximal sensing” photographic observations; (ii) the reliable quantitative maps of salt-marsh vegetation which may be retrieved from hyperspectral remote sensing data and field ancillary observations; (iii) a synthesis of recent and new analyses of the statistical properties of vegetation and landform spatial organization, that may be inferred from the maps so derived; (iv) recent and new conceptual and quantitative ecological and geomorphic models developed and validated by remote-sensing and field observations. A coherent observational and theoretical eco-morphodynamic framework is then proposed.  相似文献   

6个虾种基因组DNA多态性分析   总被引：2，自引：0，他引：2  

许玉德  孙晟 《海洋科学》2001,25(1):9-11

采用RAPD方法检测了罗氏沼虾（Macrobrachium rosenbergii)、绿须虾（Aristeus virilis)、长毛对虾（Penaeus penicillatus)、日本对虾（P.japonicus)、斑节对虾（P.monodon)和周氏新对虾（Metapenaeus joyneri)等6个虾种的基因组DNA的多态性。用20个随机引物扩增得到492个DNA片段，根据这些片段的共享度计算出遗传距离并构建系统树。所得结果从DNA水平上反映出虾类在科属种不同分类阶元亲缘关系的远近，并为虾类现行的分类系统提供了分子生物学依据。  相似文献