基于GPS的港口导航系统的设计和实现     

龚咏喜  郭庆胜 《测绘科学》2003,28(2):42-44

根据有关规范,讨论了基于GPS信号的港口导航系统中各种数据的组织与融合的方法和技术,并对用双GPS接收机来确定船体位置和船体方向的两种方案进行了比较和分析。  相似文献   

Environmental history of the south-eastern South Atlantic since the Middle Miocene: evidence from the sedimentological records of ODP Sites 1088 and 1092   总被引：1，自引：0，他引：1  

Bernhard Diekmann  Mareike Fälker†  Gerhard Kuhn† 《Sedimentology》2003,50(3):511-529

  相似文献   

Petrography and chemistry of sandstones from the Swiss Molasse Basin: an archive of the Oligocene to Miocene evolution of the Central Alps   总被引：3，自引：0，他引：3  

Hilmar Von Eynatten 《Sedimentology》2003,50(4):703-724

Abstract Oligocene to Miocene fluvial sandstones from the Swiss Molasse Basin were analysed for sandstone framework composition, heavy minerals, whole‐rock geochemistry and detrital chrome spinel chemistry. Samples were taken from the proximal part of the basin close to the Alpine main thrust and are chronostratigraphically calibrated between 31 and 13 Ma. Sandstone composition allows the identification of different source rocks, and their variation in time and space place constraints on the Oligocene to Miocene evolution of the Central Alps. In the eastern part of the basin, sandstones document a normal unroofing sequence with the downcutting from Austroalpine sedimentary cover into Austroalpine crystalline rocks and, slightly later at ≈ 21 Ma, into Penninic ophiolites. In the central part, downcutting into crystalline basement rocks occurred at ≈ 25 Ma, and the removal of the sedimentary cover was much more advanced than in the east. This may be interpreted as a first signal from the doming of the Lepontine area. At ≈ 20 Ma, extensional tectonics in the hinterland led to the first exposure of low‐grade metamorphic rocks from the footwall of the Simplon Fault in the Central Alps. Erosion of these rocks persisted up to the youngest sediments at ≈ 13 Ma. In the western part of the basin, a contribution from granitoid and (ultra)mafic rocks is documented as early as ≈ 28 Ma. The source for the (ultra)mafic detritus is Penninic ophiolites from the Piemonte zone of the western Alps, which were already exposed at the surface at that time.  相似文献   

Anisotropy of magnetic susceptibility of heated rocks     

Bernard Henry  Diana Jordanova  Neli Jordanova  Christine Souque  Philippe Robion 《Tectonophysics》2003,366(3-4):241-258

Heating produces changes, which does not always correspond to simple enhancement of the magnetic fabric. Two methods are proposed to determine the anisotropy of magnetic susceptibility of the ferrimagnetic minerals formed or that have disappeared by chemical change during successive heating. The first diagonalizes the tensor from the difference between each tensor term before and after heating. The second employs linear regression for each tensor term made with the values obtained throughout a thermal treatment. When the same magnetic fabric is obtained from several thermal steps, it cannot be related to randomly oriented ferrimagnetic minerals. Instead, the newly formed fabric must be related to characteristics of the pre-existing rock. By comparing this ferrimagnetic minerals fabric with the initial whole rock fabric, we can distinguish cases where heating simply enhances pre-existing fabric from those where thermal treatment induces a different fabric. Relative to the pre-heating fabric, this different fabric may simply be an inverse fabric or one whose principal susceptibility axes are oriented in a different direction, related to petrostructural elements other than those defining the initial fabric.  相似文献   

Paleomagnetism of the Upper Proterozoic and Devonian rocks from the K odzko Metamorphic Complex in the West Sudetes (SW Poland): tectonic implications for the Variscan belt of Central Europe     

《Tectonophysics》2003,377(1-2):83

The K odzko Metamorphic Complex (KMC) consists of Upper Proterozoic metaigneous and metasedimentary rocks forming a stack pile thrusted over the Givetian and overlain by Frasnian–Fammenian sediments. Magnetomineralogical experiments show that the magnetic minerals are secondary. The paleomagnetic experiments identified three components of the Natural Remanent Magnetization; labeled A1, A2 and M. The mean pole positions calculated in situ correspond with the Baltica Upper Devonian (A1: PlatS=−18°, PlongE=317°), Permo-Carboniferous (A2: PlatS=−39°, PlongE=2°) and Triassic–Jurassic (M: PlatS=−60°C, PlongE=308°) segments of the Apparent Polar Wander Path (APWP) for Baltica. This indicates that the region studied was situated close to the Baltica plate at least since the Upper Devonian and was not folded after this period.  相似文献   

Quaternary clay mineralogy in the northern South China Sea (ODP Site 1146) —— Implications for oceanic current transport and East Asian monsoon evolution   总被引：4，自引：0，他引：4  

刘志飞  汪品先 《中国科学D辑(英文版)》2003,46(12)

The East Asian monsoon system is a thermodynamic atmospheric circulation induced by the different potential heating between the 揥estern Pacific Warm Pool?(WPWP) and the Asian continent. The circulation patterns dominate seasonal patterns of winds, preci…  相似文献   

南极石生地衣主要生物风化作用研究进展与展望   总被引：1，自引：0，他引：1       下载免费PDF全文

陈杰  檀满枝 《极地研究》2003,14(1):65-72

地衣以物理、化学方式参与矿质基质的风化作用 ,诱导和加速岩石的风化过程。本文对南极地区表生和内生型地衣的生物风化作用进行了综合论述 ,详细阐述了不同地衣种类诱导和参与几种主要岩石类型 (砂岩类和火成岩类 )风化作用的模式、机制、过程以及产物。同时指出 ,地衣等其他生物因素间接参与的风化过程 ,地衣导致的岩石抗风化效应以及生物风化速率等方面的研究工作是目前南极生物风化作用研究方面的新领域。  相似文献   

Ab initio Hartree–Fock study and charge density analysis of beryl (Al4Be6Si12O36)     

M. Prencipe 《Physics and Chemistry of Minerals》2002,29(8):552-561

 An ab initio Hartree–Fock calculation on beryl structure has been performed and the wave function has been used for an analysis of the electron density. The equilibrium geometry, determined by minimizing the energy with respect to cell parameters and fractional coordinates, is in good agreement with structural experimental measurements; small differences in length between the various Si–O bonds of the structure are well reproduced by the calculation. The two non-equivalent oxygen atoms (O1 and O2) of beryl show different electron distributions. In particular, the valence shell charge concentration (VSCC) of O1 (the bridge between two Si ions) has a torus-like shape, showing a bulge on the external side of the Si–O–Si angle and a thinning on the internal side of it; by contrast O2 has two lone pairs which are approximately located on the line for O2, normal to the plane passing, on average, through the atoms O2, Si, Be and Al. The electron density of each oxygen is strongly polarized toward the Si ions and much less polarized towards the other cations. Such features of the VSCC of the oxygens can be recast in terms of the valence bond theory, to explain the observed differences in bond lengths. By calculating the potential inside the channels of the beryl structure, predictions could be made about the positions occupied by alkali cations, which are often found in natural minerals belonging to the beryl group: results agree in general with experimental findings, but foresee a shift of such cations off the central positions located on the six fold symmetry axis. Additionally, calculations of position and orientation of H₂O inside the channel, in the alkali-free beryl, locate the molecule close to the basal plane, with the H⋯H axis parallel to [001] or oriented at 40^∘ from it. Received: 12 December 2001 / Accepted: 6 April 2002  相似文献   

广西大厂亢马矿区金、银分布特征研究     

姚意莎 《矿产与地质》2002,16(4)

详细研究了亢马矿区主要金属矿物赋存状态及金银分布特征 ,指出各种矿物中 Au、Ag含量及回收利用的价值  相似文献   

Les minéraux techniques naturels : connaissance,typologie et propriétés d'usageNatural technical minerals: investigation,typology and utilisation properties     

Jacques Yvon  Jean-Maurice Cases  Frédéric Villiéras  Laurent Michot  Fabien Thomas 《Comptes Rendus Geoscience》2002,334(9):717-730

By nature minerals are heterogeneous materials for many of their properties. These properties also vary according to composition and structure fluctuations, compared to definitions. Technical minerals are used in applications where their performances depend on intrinsic properties and processing conditions. It is possible to base rankings on simple criteria, allowing estimating the abilities of minerals for each utilisation. The research of the corresponding mechanisms concerns the molecular level. These questions are discussed for kaolins, raw materials for baked clays, talqueous materials and montmorillonites. To cite this article: J. Yvon et al., C. R. Geoscience 334 (2002) 717–730.  相似文献