Petrochronology of oxidized granulites from southern Peru

Sapphirine–quartz granulites from the Cocachacra region of the Arequipa Massif in southern Peru record early Neoproterozoic ultrahigh‐temperature metamorphism. Phase equilibrium modelling and zircon petrochronology are used to quantify timing and pressure–temperature (P–T) conditions of metamorphism. Modelling of three magnetite‐bearing sapphirine–quartz samples indicates peak temperatures of >950°C at ~0.7 GPa and a clockwise P–T evolution. Elevated concentrations of Al in orthopyroxene are also consistent with ultrahigh‐temperature conditions. Neoblastic zircon records ages of c. 1.0–0.9 Ga that are interpreted to record protracted ultrahigh‐temperature metamorphism. Th/U ratios of zircon of up to 100 reflect U‐depleted whole‐rock compositions. Concentrations of heavy rare earth elements in zircon do not show systematic trends with U–Pb age but do correlate with variable whole‐rock compositions. Very large positive Ce anomalies in zircon from two samples probably relate to strongly oxidizing conditions during neoblastic zircon crystallization. Low concentrations of Ti‐in‐zircon (<10 ppm) are interpreted to result from reduced titania activities due to the strongly oxidized nature of the granulites and the sequestration of titanium‐rich minerals away from the reaction volume. Whole‐rock compositions and oxidation state have a strong influence on the trace element composition of metamorphic zircon, which has implications for interpreting the geological significance of ages retrieved from zircon in oxidized metamorphic rocks.     

Elastic solutions for stresses in a transversely isotropic half‐space subjected to three‐dimensional buried parabolic rectangular loads

In many areas of engineering practice, applied loads are not uniformly distributed but often concentrated towards the centre of a foundation. Thus, loads are more realistically depicted as distributed as linearly varying or as parabola of revolution. Solutions for stresses in a transversely isotropic half‐space caused by concave and convex parabolic loads that act on a rectangle have not been derived. This work proposes analytical solutions for stresses in a transversely isotropic half‐space, induced by three‐dimensional, buried, linearly varying/uniform/parabolic rectangular loads. Load types include an upwardly and a downwardly linearly varying load, a uniform load, a concave and a convex parabolic load, all distributed over a rectangular area. These solutions are obtained by integrating the point load solutions in a Cartesian co‐ordinate system for a transversely isotropic half‐space. The buried depth, the dimensions of the loaded area, the type and degree of material anisotropy and the loading type for transversely isotropic half‐spaces influence the proposed solutions. An illustrative example is presented to elucidate the effect of the dimensions of the loaded area, the type and degree of rock anisotropy, and the type of loading on the vertical stress in the isotropic/transversely isotropic rocks subjected to a linearly varying/uniform/parabolic rectangular load. Copyright © 2002 John Wiley & Sons, Ltd.     

Numerical calculations in the orbital determination of an artificial satellite for a long arc

Numerical methods are usually used for the computation of ephemerides with perturbations for the precise orbital determination of an artificial satellite. But their numerical stability will be encountered in a long arc. In this case the use the improved Encke special perturbation methods has been suggested. The results of this paper show that Encke's method does indeed have a certain effectiveness, but cannot yet completely resolve the numerical stability, and the more efficient method is to use the energy integral or its variational relation to control the growth of the along-track error in general numerical calculations so that the aim of stabilization can be achieved.     

台湾海峡西部柱状沉积物粘土矿物的分析

根据台湾海峡西部10个柱102个样品的X 射线衍射等分析,鉴定了该区粘土矿物组合与含量变化,分析了其与沉积环境的关系.结果表明,该区粘土矿物组合大多数站位以伊利石含量占首位,绿泥石和高岭石次之,且含少量蒙脱石;伊利石含量随距岸、水深的增加而递增,高岭石则反之;蒙脱石含量与火山活动密切相关,绿泥石含量呈斑块状分布;775和819号站有典型的陆相层,为早玉木冰期的“台湾陆桥”或“东山陆桥”提供有力证据.     

Surficial Sedimentary Diatoms in Okinawa Trough and Its Response to Kuroshio Current

This paper describes the relative contents of dominant diatom species and the distributive characteristics of tropical pelagic species and diatom assemblages, and also discusses the relations between the relative content of tropical pelagic species and Kuroshio Current and between the distribution of diatom assemblages and material sources. The results show that the limit of＞20% relative content of tropical pelagic species is basically consistent with the demarcation of Kuroshio Current, and that the distributions of dominant diatom species and diatom assemblages reserve the records of their closer relations to material sources.     

钛胶海水提铀动力学研究Ⅱ——吸附机理的推断

海水提铀机理的研究,已逐渐受到重视,然而,至今研究还不是很深入,观点也各有差别.例如,Keen等[1]认为钛胶从海水中吸附铀是阳离子交换过程,即海水中的铀是UO₂2+离子的形式与钛胶进行交换;尾方升等[2]则倾向于阴离子吸着,即铀是以UO₂(CO₃)₃4-的形式被吸附.我们曾于1973年在海洋局系统的一次会议上提出阳离子给合交换的看法,并在后来的两次专业会议上予以补充发展.张正斌[3]认为是阳离子交换或一价阳离子失水络合.最近崔清晨[4]提出可能是UO₂(OH)₃-的络合吸附.根据几年来的工作,我们仍认为,钛胶从海水中的吸铀机理可能是一种阳离子形式的络合交换过程.     

卤虫的发育与蜕皮

我国北方孤雌生殖卤虫在盐度为60,水温为19—28℃的条件下,自卵内孵出无节幼虫长成至性成熟产仔(无节幼虫或卵),需经蜕皮12—15次,其中多数为14次,历时15—18天,随后每次产仔即行蜕皮一次,本文描述了卤虫各个不同令期发育的外部形态变化,并根据其蜕皮次数和形态特征,将卤虫的发育分为十五令(15th instar)。此外还观察到在孤雌生殖的卵中有发育成为雄性的个体。     

A new type of Shipboard Meteorological Satellite Receiving-processing System

INTRODUCTIONTheSMSRPSisstalledontheshipnavigatingovertheseaandreceivessatellitecloudmapsatanytimetoprovidereliablereal-timedataofmeteorologyandocean.Itisanimportantequipmentforsafeguardofshipnavigation.Chinahasthousandsofoceanicships.Butalmostallships,withonlyveryfewexception,arenotstalledbySMSRPS.Thecausesareasfollows:1.Thetechniqueisverycomplicated.2.Thedevelopmentcostisveryhigh.3.Ifweintroduceforeignequipment,thecostistooexpensive.4.Foreignequipmentanditssoftwarearecompletelyclo…     

中国近海海地瓜属(棘皮动物门：海参纲)的研究

海地瓜属Acaudina Clark,1907是印度一西太平洋印度马来亚区特有的芋海参,从潮间带到水深80米的沿岸浅海很普遍,在我国各海域都有发现,而且数量很多。 曾研究报道过中国海地瓜属的学者有: Semper(1868), Ludwig(1882), Chang(张凤瀛)(1934,1935),Yang(杨佩芬)(1937),张凤瀛等(1964)和Clark(1981)。 海地瓜属形态变化很大,骨片形态也不很稳定,有的完全没有骨片,或者仅在身体后端尾部有骨片,且随个体发育和栖息环境条件而変化。所以,海地瓜属在鉴定上存在很多困难,并且造成了许多混乱。 Sluiter(1912)曾对海地瓜属作了专门的研究,认为下列8个种和变种都是同一种。 有效的种只是模式种 Aphelodactyla molpadioides (Semper)一种。后来，Deichmann (Clak,1938)研究了Sluiter保存在阿姆斯特丹(Amsterdam)的材料,认为Sluiter的结论是正确的。1912年后又陆续发表了几个新种。Clark&Rowe(1971)在《印度-西太平洋区浅水棘皮动物专著》一书中列了下面5个种。 本文对中国科学院海洋研究所多年来在我国沿海采集的全部海地瓜标本(共807个)进行了详细研究。作者认为这一属可能只有两种,一种是海地瓜 Acaudina molpadioides (Semper),另一种是白肛海地瓜 Acaudina leucoprocta (H.L.Clark)。这两种中国都有。同时认为 Acaudina delicata (H.L.Clark)应是Acaudina molpadioides (Semper)的异名，Acaudina irania (Heding) 应是 Acaudina leucoprocta (H.L. Clark)的异名。Acaudina gephyra (Sluiter) 可能是 A. molpadioides (Semper)的非正常个体。本文还对海地瓜属的变异作了描述,这种变异似乎和栖息环境,特别是底质有密切关系。