三疣梭子蟹(Portunus trituberculatus)卵子发生、激活与早期卵裂的细胞学观察

采用连续切片和光镜技术,对三疣梭子蟹卵子发生、激活和早期卵裂进行了细胞学观察.结果表明,在发育及再发育的卵巢中,三疣梭子蟹卵子发生主要经历了卵原细胞的增殖和初级卵母细胞的分化、生长、成熟这两个阶段.依据卵子发生过程中雌性生殖细胞形态的变化,这两个阶段又可细分为卵原细胞期、卵黄发生前卵母细胞期、小生长期、大生长期、近成熟卵母细胞期和成熟卵母细胞期等6期.成熟卵母细胞处于第一次减数分裂中期,这可作为卵子成熟的形态学标志.第一次减数分裂中期纺缍体长轴的旋转可以发生于卵巢中,与精子及海水的刺激无关.初级卵母细胞达到形态和生理上都成熟的时间窗口很窄.精子入卵引起卵子的激活和减数分裂的完成.23℃下离体培养时,第一和第二极体分别在卵产出后约40min和2h释放.雄原核的形成早于雌原核.雌、雄原核在卵产出后约5h通过联合形成合子核.卵产出后约6h,受精卵处于第一次核分裂后期,但卵裂沟直到卵产出后13h才能观察到,此时核已完成了2次分裂,形成合胞体胚胎.     

基底非均一性对琼东南盆地新生代构造变形差异的影响: 来自物理模拟实验的启示

琼东南盆地位于南海北部大陆边缘西北部,是新生代形成的北东向伸展盆地,其断裂走向、次级凹陷分布方向、构造样式等在东西部表现出明显差异。文章采用构造解析与构造物理模拟相结合的方式,探究先存的中生代构造几何形态及基底性质差异对琼东南盆地东西部构造差异性演化的控制作用。实验结果表明：（1）先存构造薄弱带几何边界分布方向与区域伸展方向共同控制了琼东南盆地主要断裂的走向以及断裂构造样式。由于先存构造薄弱带边界方向存在东西差异,在早期NW向拉伸阶段（Tg-T80）盆地断裂系统在东西部就已表现出明显的分段特征。西部由于垂向拉伸产生一组NEE向断裂;东部由于斜向拉伸,发育至少两组方向的断裂,一组与应力方向垂直（NEE向）,另一组沿着构造薄弱带分布（WE向）。后期断裂活动继承和改造了这一时期的断裂,使断裂系统更加复杂。先存构造薄弱带几何形态变化是导致琼东南盆地东西部构造差异性发育的主控因素。（2）基底强度差异性对上覆构造的断裂数量以及地貌起伏特征有一定影响。琼东南盆地在东西部的断裂走向及构造样式上的差异性受基底强弱、先存构造形态及构造应力方向的共同控制。     

“不协调伸展”作用下裂陷盆地断层的形成演化模式

应用"不协调伸展"的目标砂箱模拟实验成果和新的脆性断裂力学模型——"不协调性准则",分析了裂陷盆地断层形成和演化的控制影响因素,建立了裂陷盆地断裂系统形成和演化的新模式——"不协调伸展"模式。该模式显示:"不协调伸展"的递进变形过程是导致裂陷盆地断裂系统的复杂性的根本原因,实质是不同方向、性质和规模的基底先存构造(主要是先存断裂)的活动性方面存在差异,导致所控制形成的断层在走向、形成的先后次序、规模等方面存在差异,从而形成复杂的断层组合;"不协调伸展"模式是裂陷盆地断裂系统形成和演化的基本型式,复杂的断裂系统可以在方向不变的区域伸展构造作用下在递进变形过程中逐渐形成;裂陷盆地断裂系统虽然比较复杂,但断层的形成和演化是有序的,分布是有规律的,可以通过"不协调性准则"加以分析和预测。     

Release of sulfur- and oxygen-bound components from a sulfur-rich kerogen during simulated maturation by hydrous pyrolysis

An immature sulfur-rich marl from the Gessosso-solfifera Formation of the Vena del Gesso Basin (Messinian, Italy) has been subjected to hydrous pyrolysis (160 to 330°C) to simulate maturation under natural conditions. The kerogen of the unheated and heated samples was isolated and the hydrocarbons released by selective chemical degradation (Li/EtNH₂ and HI/LiAlH₄) were analysed to allow a study of the fate of sulfur- and oxygen-bound species with increasing temperature. The residues from the chemical treatments were also subjected to pyrolysis–GC to follow structural changes in the kerogens. In general, with increasing hydrous pyrolysis temperature, the amounts of sulfide- and ether-bound components in the kerogen decreased significantly. At the temperature at which the generation of expelled oil began (260°C), almost all of the bound components initially present in the unheated sample were released from the kerogen. Comparison with an earlier study of the extractable organic matter using a similar approach and the same samples provides molecular evidence that, with increasing maturation, solvent-soluble macromolecular material was initially released from the kerogen, notably as a result of thermal cleavage of weak carbon–heteroatom bonds (sulfide, ester, ether) even at temperatures as low as 220°C. This solvent-soluble macromolecular material then underwent thermal cleavage to generate hydrocarbons at higher temperatures. This early generation of bitumen may explain the presence of unusually high amounts of extractable organic matter of macromolecular nature in very immature S-rich sediments.     

Stress field and seismicity in the Indian shield: Effects of the collision between India and Eurasia

Intraplate stresses and intraplate seismicity in the Indian subcontinent are strongly affected by the continued convergence between India and Eurasia. The mean orientation of the maximum horizontal compression in the Indian subcontinent is subparallel to the direction of the ridge push at the plate boundary as well as to the direction of compression expected to arise from the net resistive forces at the Himalayan collision zone, indicating that the intraplate stresses in the subcontinent, including the shield area, are caused by plate tectonic processes. Spatial distribution of historic and instrumentally recorded earthquakes indicate that the seismic activity is mostly confined to linear belts while the remaining large area of the shield is stable. The available conventional heat flow data and other indicators of heat flow suggest hotter geotherms in the linear belts, leading to amplification of stresses in the upper brittle crust. Many of the faults in these linear belts, which happen to be 200–80 m.y. old, are being reactivated either in a strike-slip or thrust-faulting mode. The reactivation mechanisms have been analyzed by taking into consideration the amplification of stresses, pore pressures, geological history of the faults and their orientation with respect to the contemporaneous stress field. The seismicity of the Indian shield is explained in terms of these reactivation mechanisms.     

De-bugging the 'millipede' porphyroblast microstructure: a serial thin-section study and 3-D computer animation

ABSTRACT Seventy-five spatially orientated, serial thin sections cut from a single rock containing ‘millipede’ porphyroblast microstructure from the Robertson River Metamorphics, Australia, reveal the three-dimensional (3-D) geometry of oppositely concave microfolds (OCMs) that define the microstructure. Electronic animations showing progressive serial sections of the 3-D microstructure are made available via the World Wide Web. The OCM amplitudes decrease regularly from a maximum in near-central sections to a minimum in near-marginal sections, whereas the OCM interlimb angles increase regularly from a minimum in near-central sections to a maximum in near-marginal sections. These observations illustrate that the OCMs are noncylindrical surfaces with culminations located in near-central sections. Because the porphyroblast cores appear to have been present before significant development of the syn-OCM foliation, all of the OCMs were formed by heterogeneous extension around these cores. The overall geometry of the OCMs described here reflects the strain state, and cannot be used to constrain deformation paths.     

浅变质岩石中的叠加韧性剪切带——以吉林桦甸二道甸子地区为例

吉林省桦甸市二道甸子金矿区的板岩、千枚岩中,存在着平行叠加式和垂直叠加式两个类型的韧性剪切带。它们叠加在早期变形构造之上,显示出不同的构造特征。前者以含“叶理鱼”的疙瘩状千枚岩为特征,“叶理鱼”的含量决定了其应变强度。后者以折劈构造成带状发育为特征,折劈的不同类型决定了其应变强度。     

以声发射估计岩石试样先存应力的新方法

利用声发射话动的凯塞（Kaiser）效应测定岩石先存最大应力已成为声发射技术的重要应用领域。目前,判断岩石凯塞效应对应应力的方法仍被重视。作者在研究岩石在单轴压缩条件下的声发射话动时发现:除了通过凯塞效应可测定岩石的先存最大应力之外,还可根据重复加载时声发射话动的某些特点推断出加载前的先存最大应力,从而进一步验证和提高了利用凯塞效应测定先存最大应力的可靠性。重复加载时声发射话动在一定技术条件下会出现这样的特点:在应力达到第一次加载的最大应力值时出现凯塞效应;而在此之前,当应力达到加载前岩石的先存最大应力值时,声发射话动相对其前后有所特殊。作者认为,这种现象可能反映了材料对先前经历过的损伤的记忆能力。本文初步探讨了这一现象的物理基础。     

History and regional development. A controversy over the ‘right’ interpretation of the role of history in the development of the Polish regions

There is currently a lively discussion on the role of historic memories and the re-visiting of historic legacies in post-communist countries. Using the example of Poland and its legacy of the tripartite division of the 19th century, this paper aims to illustrate how symbolic conflicts over identity politics and the interpretation of history may critically influence discourses on the debates on, and portrayals of, variations in regional development. The paper thus discusses the post-war history of Poland in the context of the so-called left-right political cleavage, and the varying related debates on the ‘quality’ of regional development as part of Poland’s post-communist restructuring. These discussions include varying projections of the nature and role of social capital and its relative ‘usefulness’ for a successful development Poland’s after communism. And there are clear political overtones to these contrasting portrayals of Poland’s history and its regionally varying legacy. Drawing on different definitions of the notion of social capital, the paper then discusses how different legacies, such as an introspective and extrovert outlook of population and institutions, and the degree of cohesion among them, circumscribes a region’s economic development prospects.     

最大有效力矩准则及相关地质构造

摩尔-库伦准则广泛用以说明断裂构造的形成,然而却不能解释自然界广泛分布的大变形。最近提出的岩石变形新理论--最大有效力矩准则,其数学表达式为Meff=0.5(σ1-σ3)L.sin2α.sinα。式中,σ1-σ3代表变形岩石的屈服强度,L为单位长度,α为σ1与变形带间的角度。该准则证明最大有效力矩出现在σ1轴左右54.7°方向,55°±10°区间力矩无显著变化,天然和实验的全部观测值全部位于该区间内。相关地质构造包括:膝褶带、伸展褶劈理、膏盐层中的屈服带、低角正断层、高角逆断层、结晶基底中的菱网状剪切带、地震反射剖面中的鳄鱼嘴构造和前陆盆地中的拆离褶皱等。据该准则可确定有关构造形成时的应力状态和运动学涡度,并扩展说明深俯冲超高压岩石的折返-出露机制。