沉积钙质白云石带状面缺陷的择优取向

作者用透射电子显微镜研究了沉积钙质白云石中的带状面缺陷。在衍衬象中面缺陷呈现出特有的条纹衬度,并具有一定的择优取向,它们沿着｛018｝面排列。面缺陷也可分叉,分枝部分平等于｛2－／10｝面。根据白云石面缺陷的取向,本文提出了鞍状白云石宏观弯曲面和微观面缺陷的取向关系。     

Sedimentation settings of the Vendian Vanavara formation,the Siberian platform

A model of sedimentation settings is elaborated for siliciclastic deposits of the Vendian Vanavara Formation, the Katanga saddle, inner areas of the Siberian platform. Four lithologic complexes are distinguished in the formation. The lower complex is composed of proluvial continental deposits exemplifying a dejection cone of ephemeral streams. Its eroded surface is overlain by second complex largely represented by sandstones of coastal zone, which grade upward into siltstones and shales of deeper sedimentation settings (third complex). Sea transgression advanced in northeastern direction. The fourth complex resting with scouring on the third one was deposited in settings of a spacious shallow-water sea zone: in a tidal flat, sand shoals and islands. Sedimentological data are used to correlate more precisely the Vendian siliciclastic deposits of the Katanga saddle and northeastern Nepa-Botuoba anteclise, and to verify subdivision of the Vanavara Formation into subformations and character of its boundary with the overlying Oskoba Formation.     

SH Wave Propagation in Viscoelastic Media

When comparing solutions for the propagation of SH waves in plane parallel layered elastic and viscoelastic (anelastic) media, one of the first things that becomes apparent is that in the elastic case the location of the saddle points required to obtain a high frequency approximation are located on the real p axis. This is true of the branch points also. In a viscoelastic medium this is not typical. The saddle point corresponding to an arrival lies in the first quadrant of the complex p-plane as do the branch points. Additionally, in the elastic case the saddle point and branch points lie on a straight line drawn through the origin (the positive real axis in the complex p-plane), while in the viscoelastic case this is generally not the case and the saddle point and branch points lie in such a manner as to indicate the degree of their complex values.In this paper simple SH reflected and transmitted particle displacement arrivals due to a point torque source at the surface in a viscoelastic medium composed of a layer over a half space will be considered. The path of steepest descent defining the saddle point in the first quadrant will be parameterized in terms of a real variable and the high frequency solutions and intermediate analytic results obtained will be used to formulate more specific constraints and observations regarding saddle point location relative to branch point locations in the complex p-plane.As saddle point determination for an arrival is, in general, the solution of a non-linear equation in two unknowns (the real and imaginary parts of the complex saddle point p ₀), which must be solved numerically, the use of analytical methods for investigating this problem type is somewhat limited.Numerical experimentation using well documented solution methods, such as Newton's method, was undertaken and some observations were made. Although fairly basic, they did provide for the design of algorithms for the computation of synthetic traces that displayed more efficient convergence and accuracy than those previously employed. This was the primary motivation for this work and the results from the SH problem may be used with minimal modifications to address the more complicated subject of coupled P-SV wave propagation in viscoelastic media.Another reason for revisiting a problem that has received some attention in the literature was to approach it in a fairly comprehensive manner so that a number of specific observations may be made regarding the location of the saddle point in the complex p-plane and to incorporate these into computer software. These have been found to result in more efficient algorithms for the SH wave propagation and a significant enhancement of the comparable software in the P-SV problem.     

四川盆地东部中二叠统茅口组热液活动特征

四川盆地中二叠统茅口组存在丰富的热液流体活动。在野外剖面和岩心观察的基础上,利用多种分析测试方法,对四川盆地东部茅口组碳酸盐岩中的热液活动特征进行了探讨。研究区茅口组热液活动包括2类,一类为硅质热液,表现为薄层硅质岩或硅质团块;另一类为碳酸盐型热液,表现为粗晶方解石和白云石充填在张性构造裂缝中或呈"雪片状"集合体,偶见少量黄铁矿、闪锌矿等金属硫化物伴生。硅质岩主量元素之间的关系表明硅质来源具有多样性,是热液硅与壳源硅的混合;黄铁矿、闪锌矿原位S同位素δ34S介于-3.91‰~-6.87‰之间,推测可能受到了微生物和基性岩浆岩的双重影响;方解石脉和具鞍状双晶的白云石脉普遍具有Ca O高于标准计量、相对富Sr和U、贫REE和Ti、Ce/Ce*明显负异常、Eu/Eu*主体正异常、Y正异常等特征,表明碳酸盐脉为热液活动的产物,流体来源也呈现出火山活动相关流体与富钙地下水混合的特点。闪锌矿富集Ge和Cd,Zn/Cd及Zn/Fe值反映了中等成矿温度。硅质岩和碳酸盐流体包裹体均一温度变化范围较大,介于54.7~294.3℃之间,与稀土元素和微量元素比值所揭示的特征吻合。研究结果表明,穿层状硅质结核和团块的首次出现往往标志着茅口组热液活动的开始,而张性构造裂缝和碳酸盐型热液活动带来的围岩白云化作用则有效地改善了白云岩储集层的物性。     

一种基于Fréchet距离的断裂等高线内插算法

等高线内插是提高地形图精度的一个常用手段，在地图综合等领域中有很重要的作用。在实际地形图数据库中，等高线除了存在完整的计曲线以外，还有一部分断裂的首曲线。已有的等高线内插研究中未考虑对此类数据的处理，为此，本文提出了一种基于Fréchet距离的断裂等高线内插算法。首先提出了等高线度量关系的计算方法，然后对等高线的节点均匀加密，并利用Fréchet距离进行相似度判断以选择参考等高线，最后根据“最近点”的方式进行插值。通过对江苏某地区实际数据的试验，验证了该算法的合理性，对于鞍部地区的内插，有更好的适应性和准确性。     

泰国沙空那空盆地哇伦矿区重力异常特征及钾盐找矿分析

沙空那空盆地处于滇藏印支褶皱系南段,属于印支中央地块,沙空那空盆地已发现他曲、乌隆、廊开、哇伦等多处钾盐矿床,是亚洲重要的蒸发沉积型钾盐矿成盐盆地,本次研究的哇伦矿区便位于该盆地的中心地带。为了解决矿区勘查之初所遇到的困难,本次工作对前人的研究成果进行了仔细分析,提出了前人成果的使用具有一定的局限性;本文结合已有地质、钻探资料,对矿区布格重力异常特征进行了再分析,做出了区内基底构造存在2个次级凹陷的推断,经钻孔验证,表明物探推断是正确的,进而据此圈定了2个找矿靶区,为下一步找矿工作指明了方向。     

一次大暴雨过程的分析

对2010年6月1—2日广西大暴雨天气的湿度场进行了分析。结果发现：暴雨前有一个高湿区的形成和维持过程,暴雨前一天预报的高湿区产生明显调整,导致暴雨出现,表明低层湿度场对暴雨发生有较好的指示意义。     

Huxley方程的定性分析

运用微分方程定性理论，对Huxley方程进行定性分析，得到了方程在有限奇点的稳定性及极限环不存在性的结论，并借助Maple软件做出相图．     

四川盆地东部中二叠统茅口组热液活动特征*

四川盆地中二叠统茅口组存在丰富的热液流体活动。在野外剖面和岩心观察的基础上,利用多种分析测试方法,对四川盆地东部茅口组碳酸盐岩中的热液活动特征进行了探讨。研究区茅口组热液活动包括2类,一类为硅质热液,表现为薄层硅质岩或硅质团块;另一类为碳酸盐型热液,表现为粗晶方解石和白云石充填在张性构造裂缝中或呈“雪片状”集合体,偶见少量黄铁矿、闪锌矿等金属硫化物伴生。硅质岩主量元素之间的关系表明硅质来源具有多样性,是热液硅与壳源硅的混合;黄铁矿、闪锌矿原位S同位素 δ³⁴S 介于-3.91‰~-6.87‰之间,推测可能受到了微生物和基性岩浆岩的双重影响;方解石脉和具鞍状双晶的白云石脉普遍具有CaO高于标准计量、相对富Sr和U、贫REE和Ti、Ce/Ce^*明显负异常、Eu/Eu^*主体正异常、Y正异常等特征,表明碳酸盐脉为热液活动的产物,流体来源也呈现出火山活动相关流体与富钙地下水混合的特点。闪锌矿富集Ge和Cd,Zn/Cd及Zn/Fe值反映了中等成矿温度。硅质岩和碳酸盐流体包裹体均一温度变化范围较大,介于54.7~294.3 ℃之间,与稀土元素和微量元素比值所揭示的特征吻合。研究结果表明,穿层状硅质结核和团块的首次出现往往标志着茅口组热液活动的开始,而张性构造裂缝和碳酸盐型热液活动带来的围岩白云化作用则有效地改善了白云岩储集层的物性。     

基于DEM的山地鞍部点分级提取方法

本文以地形起伏变化较大的陕北黄土丘陵沟壑区为例,通过流域边界线上高程相对低点的自动识别,实现基于DEM数据的地面鞍部点自动获取。实验结果显示,采用该方法所提取的地面鞍部点具有层次结构显著、提取精度高、操作简便、便于确定重要性等级及与山顶点空间关系等优点,对于DEM地形特征点簇的构建与分析具有重要意义。