Crustal seismic profiles in the Alboran Sea — Preliminary results

In September 1974, deep seismic sounding experiments were performed in the Alboran Sea. The crustal seismic profiles were carried out with shotpoints at sea along approximately the 36°N parallel and along 3°W and 5°W meridians with stations on land in Morocco and Spain following these three directions. The first interpretation of the data indicates a thinned continental crust with a Moho depth of 16 km on top of a slightly anomalous upper mantle (7.5<V _p<7.9 km/s) beneath the center of the Alboran Sea. Towards Spain the transition to the continental margin is characterized by a very rapid thickening of the crust. Towards Morocco a rather abrupt thickening is observed only for the Rif region, while in the eastern part (north-south profile along 3°W) the dip of the Moho is very slight.     

盈江铀矿的新资料

本文第一次提供了由单晶X射线衍射分析测定的盈江铀矿的空间群和晶胞参数。该矿物产于广东省下庄铀矿田。斜方晶系,空间群Bmmb(63),a=15.707(3),b=17·424(3),c=13.692(2)?,V=3747?~3,Z=4。Dc=4.60g/cm~3,Dm=4.54g/cm~3。化学式:(K_2,Ca)(UO_2)_7(PO_4)_4(OH)_6·6H_2O。二轴晶,负光性。2Vc=36°,2Vm=36—38°。Ng=1.707(2),Nm=1.703(2),Np=1.666(1)。光性方位:Ng//Y,Nm//X,Np//Z。     

Good, bad or 'necessary evil'? Reinterpreting the colonial burning experiments in the savanna landscapes of West Africa

A simple ecological model underlies contemporary fire policy in many West African countries. The model holds that the timing (or seasonality) of annual savanna fires is a principal determinant of vegetation cover. The model's origin can be traced to the ideas held by influential colonial scientists who viewed anthropogenic fire as a prime force of regional environmental degradation. The main evidence in support of the model derives from the results of a series of long-term burning experiments carried out during last century. The experimental results have been repeatedly mapped onto fire policy often taking the form of a three-tiered model in which fire exclusion is considered the ultimate management objective, late dry-season fire is discouraged and early dry-season fire is allowed but only under specific, often state-controlled circumstances. This paper provides a critique of contemporary fire policy in the region and the fire ecology model on which it is based. Through an analysis of burn scars for the 2002–3 fire season generated from ETM+ imagery, the study documents the spatiotemporal pattern of burning for an area in southern Mali. It argues that current policy, which is informed by an a-spatial model, cannot adequately account for the critical pattern of burning that is characteristic of the region. A reinterpretation of the burning experiments is presented in light of four factors: empirical data; recent developments in patch-mosaic theory; historical evidence on the effects of fire suppression; and data on indigenous burning strategies, all of which suggest a need to reconsider current fire policy.     

华北东濮凹陷异常高压与流体活动及其对储集砂岩成岩作用的制约

Basin-Mod软件模拟显示东濮凹陷35Ma左右孔隙流体已出现较高异常压力，综合分析表明欠压实作用是发育异常高压的主要机制，处于异常高压带内的泥岩存在微裂隙带，是异常高压流体压裂的直接结果并可以成为流体运移的通道，通过典型研究区砂岩压实（溶）量，压实－胶结关系，沉积参数－储集物性的对比，表明异常高压流体的确对砂岩的压实作用具有抑制作用，另一方面，自生石英流体包体均一温度大部分在105－145℃之间，频数呈多峰式展布，可能显示幕式流体活动。该温度范围内由于没有有机酸的大规模生产，泥岩频繁发生的幕式流体泄压活动，使得富含CO3^2-的高压流体在注入砂岩（低压区）孔隙后易与Ca^2 ,Mg^2 ,Fe^2 等离子结合，导致砂岩储层发生强烈的（晚期）碳酸盐沉淀和胶结作用。     

THE IMPACTS OF GLOBAL CHANGE ON DESERTIFICATION IN CHINA

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库车前陆盆地天然气成藏过程及聚集特征

天然气的组分和碳同位素主要受母质类型和成熟度双重因素的控制,这是我们研究天然气的基础。但是越来越多的证据显示成藏过程对天然气组分和碳同位素也具有明显的控制作用。尽管库车前陆盆地不同构造单元的天然气来源一致,即主要来源于侏罗系烃源岩、其次为三叠系烃源岩,但是库车前陆盆地冲断构造带、斜坡区和前缘隆起区在天然气组分、干湿程度和碳同位素组成上具有明显的差异。库车前陆盆地经历了早期油气的聚集、破坏和晚期天然气聚集、调整的过程,研究认为成藏过程对库车前陆盆地不同构造单元的天然气组分和碳同位素特征具有明显的控制作用。     

A New Model for Ice Forces on A Conical Structure

The ice force is an important factor to be taken into account for offshore structures in cold regions, and the calculation method of the ice force is meaningful for the offshore structure design. The cone is now used as an optimal ice-resistant structure because it can cause bending failure of the ice sheet. The interaction between an ice sheet and a conical structure is studied in this paper and Croasdale‘s model is modified based on field observations. The newly built model separates the ice sheet into the emersed part and the floating part, and the equilibrium analyses are canied out respectively. The bending moment distribution of the ice sheet is analyzed for the determination of the position of bending failure, which serves as a supplementary restraint. The analytic solution of the ice foree on a conical structure is obtained it is verified with the experimental data of previous researches.     

西藏高原斜压对流边界层风、温、湿廓线特征

利用1998年夏季第2次青藏高原大气科学试验当雄观测站的边界层观测资料以及拉萨、改则和武汉等地探空资料,分析讨论西藏高原斜压对流边界层风、温、湿廓线的特征. 研究结果表明,高原地区白天对流边界层发展可高达2200m,显著超过中纬度平原地区和海面上对流边界层高度. 高原对流边界层中温度廓线具有较好的混合特征,湿度廓线有时在某一高度上出现湿度极大值. 高原对流边界层内热量和水汽收支分析表明,水平平流作用对边界层结构具有重要作用. 在对流边界层中平均风速垂直分布存在风切变现象. 水平温度梯度形成较强的斜压性是形成边界层风切变的主要原因.     

东营凹陷沙河街组三段层序低位域砂体沉积特征

本文基于构造层序分析和基准面分析原理，利用测井曲线，岩相等资料，重点研究了东营凹陷沙三段3个层序的低位域砂体沉积特征，发育规律及其石油地质意义。应用构造坡折带的概念在该凹陷划分出了4种构造坡折带样式。研究表明：该凹陷沙三段层序低位域砂体发育下切水道充填，低位楔和低位扇。构造坡折带的发育特征和样式控制了低位域砂体的时空展布特征。构造坡折带控制下的低位域砂体发育在层序底部，构造坡折带附近，成藏条件优良，是隐蔽油气藏勘探的主要方向。