Volume change during sediment diagenesis and the development of growth faults

The stress system induced the weight of a sediment and the pore fluid it contains, termed the passive stress system, is capable of deforming the sediment. This volumetric deformation is examined with respect to the evolution of porosity and permeability during burial. The effect of this self deformation on the shape of growth faults and normal faults in extensional terrains is considered.     

Anomalous giants in Magellanic Cloud clusters

Many of the populous intermediate-age star clusters (theblue globulars) of the Magellanic Clouds have a few stars that occupy a “forbidden zone” in the colour-magnitude diagrams of the clusters, where stellar evolutionary theory does not predict that stars should lie. The properties of these stars in 13 clusters are gathered in Table 1, where it can be seen that the absolute magnitudes of the stars correlate with the cluster age, lying at a mean value of 2.7 mag above the tip of the main sequence. Several hypotheses regarding their nature are discussed, and it is concluded tentatively that they represent an unpredicted advanced stage of evolution from the giant branch, though no theoretical evidence supports such a conclusion. Considerably more observational data are needed before a more positive statement can be made. Visiting Astronomer, Cerro Tololo Inter-American Observatory, which is supported by the National Science Foundation under contract No. AST 78-27879.     

中国大陆岩石圈结构、盆地构造和油气运移探讨

文中在研究了中国大陆壳内与上地幔高导层的分布和成因的基础上 (由于篇幅所限 ,中国大陆壳内与上地幔高导层分布及其成因在另文给出 ) ,首先对中国大陆岩石圈热状态和地壳热状态进行了定量分析 ,提出了冷、热岩石圈 ,冷、热地壳和冷、热盆地的概念 ,根据岩石圈的变形、热状态和构造活动性 ,提出了刚性岩石圈和塑性岩石圈的概念 ,根据岩石圈的动力学特征对中国大陆盆地进行了分类研究。在此基础上 ,对处于不同地区的大型盆地的构造特征和油气运移规律进行了分析。阐述了前人各种油气模式及其存在的问题后 ,探讨了地壳深部热流体对油气的生成和运移的作用。最后 ,认为在有壳内高导层的盆地中 ,深部流体可向上地壳中的生油和储油层提供大量的热流体 ,并产生高流体压力 ,对油气运移起了主导作用。     

辽东古元古代富镁质碳酸盐岩建造菱镁矿滑石矿床成矿流体研究

辽东地区古元古代大石桥组中分布有富镁质碳酸盐岩建造，并产有大型或超大型菱镁矿、滑石矿床。笔者等近期在该地区野外工作中发现了沉积型石膏岩，并对其和菱镁矿滑石围岩进行了相应的稳定同位素和流体包裹体研究。稳定同位素分析结果为δ^13C一般-1．8‰～ 1．2‰、δ^18Ol0‰～20‰，δ^14SVCDT23．9‰～26．5‰；结合菱镁矿和白云岩流体包裹体形态和成分特征，笔者等认为早期镁质非金属矿床的形成与古元古代的海相蒸发岩系有关，古海水演化而来的变质成矿流体对后期滑石矿床的形成起着重要的控制作用。     

贵州盘县地区峨眉山玄武岩铜矿的成矿地质条件

以峨眉山玄武岩底部与中二叠统茅口组灰岩接触界面上赋存的黄见坑-哈树富铜矿带为例，论述了这一新类型玄武岩铜矿的成矿地质条件及峨眉山玄武岩浆喷-溢对Cu(Au、Pb、zn、Pt、Pd、Sb、F等)元素的富集和后期热液改造成矿作用，以扩大找矿思路。     

吉林省四平辽源地区电法找水效果

本文以四平辽源地区利用电法寻找地下水为例,论述了电法异常曲线特征与地下水之间关系,总结了利用电阻率联合剖面法、激电法在地下水探测中的应用效果;指出了不同地质条件下地下水赋存的电性特征。     

拟准检定法用于划分不同运动趋势块体

利用位移观测数据区分不同形变趋势块体一般分三步进行:基准检测、块体范围区分和各块体内异常形变检测．本文提出用拟准检定法来实现这三步．前两步初选拟准观测是关键．对于基准检测，按形变位移量大小；对于块体范围区分，则按形变方向．最后，通过一个模拟算例，简单介绍了每一步的实施步骤，并比较了拟准检定法与抗差估计(Huber)法、假设检验法的检测效果．结果表明，拟准检定法可以将上述三步成功实现，而抗差估计法只能检测出块体内的异常形变，对稳定基准检测和块体范围划分是失败的；假设检验法在该三步检测中均为失败．从而验证了拟准检定法具有粗差定位准确、崩溃污染率高的优越性．      

低纬平均经圈环流异常与海表温度异常关系的诊断分析

利用NCEP/NCAR的40年大气再分析资料中的月平均经向风速及垂直速度，计算了纬向平均经圈环流的质量流函数，分析了纬向平均的海表温度和纬向平均的经圈环流的气候态及异常态特征，结果表明，（1）南、北半球Hadley环流圈的共同上升支偏于赤道附近的夏半球一侧，与[SST↑-]极大值位置相对应；强下沉支位于冬半球一侧；（2）El Nino事件中低纬[SST]′是异常经圈环流产生的重要外强迫源，但其影响程度受基本气流和[SST↑-]及[SST]′的季节变化和年际差异的影响甚大。     

Mantle Redox State Evolution in Eastern China and Its Implications

Using the secondary spinel standard, the authors have precisely measured the Fe3+/∑ Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, and estimated the oxygen fugacities recorded by 63 mantle xenoliths through olivine-orthopyroxene-spinel oxygen barometry. The results indicate that the oxygen fugacities of the lithospheric mantle in eastern China are higher in the south than in the north. Among them, the oxygen fugacity of the North China craton lithospheric mantle is the lowest, similar to that of the oceanic mantle, while that of Northeast and South China are the same as that of the global continental mantle. The variations of mantle redox state in eastern China are mainly controlled by the C-O-H fluids derived from the asthenospheric mantle. According to the mantle oxidation state, it can be concluded that the C-O-H fluids in the lithospheric mantle of eastern China consist mainly of CO2 and minor H2O, but CH4-rich fluids should come from the asthenosphere where the ox     

Role of fluids in surface deformation caused by the 1999 Chi‐Chi earthquake in Taiwan

The 1999 Chi‐Chi earthquake significantly altered the landscape of central Taiwan. Surface deformation produced by the earthquake along the trace of the Chelungpu thrust can be classified into two styles: (1) uplift without significant surface rupture, and (2) uplift accompanied by surface rupture. Here we examine areas that exhibited the first style of deformation (e.g. Wufeng). Seismic stress at the time of the main shock may have been relieved by high pore‐fluid pressure in a 300‐m‐thick sand and gravel aquifer. Along the thrust fault, frictional heating of these sediments resulted in thermal expansion and an increase in pore‐fluid pressure. High pore‐fluid pressure damped seismic‐wave energy and enhanced intergranular slips of unconsolidated sandy and gravel sediments, which were possibly assisted by sulphuric acid corrosion, leading to a high sulphate content in the groundwater (c. 70 mg L^?1). These changes permitted surface folding and terrace‐style uplifting to occur without significant rupture. In contrast, other areas in which the second style of deformation is dominant (e.g. Fengyuen‐Shihkang) have thin (0–10 m) sand and gravel deposits and lower concentrations of sulphate (c. 30 mg L^?1) in groundwater. In these areas, sediments were heated but not sufficiently to produce significant thermal expansion and increase in pore‐fluid pressure; accumulation of stress in these locations led to rupture at the ground surface, with the formation of steep fault scarps. The areas exhibiting the first deformation style are characterized by the presence of high pore‐fluid pressure, frictional heat conduction, and possibly chemical corrosion related to sulphuric acid attack and formation of sulphate, in contrast to those involving significant uplift and surface rupture. The areal distribution of these two surface deformation styles suggests that the aforementioned fluid‐related subsurface processes may have altered the characteristics of sediments and caused diverse responses to the quake. Copyright © 2002 John Wiley & Sons, Ltd.