A NUMERICAL MODEL FOR SEDIMENTATION IN FENHE RESERVOIR AND THE ADJOINING REACHES

In this paper, a numerical model for sedimentation in Fenhe Reservoir and the adjoining reaches has been presented on the basis of the theory of non-equilibrium sediment transport. The model is calibrated by using a part of the sediment data collected for Fenhe Reservoir and checked by simulating the remaining data. Moreover, the method of optimization in nonlinear programming has been applied to determine the basic parameters of the model applying a concept of fuzzy mathematics to formulate the objective functions. The computed amounts of reservoir deposition and channel deformation arc found to be substantially in agreement with the values observed.     

垭头铀矿床控矿沉积相及成因

垭头铀矿是湘西沅麻盆地白垩系红层中较为典型的沉积矿床,位于盆地东北缘,靠雪峰隆起,置于Z_b,(?)_(1x),地层之上。本文是在综合野外实践的基础上,研究矿床的沉积特点、控矿沉积相以及矿床成因。     

萨拉乌苏河地区地层中的碎屑矿物及其所反映的中更新世末期以来之气候环境变化

文章根据对萨拉乌苏河地区第四纪地层中的碎屑矿物分析结果,将重矿物按其抗化学风化的能力不同分为不稳定、较稳定、稳定和极稳定四种类型,不同层位的重矿物类型的百分含量不同,从而可求出重矿物的风化系数HW。不同时期地层的HW不同,而HW的大小变化与化学风化的程度有很大关系,一般来说,化学风化作用强,HW相应变小。而化学风化作用的强弱又主要受气候的影响,从而可推测该时期气候环境的变化。     

Fault－weakening effect of reservoir temperature of hot spring and its influence on seismic activities

Ｆａｕｌｔ－ｗｅａｋｅｎｉｎｇ　ｅｆｆｅｃｔ　ｏｆ　ｒｅｓｅｒｖｏｉｒ　ｔｅｍｐｅｒａｔｕｒｅ　ｏｆ　ｈｏｔ　ｓｐｒｉｎｇ　ａｎｄ　ｉｔｓ　ｉｎｆｌｕｅｎｃｅ　ｏｎ　ｓｅｉｓｍｉｃ　ａｃｔｉｖｉｔｉｅｓ（林元武）Ｆａｕｌｔ－ｗｅａｋｅｎｉｎｇｅｆｆｅ...     

松辽盆地白垩纪古气候特征及其变化机制

本文综合研究了松辽盆地白垩纪古气候的沉积记录、孢份古植物群记录及碳、氧同位素地球化学特征，得出了松辽盆地白垩纪古气候的演变规律。并认为碳族国与古气候旋回有密切的对应关系，大气中ＣＯ＿２含量的变化是古气候变化的根本原因。每一温暖时期的开始都与大气中ＣＯ＿２含量的增加有关，随着固碳作用的增强，温室效应削弱。碳旋回是古气候变化的重要机制。     

Possible impact of shallow interfluve traps on groundwater remediation

Shallow stratigraphic traps exist in certain geologic environments, which might complicate groundwater remediation efforts. Too often, pump-and-treat remediation wells are installed in geometric patterns designed to maximize cleanup operations. If, however, shallow stratigraphic traps are present, certain contaminants may be locally trapped and thus missed during cleanup operations. Alternatively, if shallow stratigraphic traps are delineated prior to location of cleanup wells, fewer wells may be needed for remediation. For example, a single well located at the trap apex, coupled with a single injection well, might be sufficient if: (1) all contaminants were contained in the trap, and (2) the trap was not laterally extensive. Interfluve stratigraphic traps are formed when braided outwash sands are subsequently covered by backswamp or lacustrine clay deposits. Such traps are common near-surface features of the valley train deposits of the Lower Mississippi River Valley and have relief of a few tens of centimeters to perhaps in excess of 10 m. Interfluve traps are also expected to commonly occur in many glaciated regions. Due to channel migration during backswamp clay deposition, and differing thicknesses of clay cover, it is unlikely that all interfluve traps can be delineated by a single method. Therefore, several geological techniques that might be useful in delineating shallow interfluve traps are briefly discussed here, as well as potential complications in using the described methods.     

黄河流域旱涝年地面热量收支变化特征

根据北京、郑州３年热量平衡观测资料，建立波文（Ｂｏｗｅｎ）比计算模式。并用此模式及辐射计算式等估计黄河流域８年５－８月地面月辐射收支、蒸发耗热、湍流热交换量和土壤热交换量，并比较分析旱涝年它们的差异以及随旱涝（用降水距平表示）的变化。      

塔里木盆地北缘兴地断裂构造变形特征

兴地断裂发生在中元古代末期，使中元古巨厚的沉积岩发生了强烈褶皱和隆起，并伴有大量岩浆侵入和区域变质作用。在兴地断裂形成的同时，发生了第一期构造变形，其特点以韧性变形为主，由三个变形幕构成，形成了本区主要构造骨架；晚元古代本区进入晋宁期发展阶段，团结的塔里木地台基底局部裂开，形成一系列近东西向的断陷盆地，发生了第二期变形，形成以塑性变形为主的板劈理和千枚理为其特征。该期变形结束了塔里木基底发展，进入了稳定盖层沉积发展阶段；进入早古生代，兴地断裂控制了该时期的沉积作用，之后发生第三期变形，以脆性变形为主，形成一系列碎裂岩和脆性变形组构，使兴地断裂形成几十米乃至上百米宽的破碎带，从而改造了早期的糜棱岩；至中、新生代，兴地断裂再次活动，形成断裂两侧南升北降的扭动形迹。通过对兴地断裂的深入探讨，笔者认为：该断裂具有线性特征明显，活动时间漫长，构造变形复杂，是塔里木盆地北缘规模巨大的复活大断裂。     

钱塘江流域的地球化学质量平衡研究

从地球化学角度出发，对钱塘江流域的物质平衡关系及起控制作用的化学风化反应进行了探讨和计算。结果表明，降雨提供了河水中大部分的Ｋ~＋、Ｎａ~＋和ＳＯ~２－＿４。另外，灰岩地区碳酸钙的溶解反应提供了河水中大部分的Ｃａ~２＋和ＨＣＯ~－＿３，硅酸盐岩地区钠长石和黑云母生成高岭石的风化反应提供了剩余的Ｋ~＋、Ｎａ~＋、Ｈ＿４ＳｉＯ＿４和大部分的Ｍｇ~２＋及少量的ＨＣＯ~－＿３。石膏和白云石的风化反应控制了ＳＯ~２－＿４和Ｍｇ~２＋的平衡，其中碳酸钙的溶解反应占主导地位。流域的化学侵蚀率和机械剥蚀率分别为０．０２２和０．０７１（ｋｇ·ｍ－２·ａ－１），碳酸盐岩区的物质流出量是硅酸盐岩区的２倍。     

Flow and grainsize pattern in a sharply curved river bend

The main characteristics of river flow and grainsize in a bend of the sand bedded meandering river Dommel, The Netherlands, are presented. Measurements were carried out at a relatively low discharge in a sharply curved bend following a long straight reach. In the studied bend, secondary circulation is restricted to the thalweg area; only in the downstream part of the bend it exists over the entire cross-section. Therefore, on the entire pointbar platform, which comprises the larger part of the bend, the median sedimentation diameter of the bedload material is governed by the distribution of the longitudinal components of the bed shear stress only.