太平洋中部微生物与多金属结核的生成关系

作者采用洋底水-岩-微生物相互作用系统的观点首次对太平洋中部洋底多金属结核开展了微生物成矿作用的研究。通过洋底各介质中微生物活动与多金属结核生成机制、成矿物质转化的微生物作用及化学作用对比模拟实验研究、观察和测定系统中成矿物质浓度及环境参数的变化,揭示了成矿组分由微生物活动引起的反应速度和演变方向;从微生物地球化学作用的观点,论证了多金属结核微生物成矿机制和成矿模式;提出了多金属结核微生物成矿阶段和成矿理论。     

鄂东南古岩溶岩系的识别及其时空发育特点

古岩溶及其成矿作用的研究是鄂东南多金属成矿带沉积学和矿床学工作的较薄弱环节之一。作者依据大量野外观测资料,提出识别该区古岩溶岩系的地层、构造、形态和岩石学等四种标志及其古岩溶岩系的成因分类方案,对古岩溶在时间、空间上发育之强度、多期性及其优先发育部位亦作了分析,并阐述岩浆活动对该区古岩溶发育的影响。最后对古岩溶岩系的生成环境,形成作用和时间进行初步探讨。     

Textural analysis and modelling of a flood deposit: River severn,U.K.

Samples of sediment collected from the Severn floodplain between Worcester and Gloucester following the severe flooding in January and February 1990, were analysed for their grain size distribution. The results show that most sand was deposited within 20 m of the channel bank, but that fine sand may contribute to flood sediment across the width of the floodplain. James' (1985) numerical model of overbank sedimentation attempts to predict the transfer of sediment to the floodplain during flooding. Geometrical and hydraulic data relating to the Severn flood are used as input for a computer program of James' (1985) model. The pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment. The patterns were found to be similar, so James' (1985) model was considered to predict in a relative sense the distribution of flood sediment.     

衡山花岗岩体西缘韧性剪切带的特征,成因及岩体定位机制

衡山花岗岩体由南岳岩体(早期)和白石峰岩体(晚期)组成,衡山岩体西缘形成有分带明显的韧性剪切带,向西倾斜,在XZ面上呈倾向滑动剪切运动,矿物显微变形构造显示为倾向简单剪切特征。经测定,韧性剪切带形成时温度下限为343.6℃,古差应力下限为52～62MPa,应变速率下限为2.05×10~(-14)/s-3.13×10~(-14)/s,推算总位移量在13.5km左右。在花岗岩体以外没有韧性剪切变形现象,说明该韧性剪切带是衡山岩体定位过程中由白石峰岩体沿南岳岩体边缘侵位的简单剪切作用所形成。     

湘西北下寒武统黑色页岩伴生元素研究新进展

湖南大庸慈利的镍钼多金属矿床是湘西北下寒武统黑色页岩中伴生元素镍钼及铂族元素等富集最好地段。该矿床中的硅岩应属典型的喷气岩；特殊的筒状富矿体，以及Ｎｉ、Ｍｏ、Ｃｕ、Ｚｎ、Ｓｅ、Ａｓ、Ｂａ、Ａｕ、Ａｇ、Ｐｔ族元素特殊组合；矿石中金属硫化物呈胶状产出，显示快速堆积特征。     

新生代黄骅坳陷构造伸展、沉积作用和岩浆活动

黄骅坳陷是一典型的张性盆地,其构造主要受西缘向东倾的拆离断层的控制。构造沉降分析显示盆地西部以裂谷沉降为主,而向东热沉降逐渐增大,反映了上地壳的强烈裂谷区与岩石圈深部强烈减薄区发生了错位。沉积作用在裂谷期和热沉降期具明显不同的特点,指示了早期基底快速不均匀的下沉和晚期基底广泛缓慢下沉的过程。玄武岩的形成和演化也与盆地构造发展过程相一致。研究结果表明,黄骅坳陷是在下伏岩石圈上部发生简单剪切和下部发生纯剪切的构造伸展过程中形成的。     

论地质作用中元素间的相关性及制约因素

本文把地质作用中元素间的相关性划分为曲线相关、准线性相关和线性相关三种类型;并在建立反映岩浆、沉积作用过程中元素间相关关系的数学模型及其它工作的基础上,详细讨论分配系数、源区成分和作用过程等方面对地质作用中元素间相关关系的制约作用。进而获得批式熔融、结晶分异、岩浆混合、化学沉积、碎屑沉积等过程中元素间呈线性和(?)线性关系的一般特征和应用前景。最后还给出La/Ce相关性的应用实例。     

SILTATION RATE IN A TRENCH DREDGED ON FLOODPLAIN IN ESTUARY

I. INTRODUCTIONA discharge of 100--200 m3 / s is needed to be diverted from a tidal reach and utilized as cooling water for a Droposed power plant in the Yangtze Estuary. The diversionchannel is divided into two parts by a levee along the river bank, an open channel stretchinside the levee is connected with a trench dredged on the floodplain, as shown in Pig. 1.Since the flow and sediment regimes in these two stretches are different, analysis is madeseparately for each of them.11. ESTI…     

Meanders caused by hyperconcentrated water flow: An example from the loess plateau,China

This paper describes meandering alluvial rivers with mean annual suspended-sediment concentrations of more than 100 kgm^?3 on the Loess Plateau, China, and explains their formation as caused by the effect of hyperconcentrated water flow. When the river is dominated by hyperconcentrated flow, the rate of energy expenditure required for sediment transport declines significantly. Accordingly, the river channel adjusts itself to a lower channel gradient by increasing the river length, resulting in a meandering channel. Since the stable transportation of sediment by hyperconcentrated flow is dependent on river channel boundary conditions, the latter play an important role in the formation of meanders of this kind. The paper also discusses the conditions for the discrimination of meandering and braided rivers in this area.