Structural control of the Gagua “Wedge” Zone east of Taiwan Island on the southern Okinawa Trough

The sea area east of Taiwan Island is a unique ac-tive arc-continental collision margin in China and even in the world with the NE-nearly EW extending Ryu-kyu trench-arc-backarc basin system on the east and the nearly N-S extending Manila trough and Luzon arc on the west. The sea area east of Taiwan Island differs from the Ryukyu trench-arc-basin system in structural property, but there is a certain genetic relation between the two (Fig. 1)[1-3]. Since the 1990s, many investigations and …     

Assessment of some spatial and temporal issues in landslide initiation within the Río Aguas Catchment, South–East Spain

A research programme underway in south–east Spain has the overall aim of developing a long-term landscape evolution model for the Tertiary depositional basins that lie within the eastern part of the Betic cordillera. As part of the work it has become apparent that there are multiple natural hazards to development in the region, and the nature and distribution of these is presently under investigation. For one hazard, namely landsliding, a database of over 300 cases has been compiled within one defined 425 km² river catchment, namely the Río Aguas. Evaluation of the database has demonstrated that the contemporary distribution of landslides correlates with areas of steepest slopes across a range of the different lithologies. However, the “slope” component of the landscape is controlled by a wave of incision associated with a river capture event c. 100000 years ago which locally increased erosion by between 5 and 10 times. This event was a function of differential uplift between the depositional basins and resulted in over-steepened slopes within parts of the catchment which have yet to reach equilibrium in this evolving landscape.     

Structural control of the Gagua "Wedge" Zone east of Taiwan Island on the southern Okinawa Trough

Based on compositive analysis and interpretation of the observed and historical data, the geophysical field characters and structural properties of the Gagua "Wedge" Zone of the sea area east of Taiwan Island and the primary tectonic stress direction and its variabilities of backarc spreading in the southern Okinawa Trough are studied. It is concluded from the study results that the Gagua "Wedge" Zone is structurally consistent with the Gagua ridge and two fault basins on both sides of the Gagua ridge, and adjusts the moving direction and distance of the western Philippine Sea plate to make the northwestward motion of the plate on its east side change to the northward subduction of the plate on its west side so that the primary tectonic stress direction of the Okinawa Trough changed from NW-SE to nearly N-S, which provided the stress source for the Okinawa Trough to enter the second spreading stage.     

粤东嵩溪银-锑矿床地质特征及成因探讨

论述了嵩溪银-锑矿床地质特征、矿化富集规律,并通过对矿床的构造环境、矿石结构构造、成矿物理化学条件等的分析,得出矿床成因为火山喷流沉积-热液改造型矿床的结论.     

甘肃省三危山断裂带东段--片石山一带的韧性变形特征

三危山断裂隶属阿尔金断裂体系，处于华北板块与塔里木板块的结合部位。在玉门镇幅1／250000的区域地质调查中，发现三危山断裂带东段一甘肃省玉门镇片石山一带存在着早古生代和晚古生代两期不同性质、不同层次、不同构造组合样式的韧性变形。     

东海大桥(大乌龟近岛段)工程地质条件分析

文章介绍了东海大桥(大乌龟近岛段)地形、地貌特征、地基岩体分布特征及中、微风化岩体的物理力学特征，并分析了场地节理及破碎带发育特征，在此基础上，评价了场地地基稳定性及建设适宜性。     

长江口南汇东滩水动力条件变化的数值预测

南汇东滩紧邻长江口主要排沙通道南槽而成为泥沙沉降的一个重要部位,为促淤围垦提供了有利的滩地和来沙条件,是上海市规划围垦的重点区域。目前上海已在南汇东滩开始实施围垦工程,围垦工程改变了长江口南汇岸线,也改变了南汇东滩的水动力条件。为了解围垦工程实施后水动力条件的变化,采用二维潮流数学模型模拟南汇东滩促淤围垦工程实施前后流场的变化,探讨围垦工程对邻近水域水动力产生的影响,为预测圈围工程实施后南汇东滩变化提供水动力学依据。     

羌塘东部治多县啊聂托确黑云母二长花岗斑岩体特征及其构造意义

啊聂托确二长花岗斑岩体,岩石类型单一,其单颗粒锆石U-Pb年龄为126±3.8Ma,形成于早白垩世.低铝(Al2O3＜15%),低钛,低钠,属轻稀土元素富集型,富集大离子亲石元素K,Ba,Rb,高场强元素Th,Nb,Ta,P,略显亏损,Ti,Y较强亏损.εSr(t)为107.6～80,εNd(t)为1.9～3.1.具有壳幔混合产物的特征.构造背景为火山弧花岗岩.