Far field effects of Alpine plate tectonism in the Iberian microplate recorded by fault-related denudation in the Spanish Central System

Apatite fission track analysis was performed on 56 samples from central Spain to unravel the far field effects of the Alpine plate tectonic history of Iberia. The modelled thermal histories reveal complex cooling in the Cenozoic, indicative of intermittent denudation. Accelerated cooling events occurred across the Spanish Central System (SCS) from the Middle Eocene to Recent. These accelerated cooling events resulted in up to 2.8±0.9 km of denudation in the western Sierra de Gredos and 3.6±1.0 km in the central and eastern Gredos (assuming a paleogeothermal gradient of 28±5 °C and a surface temperature of 10 °C). The greatest amount of denudation (5.0±1.6 km) occurred in the Sierra de Guadarrama. Accompanying rock uplift was 4.7±1.0 and 5.9±1.6 km in the eastern Gredos and Guadarrama, respectively. Most denudation in the Gredos occurred from the Middle Eocene to the Early Miocene and can be related to the N–S stress field, induced by the Pyrenean compression. In the Guadarrama, the greatest denudation was Pliocene to Recent of age and seems related to the ongoing NW–SE Betic compression. The fact that the formation of the E–W trending Gredos coincides with the N–S Pyrenean compression and the creation of the present day morphology of the NE–SW trending Guadarrama with the younger NW–SE Betic compression, indicates that they record the far field effects of Alpine plate tectonics on Iberia. The trend of pre-existing lineaments was of major importance in influencing the style and magnitude of these of far field effects.     

内蒙古北山重点成矿远景区主要地质特征与矿产资源潜力评价方向

本文根据北山地区区域地质背景、成矿地质条件及矿产分布特征,对北山地区初步划分出几个重点成矿远景区,建议作为今后进行区域固体矿产资源潜力评价的方向。     

GEOCHEMICAL EFFECTS OF MAJOR ELEMENTS DURING FLUID-ROCKS INTERACTION IN MARINWOBO FAULT IN THE SOUTH MARGIN AREAS OF ALTAI MOUNTAINS

There are four types of metamorphic rocks in the Marinwobo fault, i. e, cataclasite, mylonite,mictosite and migmatitic granite, and the formation of these rocks is due to the progressive metamorphism of the pyroclastics. The fluids play a very important role in the metamorphic process of these rocks in the Marinwobo fault, the most important feature is that the fluids not only result in the migration of the major elements of the deformation rocks, but also result in the volume loss of the deformation rocks in the deformation process. Thus the migration laws of the major elements in different stages of the progressive metamorphic process are discussed according to mass balance equations. Finally, the quantitative analysis of the mass loss and volume loss of the different rocks the in Marinwobo fault is discussed in this paper.     

Experimental Study on Mine Spoils During Superficial Geochemistry Processes

Based on the mineral and chemical compositions of spoils taken from the Shilu Cu-Mo deposit and Hetai gold deposit, the leaching and batch experiments were made on spoils taken from these two deposits using the leaching column designed by the authors. The experimental results showed that it is not always true that the mine drainage is acidic. Its acidity depends on acid-buffering capacity of gangue, host rock and its alteration mineral assemblage. The composition of the drainage water is related with the interaction between superficial or underground water and solid materials in the spoils, including minerals, hydroxides and amorphous substances. The leaching extent of the element is related with its occurrence form in the deposit. The preferential flow results in leaching-out of heavy metals in large amounts. So it is important to prevent the generating of preferential flow in the system. The results will provide very important grounds for the comprehensive management of land and ecological rehabilitation of the mine site.     

可调滞回模型的磁流变阻尼器及其试验

本文在现在磁流变阴尼器性能研究的基础上，提出了可调滞回模型的磁流变阻尼器及其试验方法，并进行理论、试验及算例分析。首先，根据恒定电流下磁流变阻尼器的阻尼力滞力特性，利用磁流变材料特性的电流（即磁场）可控特点，建立了变电流下的阻尼力滞回模型；其次，在中通过电路板控制外加电流与装置变形间的函数关系，实现了变电流调节的阻尼力滞回模型；最后，将磁流变阻尼器与橡胶隔震装置结合，形成智能磁流变隔夺装置，并对一个单自由度隔震结构进行了数值仿真分析。     

中原地区M≥6级地震后的减(增)震效应

通过对中原地区1500年－2000年所有19次M≥6级地震后空间图像的分析，初步认为M≥6级地震发生后平均63年内，在距原震中平均176km内无M≥5级地震发生，全部19次震例均呈现出内部减震效应，而在其外围出现地震增强的活动图像特征，增震效应对应率为72％。这种强震后的减（增）震效应，不仅对地震危险性分析，而且对1年尺度以上的地震趋势预测均有一定的意义。     

Principal axes of m-DOF structures PartⅠ:Static loading

This paper is the first in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic loads. The primary purpose of this series is to understand the magnitude of the dynamic response of structures to enable better design of structures and control modification devices/systems. Under idealized design conditions, the structural responses are obtained by using single direction input ground motions in the direction of the intended control devices/systems,and by assuming that the responses of the structure is decoupleable in three mutually perpendicular directions. This standard practice has been applied to both new and retrofitted structures using various seismic protective systems. Very limited information is available on the effects of neglecting the impact of directional couplings (cross effects - of which torsion is a component) of the dynamic response of structures. In order to quantify such effects, it is necessary to examine the principal axes of structures under both static and dynamic loading.This first paper deals with quantitative definitions of principal axes and "cross effects" of three-dimensional structures under static load by using linear algebra. It shows theoretically that, for three-dimensional structures, such principal axes rarely exist. Under static loading conditions, the cross effect is typically small and negligible from the viewpoint of engineering applications. However, it provides the theoretical base for subsequent quantification of the response couplings under dynamic loads, which is reported in part Ⅱ of this series.     

PRELIMINARY NUMERICAL STUDY OF TOPOGRAPHIC EFFECTS OF THE TIBETAN PLATEAU ON SURFACE DIRECT RADIATION*

To improve the simulating ability of a model,this paper presents a scheme of calculating direct radiation at land surface with topography in the model.A numerical study is conducted for the topographic effects of the Tibetan Plateau on the direct radiation using NCEP terrain data.Results show that,after taking account into the topographic radiation effect,the regional average of the radiation over the Plateau obviously increases in the local early morning and late afternoon,but changes less around noon.The effect is stronger in winter than that in summer.And heterogeneous topography has also affected the distribution of the radiation in this area.A simple numerical experiment shows that considering the effect will lead ground temperature to increase on the slope having more sunshine,and vice versa.     

饱和岩石的各向异性及非线性黏弹性响应

在MTS伺服压机上对不同饱和状态的砂岩、大理岩标本进行了垂直层理和平行层理两个方向的正弦波加载试验,研究了饱和岩石的各向异性及非线性黏弹性行为. 在最大载荷低于岩石的屈服点时,获得的衰减、杨氏模量、泊松比、波速都表现出显著的各向异性,同时它们还具有较明显的应变振幅效应和频率效应. 随着应变振幅的增大,衰减近似呈线性增长,杨氏模量和泊松比近似呈线性下降. 在0.005-4Hz频段内除衰减不明显依赖频率以外,杨氏模量、泊松比、波速对频率的依赖性都较强; 当频段扩大到15Hz时,这4个参数都表现出较强的频率效应. 饱和岩石的衰减、杨氏模量、泊松比、波速均随饱和液体的黏滞系数增大而增大.     

2000年4月6日磁暴期间磁扰变化在低纬子午链的纬度效应

利用低纬地磁子午链上H和D分量的分均值数据 ,分析了 2 0 0 0年 4月 6日磁暴期间磁扰变化的纬度效应 .主要特点是 :(1 )急始期间H分量急始跃变幅随磁纬降低而减小 ,且急始变幅的下降率随磁纬降低而逐渐增大 ;(2 )初相期间H分量第 2峰值的变幅和初相持续时间随磁纬降低而减小 ;(3)主相期间H分量迅速减小 ,并随纬度降低最大变幅明显增加 ;(4)恢复相H分量呈两阶段上升趋势 ,前一阶段迅速上升 ,后一阶段上升速度明显减小 .最后对这些磁扰变化的纬度效应与空间电流体系的密切关系作了讨论 .