喀斯特区域的水化学不稳定性——以黔中地区为例

黔中地区是岩溶作用发育的喀斯特区域.1993年秋和1994年春末采自该地区不同类型水样的水化学分析表明:碳酸盐岩裂隙泉水呈中偏碱性,为[C]Ca-Ⅱ型;秋季离子总量、HCO₃-及Ca2+浓度大于春季.裂隙泉水流经地表一定距离后,HCO₃-降低,pH及SO₄2-、Cl-、K+、Na+明显增高.黄果树的天星桥、水帘洞及落水潭三个部位河水的SO₄2-、Na+以及Fe3+、NO₃-等浓度的季节性变化也更加明显.春季因瀑布暴气,CO₂的逸出,钙华生成更强烈一些.红枫湖作为喀斯特区域地表水的汇集地,HCO₃-与SO₄2-的当量比值仅2.1～2.4;Ca2+与Mg2+比值上升为2.4～4.2,Cl-浓度较碳酸盐岩裂隙泉水增高1倍;Na+浓度增高一个数量级.说明流域内地表土层溶蚀及人为污染影响的增强.土层孔隙水属强矿化水,而湖水呈现过渡特征.碳酸盐沉淀作用、硫酸盐矿化作用及固氮氨化作用,导致水质组成的显着差异.     

浅探兰州市城区大气环境污染与治理的若干问题

介绍了兰州市城区大气污染的物理机制和客观成因,总结了目前正在采用或论证的一些治理措施和方法,并对这些进行了分析与讨论,提出了今后应重点研究的几个问题,最后对兰州市城区大气污染的治理提出了一些初步看法与建议。     

河西内陆河春季流量变化特征的分析和预测

利用昌马、莺落峡、九条岭３个水文站四十余年的月平均流量资料,分析河西地区３条主要内陆河春季流量的长期变化特征,并用均生函数模型对流量进行了预报,为河西地区水资源的研究和利用提供参考依据     

Central Europe: Active or residual tectonic stresses

The regional stress field in the Western Alps and their northern foreland has been investigated byin situ stress determinations. More than 600 strain relief measurements were made with resistance strain gages in boreholes carried out in mines, tunnels and quarries. The stresses calculated and data obtained from other papers were used to get a detailed idea of the stress conditions in Central Europe.The measurements confirm a continuous flux of compressive stress from the Alps to the northern foreland east of the Rhinegraben. The largest stresses are observed in the Central Alps, the lowest in the Rhinegraben rift system. The horizontal stresses exceed at nearly all places the vertical ones. Evidently the excess of horizontal stress is generated by active plate tectonics in the Alps. A tectonic model to explain the observed stress pattern is presented.     

MHD instability due to non-homogeneity and non-uniformity of magnetic field in gravitating medium and its consequences in the central region of galaxies

The MHD wave instabilities due to non-uniform magnetic field and non-homogeneity of density have been studied. The reference (coordinate) system considered here is cylindrical type. The General Dispersion Relation (GDR) for the wave propagation in a gravitating but non-relativistic region has been derived. Similar to common knowledge, the said non-uniformities have been found to be responsible for the instability of the system. But interestingly many instability factors are produced due to presence of two types of non-uniformities simultaneously. This theory may add more clues for the event of instabilities, formation of hot plasma-bed in Galactic Central Region, and mass out-flow from there. Many conditions for instabilities could be obtained from GDR deduced here. However, a few conditions for critical wavelength of the MHD wave have been obtained in terms of system parameters (like gradient of magnetic field and rotation). This theory, in turn, may be helpful for the better understanding of the Explosion Theory of formation of outer structure of Galaxies like ours.     

Connections Between Different Types of El Ni~no and Southern/Northern Oscillation

It has long been acknowledged that there are two types of El Ni(n)o events,i.e.,the eastern Pacific El Ni(n)o (EE) and the central Pacific El Ni(n)o (CE),according to the initial position of the anomalous warm water and its propagation direction.In this paper,the oceanic and atmospheric evolutions and the possible mechanisms of the two types of El Ni(n)o events were examined.It is found that all the El Ni(n)o events,CE or EE,could be attributed to the joint impacts of the eastward advection of warm water from the western Pacific warm pool (WPWP) and the local warming in the equatorial eastern Pacific.Before the occurrence of CE events,WPWP had long been in a state of being anomalous warm,so the strength of eastward advection of warm water was much stronger than that of EE,which played a major role in the formation of CE.While for the EE events,most contribution came from the local warming of the equatorial eastern Pacific.It is further identified that the immediate cause leading to the difference of the two types of El Ni(n)o events was the asynchronous variations of the Southern Oscillation (SO) and the Northern Oscillation (NO) as defined by Chen in 1984.When the transition from the positive phase of the NO (NO+) to NO- was prior to that from SO+ to SO-,there would be eastward propagation of westerly anomalies from the tropical western Pacific induced by NO and hence the growth of warm sea surface temperature anomalies in WPWP and its eastward propagation.This was followed by lagged SO-induced weakening of southeast trade winds and local warming in the equatorial eastern Pacific.These were conducive to the occurrence of the CE.On the contrary,the transition from SO+ to SO- leading the transition of NO would favor the occurrence of EE type events.     

琼东南盆地深水区中央峡谷黄流组物源特征

物源分析作为岩相-古地理研究的前提和基础,物源体系决定了砂体的展布和储集性能。为明确中央峡谷体系黄流组储集体展布规律及下一步勘探方向,本文应用中央峡谷最新钻井资料,采用重矿物组合、锆石U-Pb测年等分析方法,结合地震反射特征,对中央峡谷黄流组物源体系特征进行分析。地震反射特征表明来自海南隆起和昆嵩隆起物源的三角洲体系,通过二次搬运沉积了陆架斜坡区和盆底的低位海底扇,为中央峡谷的沉积充填提供了充足的粗碎屑沉积物;新钻井黄流组样品中重矿物组合以白钛矿、石榴石、磁铁矿含量较高为主要特征,与莺歌海盆地受蓝江物源影响和琼东南盆地受丽水-秋滨河物源影响的地层重矿物组合相似;锆石U-Pb测年分析表明,中央峡谷黄流组地层中样品年龄图谱具有30~2 000Ma变化范围,与莺歌海盆地受昆嵩隆起物源影响的钻井以及越南现代河流采集的沙样具有非常一致的年龄段和丰度。综上所述,中央峡谷受多物源的影响,越南昆嵩隆起为主的琼东南盆地西部物源体系,是琼东南盆地乐东凹陷晚中新世深水扇以及中央峡谷粗碎屑物质的主要沉积物供给来源区。     

北极中央区海冰密集度与云量相关性分析

本文使用海冰密集度以及低云、中云、高云的日平均数据,借助滑动相关分析方法,研究了北极中央区海冰密集度与云量之间的相关性,分析了海冰与云的相互作用机制。研究表明,在春季海冰融化季节(4、5月)、秋季海冰冻结季节(10、11月),低云与海冰密集度之间表现为较好的负相关,表明在这段时间内冰区海面蒸发强烈,对低云的形成有重要贡献。在10月和11月,中云与海冰密集度也有很好的负相关,表明秋季低云可以通过抬升形成中云。高云与海冰密集度之间并没有明显的相关性,可能原因:一方面海冰的空间分布对高云无影响,另一方面,高云主要影响到达的短波辐射,从而影响海冰的融化和冻结速度,与海冰厚度有直接显著的关系,而与海冰密集度的关系不明显。此外,在海冰密集度与低云存在较好负相关的情况下会出现某些年份相关性不好的情况,我们的研究发现这是北极中央区与周边海区发生了海冰交换或云交换的结果。     

基于空间圆模型的隧道全局中轴线提取方法

隧道中轴线不仅能够检核隧道竣工测量,而且在隧道变形监测中其精度直接影响横断面提取的准确性。本文提出一种精确提取隧道全局中轴线的方法:首先将隧道三维点云投影至水平面形成平面点云,并采用Delaunay三角网算法获取点云边界;其次利用点云边界中转折点间的距离与隧道直径的关系提取出隧道边界线;然后依据隧道边界和中心的几何关系提取出水平中轴线,并以此提取隧道横断面;最后对隧道横断面进行空间圆模型拟合生成隧道中轴线。通过实验分析,本文方法能够适应于长距离、弯曲型隧道,为隧道中轴线提取研究提供借鉴依据。     

喜马拉雅造山带中段亚东地区石榴角闪岩的成因：岩石学和锆石U- Pb年代学

喜马拉雅造山带中段出露的基性麻粒岩是理解印度大陆前喜马拉雅期演化历史和新生代碰撞造山作用的理想研究对象。本文对亚东多庆湖地区的石榴角闪岩进行了岩石学、全岩主微量元素地球化学和锆石U- Pb年代学研究,揭示了其原岩类型和新生代的变质作用过程。石榴角闪岩的原岩很可能为新元古代(~890 Ma)的玄武岩,具有E- MORB型岩石的地球化学特征。石榴角闪岩具有三期矿物组合：① 进变质矿物组合可能为石榴子石+角闪石+斜长石+钛铁矿+石英,即石榴子石核部及其中包裹体;② 峰期矿物组合为石榴子石+角闪石+斜长石+黑云母+石英,即石榴子石边部和基质矿物;③ 退变质矿物组合为角闪石+斜方辉石+斜长石+黑云母+石英,包括退变质域和石榴子石边部的后成合晶矿物。矿物温压计和相平衡模拟表明,石榴角闪岩进变质、峰期和退变质条件分别为609~621℃和0. 59~0. 65 GPa、805~845℃和0. 91~1. 04 GPa、825~840℃和0. 61~0. 68 GPa,经历了峰期高压麻粒岩相的变质作用。锆石U- Pb年代学研究表明,石榴角闪岩的峰期变质时间为34. 8~20. 3 Ma,退变质时间为18. 1~17. 7 Ma,可能经历了一个较长期的部分熔融过程。本文研究认为,亚东石榴角闪岩是印度板块向欧亚板块长期俯冲、地壳增厚成因的基性麻粒岩,原岩可能与Rodinia超大陆拼合相关;其以加热埋藏、近等温降压为特征的顺时针P- T轨迹指示了喜马拉雅造山带中段的大喜马拉雅岩系上部构造层位经历了长期持续的地壳增厚和高温麻粒岩相变质作用,以及早中新世(21~17 Ma)相对快速的减压抬升和随后(17 Ma之后)相对缓慢的折返至地表的演化过程。