用隔绝法对极干旱区土壤水分来源的分析

 通常认为极干旱区土壤水分来源于降水、大气或凝结水,深埋区不存在潜水蒸发。然而通过使用拱棚法初步证明在极干旱深埋区存在潜水蒸发,而潜水是土壤水分的重要来源。为了进一步求证土壤水分来源,开挖200 cm×200 cm×200 cm的土坑,完全隔绝与下层土壤及四周的水分联系,回填后监测土壤10、30、50、100、150 cm的空气温湿度;同时设置与四周隔绝但底面联通的对照坑。27 d后都模拟25 mm降雨。监测发现模拟降雨前联通土壤的水分含量、空气相对湿度、绝对湿度都明显高于隔绝土壤。1 a后远离降雨时土壤水分的检测发现隔绝土壤水分含量低于联通对照,但因隔绝土壤处于潜水蒸发漫溢的相同气象环境,其湿度不会无限下降。隔绝对比实验反演证明深埋极干旱区存在潜水蒸发。     

青藏高原冈底斯带中段花岗岩类及其中铁镁质微粒包体地球化学特征

青藏高原冈底斯带花岗岩及其中铁镁质微粒包体地球化学研究表明,冈底斯花岗岩带岩石类型是钙碱性、中铝质的。１０对花岗岩及包体的地球化学分析结果表明,ＳｉＯ２与Ａｌ２Ｏ３、ＣａＯ、ＭｇＯ、ＦｅＯＴ都是呈线性降低的趋势、二元素散点图及共分母图（如Ｌａ－Ｃｅ,Ｓｍ－Ｎｄ,Ｔｈ－Ｌａ,Ｌａ－Ｂａ,Ｔｈ／Ｙｂ－Ｔａ／Ｙｂ,Ｚｒ／Ｙ－Ｚｒ,Ｃｓ－Ｒｂ,ＳｉＯ２－Ｚｒ／ＴｉＯ２）具有不同程度的直线变异关系,而花岗岩及包体的同位素地球化学表明花岗岩中含有大量幔源组分,说明与岩浆混合作用及（或）成分分异有关。花岗岩及包体的常量元素、微量及稀土元素、同位素地球化学特征显示两者具有同源性。     

基于GIS的洪水灾害评估智能决策支持系统设计

针对洪水灾害评估的特点，将地理信息系统（ＧＩＳ）技术与智能决策支持系统结合起来，设计了用于洪水灾害评估的智能决策支持系统，阐述了其设计原理，讨论和分析于基于ＧＩＳ的洪水灾害评估智能决策支持系统的组成模式，给出了其总体设计框架。     

The Wan-An fault and its relationship with the Wan-An Basin, western South China Sea

The Wan An Basin, a major basin located in the southwestern part of the South China Sea, is suggested to be closely related to the extrusion of the Indo-China Block. But the published documentation about the Wan An Basin is very sparse. High-resolution seismic reflection profiles obtained by the petroleum industry along the southwestern margin of the South China Sea provide us a chance to study the characteristics of the Wan-An fault and its relationship to the Wan-An Basin. The Wan-An Fault staggered strata in the Wan-An Basin and formed negative flower structures. The deformation related to the Wan-An fault is localized along the fault, while the strata away from the strike-slip fault were not affected. The characteristics of strike-slip extensional basin are not obvious in the Wan-An Basin. However, this basin has obvious characteristics of rift basin. Initial analysis shows that the Wan-An Basin should be a continental margin rift basin.     

遗传算法在确定震源位置中的应用

地震定位需要震源的空间坐标和发震时刻，可以通过使观测走时和计算走时的拟合差达到最小来实现。遗传算法是解决此最优化问题的有效方法。本文对遗传算法确定震源位置的基本思路思路进行了说明和分析，讨论了拟合差随迭代次数的分布特征，最后，给出了最优化过程搜索震源位置在四维空间的分布。     

Fractal models for estimating local reserves with different mineralization qualities and spatial variations

The concentration-area model, one of the widely applied fractal models, is utilized to describe the spatial distribution of mineralization variables, i.e., orebody thickness and grade-thickness. And based on the concentration-area model, a new fractal model for reserve estimation (abbreviated as FMRE-CA) is established. Via the demarcation values obtained in the concentration-area model, the orebody is spatially divided into several parts with different value ranges and spatial variation of mineralization variable. Based on the FMRE-CA, the local ore reserves in the parts are estimated, and the global reserve is obtained by addition of the local reserves. In the FMRE-CA, the spatial variation of the mineralization variable in a local reserve is characterized by a fractal dimension, and a greater fractal dimension denotes a more variation. Compared to traditional reserve estimations based on discrete and linear functions, the FMRE-CA is established via continuous and nonlinear function, and it is easier in calculation process and different in the way in which the local reserves are delimitated. Compared to another fractal model for reserve estimation based on number-size model (abbreviated as FMRE-NS), the FMRE-CA is capable of estimating the local reserves. A gold orebody in Southwest Yunnan and two bauxite orebodies in Western Guangxi, China, are selected for case study. In the case study, the global reserve calculated via the FMRE-CA and those derived from the FMRE-NS and traditional geometric block method are analogous.     

准噶尔盆地玛湖凹陷下二叠统风城组含碱层段韵律特征及成因*

准噶尔盆地玛湖凹陷早二叠世风城组沉积时期为典型的碳酸盐型咸化湖盆,湖盆咸化过程中析出大量的碱矿(钠碳酸盐类矿物)。通过含碱层段主量元素、碳氧同位素分析,结合岩心宏观及微观矿物岩石特征,探讨了含碱层段韵律特征及形成机理。研究层段碱矿与沉凝灰岩互层,形成明暗相间的咸化韵律。浅色碱矿层质地较纯,主要为苏打和小苏打,主量元素表现为 Na₂O含量高,CaO、MgO、SiO₂和Al₂O₃含量低;暗色层段主要为含斑点状碳钠钙石的沉凝灰岩,主量元素表现为Na₂O含量低,CaO、MgO、SiO₂和Al₂O₃含量高。浅色碱矿层和暗色沉凝灰岩段碳氧同位素值均为正,表明其沉积水体具高盐度特征。浅色含碱层段具有更高的 δ¹⁸O 值,反映了碱矿层沉积时期强烈蒸发的气候条件。根据δ¹⁸O/δ¹³C值的波动将研究层段划分为炎热干旱和相对湿润的气候条件,并据此解释不同韵律层盐类矿物形成机理。暗色的沉凝灰岩沉积代表地表流水注入量大于蒸发量,沉凝灰岩中盐类矿物含量少或者呈斑点状从颗粒间的卤水中析出;随着蒸发量的增高以及古气候由温暖潮湿转变为干旱炎热,地表流水注入量急剧减少,强烈蒸发控制了碱矿的沉积,形成浅色质地较纯的碱矿层。气候的频繁交替形成了风二段碱矿与沉凝灰岩频繁互层的特征。     

GPS事后相位差分坐标解算模型及其相关问题的研究

在GPS事后相位差分定位模式中,基线处理的数学模型和整周模糊度的正确解算直接影响了坐标成果所能达到的精度指标。以土地资源调查和交通工程测量为工程实际应用背景,重点对GPS事后RTK坐标解算模型、GPS外业观测时间的合理确定和GPS工程控制网投影变形的处理三个方面进行了较为深入的研究。观测值权的确定是基线坐标解算过程所遇到的主要技术难点之一,在分析常规定权方法的基础上提出了“高度角定权法”,并以某大型水电站的实测数据分析了三种定权方法对基线坐标解算结果精度的影响,数据结果清楚地表明本文提出的“高度角定权”能有…     

Resilience to natural hazards: a geographic perspective

Resilience is increasingly used as an approach for understanding the dynamics of natural disaster systems. This article presents the origin of resilience and provides an overview of its development to date, which draws on the wide literature on ecological science, social science, social–environmental system and natural hazards. From a geographic perspective, the model of disaster resilience of “Loss–Response” of Location (DRLRL) was created and disaster resilience was defined from three dimensional mode, which focused on the spatial, temporal scale of resilience and attributes of hazard-affected bodies. A geographic approach was put forward to measure the disaster resilience, including two properties of inherent resilience and adaptive resilience and a case study was implemented in order to validate this approach. This perspective would offer greater potential in application of resilience concept, especially in the process of integrated risk management and disaster recovery.