无定河流域全新世中期人类聚落选址的空间分析及地貌环境意义

以无定河流域的数字高程模型为主要研究对象,利用地理信息系统软件进行空间分析,与陕西北部无定河流域龙山时期遗址的分布位置叠置和聚类分析,讨论聚落选址与地貌类型、距河流水平距离、河网等级等6个地形地貌因子之间的关系。结果发现,全新世中期无定河流域人类在聚落选址时,对水文条件、地貌和地面坡度条件有较强的倾向性,而对地面朝向无明显倾向性。选址时选择地形地貌影响因子的优先顺序为:地貌类型、遗址距河流距离、遗址处地面坡度、遗址处河流等级、遗址处地面朝向。     

辽宁后仙峪硼矿区古元古代电气石岩: 锆石特征及SHRIMP定年

为了确定辽东硼矿含硼岩系中电气石岩的形成时代, 对后仙峪硼矿区电气石岩首次进行了锆石SHRIMP U-Pb年龄测定.阴极发光图像显示, 锆石具核-边结构, 锆石核部多具振荡环带, 为高Th/U值的岩浆碎屑锆石; 锆石边部无明显结构变化, 为变质成因.岩浆碎屑锆石和变质锆石的年龄分别为2 171~2 175 Ma和1 894~1 906 Ma.结合野外地质和岩相学研究, 认为后仙峪硼矿区电气石岩原岩为古元古代克拉通裂谷环境中源于地壳再循环组分混染的亏损地幔的中酸性岩浆活动引发海底喷流作用的产物, 其原岩形成时代为古元古代中期(2 171~2 175 Ma), 并在稍后(1 894~1 906 Ma)遭受变质作用叠加改造.      

SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.282615 to 0.282657, with εHf(t) values of 5.02±0.28, indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.     

Statistics of gravity wave spectra in the troposphere and lower stratosphere over Beijing

We utilize the temperature profiles with a height resolution of 50-m obtained over the Beijing Observatory in the period between January of 2002 and December of 2002 to study vertical wavenumber spectra of normalized temperature fluctuations in the 1.67-8.02 km and 13.57-19.92 km altitude ranges and compare them with linear saturation model.Results indicate that individual vertical wavenumber spectra reveal a considerable variability in both slope and amplitude.The observed variability is not consistent wit...     

巽他海峡BAR9442岩心30 kaBP以来的沉积记录与古季风活动

为重建巽他海峡区古季风活动历史,通过对BAR9442岩心氧同位素、AMS14C测年、陆源碎屑标准偏差区间粒径分布,以及上升流种Globigerina bulloides等变化特点分析,并结合前人对该岩心粘土矿物的研究,获得如下认识:末次冰期30~17 kaBP,海平面下降,陆源粉砂物质输入增加; 南半球夏季日照率高,然而受冰期热带辐聚带位置影响,西北季风受阻,东南信风持续吹过研究海域形成类似东南季风的效应,气候冷干; 受印度东北季风影响,伊利石含量最高,上升流活动不发育, 古生产力降低.17~8 kaBP,海平面迅速上升,出现较强的表层穿越流活动,粘土物质成为沉积物的主要组分; 此时东南与西北季风都有增强,说明当时研究区气候有着更强的季节性.全新世8 kaBP以来,全球海平面上升使穿越流活动加强,沉积物粘土组分含量最大,西北季风带来温暖湿润的气候条件.      

地上下一体化的三维空间数据库模型设计与应用

大规模地上、地下三维实体建模与空间分析应用中,由于三维模型的多样性和对象空间分布的不均衡性,如何高效地一体化组织和管理海量三维空间数据成为当前三维GIS的核心问题之一.提出了一种兼顾空间关系与语义关系的三维空间数据库模型,给出了相应的概念模型、逻辑模型和物理模型.特别针对地质体的复杂性,给出了顾及语义的多尺度地下空间目标概念模型和多层次三维空间索引机制.用武汉市和南京市三维数字城市示范区模型数据进行了应用试验分析,验证了该模型的有效性.      

新疆和田玉岩石学特征及其扫描电镜研究

新疆和田玉产于塔里木盆地之南昆仑山的变质软玉矿床, 该矿床是由镁质大理岩与中酸性岩浆岩接触交代而形成。通过对和田玉的岩石矿物学研究表明和田玉主要由富钙富镁的透闪石矿物构成,其化学组分中Ｍｇ２＋ ／（Ｍｇ２＋ ＋ Ｆｅ２＋ ）比值均大于０．９。对和田玉岩石薄片镜下观察发现,和田玉是由透闪石微晶－隐晶质集合体构成,其颗粒越细小, 交织结构越致密,其质地就越细腻润泽。通过对和田玉的扫描电镜的观察分析, 探讨了和田玉高韧度主要与其特殊的交织结构所产生的粒间绞合力有关     

On the Relationship Between the Crustal Strain Rate and Seismicity:Detect the Source-Field Relation from the Crustal Strain Field

The relationship between the strain cumulative rate (i.e., the crustal strain rate, or CSR in short) and seismic activity is analyzed to develop a new method to determine risky regions for strong shocks within recent years by the recorded crustal strain field. Seismic activity, especially the recurrence period, is different in different areas. Ding Guoyu (1984) pointed out that, for different seismic regions, the difference in the recurrence period of strong earthquakes is mainly controlled by their difference in the rate of the tectonic movement, which is controlled by the seismogenic environment and the tectonic conditions. The method of determining the risky regions for strong shocks from the gradient of vertical strain rates observed in a geodetic survey is preliminarily tested with the earthquakes in recent years; the results show that this method is effective and useful for earthquake prediction. The relationship between CSR and seismicity in a specific region is studied with strain theories, obse