"三联式"资源定量预测与评价--数字找矿理论与实践探讨

随着信息技术的发展,矿产勘查已步入数字化,定量化研究的新阶段。“三联式”成矿预测及资源评价途径正是“数字找矿”的创新探索。“三联式”成矿预测以地质异常分析为基础,以成矿多样性分析与矿床谱系研究为指导,将地质异常,成矿多样性及矿床谱系三方面定量化研究紧密结合形成矿产预测及定量评价的有机切入点,是实现全面数字找矿的必由之路,也是矿产勘查评价领域应用信息技术的基础和前提。     

Early Mesozoic mantle-crust transitional zone in eastern Inner Mongolia: Evidence from measurements of compressional velocities of xenoliths at high pressure and high temperature

Compression wave velocityV _p has been measured on 10 representative rock samples from the Early Mesozoic granulite and mafic-ultramafic cumulate xenoliths population from the Harqin area of the Inner Mongolia Autonomous Region (for short Inner Mongolia) as an aid to interpretingin-situ seismic velocity data and investigating velocity variation with depth in a mafic lower crust. The experiments have been carried out at constant confining pressures up to 1 000 MPa and temperatures ranging from 20 to around 1 300°C, using the ultrasonic transmission technique. After corrections for estimatedin situ crustal pressures and temperatures, elastic wave velocities range from 6.5 to 7.4 km·s^?1, indicating that they are components of the Early Mesozoic crust-mantle transitional zone. Combining with previous experimental data, we have also reestablished the Early-Mesozoic continental compression velocity profile and compared it with those of the present and of the different tectonic environments in the world. The result shows that it is similar to the velocity pattern of the extensional tectonic area, providing new clues to the Mesozoic continental structure of the North China Craton.     

A bed‐load transport model for rough turbulent open‐channel flows on plane beds

Data from flume studies are used to develop a model for predicting bed‐load transport rates in rough turbulent two‐dimensional open‐channel flows moving well sorted non‐cohesive sediments over plane mobile beds. The object is not to predict transport rates in natural channel flows but rather to provide a standard against which measured bed‐load transport rates influenced by factors such as bed forms, bed armouring, or limited sediment availability may be compared in order to assess the impact of these factors on bed‐load transport rates. The model is based on a revised version of Bagnold's basic energy equation i_bs_b = e_bω, where i_b is the immersed bed‐load transport rate, ω is flow power per unit area, e_b is the efficiency coefficient, and s_b is the stress coefficient defined as the ratio of the tangential bed shear stress caused by grain collisions and fluid drag to the immersed weight of the bed load. Expressions are developed for s_b and e_b in terms of G, a normalized measure of sediment transport stage, and these expressions are substituted into the revised energy equation to obtain the bed‐load transport equation i_b = ω G ^3·4. This equation applies regardless of the mode of bed‐load transport (i.e. saltation or sheet flow) and reduces to i_b = ω where G approaches 1 in the sheet‐flow regime. That i_b = ω does not mean that all the available power is dissipated in transporting the bed load. Rather, it reflects the fact that i_b is a transport rate that must be multiplied by s_b to become a work rate before it can be compared with ω. It follows that the proportion of ω that is dissipated in the transport of bed load is i_bs_b/ω, which is approximately 0·6 when i_b = ω. It is suggested that this remarkably high transport efficiency is achieved in sheet flow (1) because the ratio of grain‐to‐grain to grain‐to‐bed collisions increases with bed shear stress, and (2) because on average much more momentum is lost in a grain‐to‐bed collision than in a grain‐to‐grain one. Copyright © 2006 John Wiley & Sons, Ltd.     

Approximate incremental dynamic analysis using the modal pushover analysis procedure

Incremental dynamic analysis (IDA)—a procedure developed for accurate estimation of seismic demand and capacity of structures—requires non‐linear response history analysis of the structure for an ensemble of ground motions, each scaled to many intensity levels, selected to cover the entire range of structural response—all the way from elastic behaviour to global dynamic instability. Recognizing that IDA of practical structures is computationally extremely demanding, an approximate procedure based on the modal pushover analysis procedure is developed. Presented are the IDA curves and limit state capacities for the SAC‐Los Angeles 3‐, 9‐, and 20‐storey buildings computed by the exact and approximate procedures for an ensemble of 20 ground motions. These results demonstrate that the MPA‐based approximate procedure reduces the computational effort by a factor of 30 (for the 9‐storey building), at the same time providing results to a useful degree of accuracy over the entire range of responses—all the way from elastic behaviour to global dynamic instability—provided a proper hysteretic model is selected for modal SDF systems. The accuracy of the approximate procedure does not deteriorate for 9‐ and 20‐storey buildings, although their dynamics is more complex, involving several ‘modes’ of vibration. For all three buildings, the accuracy of the MPA‐based approximate procedure is also satisfactory for estimating the structural capacities for the limit states of immediate occupancy, collapse prevention, and global dynamic instability. Copyright © 2006 John Wiley & Sons, Ltd.     

A Statistical Investigation of the Earthquake Predictions Using LURR

In terms of the spatial scanning of LURR (Load-Unload Response Ratio), we have been predicting the seismic tendency within the next year for the mainland of China from 1995 to 2003. In order to make the quantitative retrospective assessment of LURR method, we compare the results with Poisson null hypothesis. The results show that the prediction by LURR method is much better than Poisson hypothesis.     

内蒙古沙麦岩体：正εNd（t）值的过铝质花岗岩

内蒙古沙麦岩体位于大兴安岭中段西坡,是二连浩特-东乌珠穆沁旗花岗岩带的重要组成部分。岩体中脉岩和围岩捕虏体较为发育,岩性组合主要为中细粒黑云母花岗岩和细粒似斑状花岗岩。在化学成分上,沙麦岩体以铝弱过饱和,富硅,全碱含量中等和低磷为特点,标准矿物中刚玉分子大于1%,可归为过铝质 S 型花岗岩。在稀土元素和微量元素组成上,岩体富 Rb、Th、U、Ta,贫 Ba、Sr、P、Ti,Rb/Sr 比值高,K/Rb 比值低,Eu 负异常明显。在 Nd 同位素组成上,岩体 Nd 同位素组成变化较大,除一件样品ε_(Nd)(t)值为负值以外,普遍以具正ε_(Nd)(t)值为特点,T_(2DM)值介于275.79～1048.41Ma 之间。研究结果表明,沙麦岩体形成于晚中生代后造山的岩石圈伸展环境中,是幔源基性岩浆底侵及其诱发的壳-幔混合岩浆,同化中上地壳泥质围岩并经高程度分离结晶的产物。     

江西德兴斑岩铜矿成矿物质来源同位素示踪

德兴斑岩铜矿铜厂和富家坞矿区样品中碳、硅、铜等同位素的分析研究表明:含矿菱铁矿中碳同位素δ13CPDB值近似于原始岩浆初始值;代表成矿同期样品的硅同位素组成δ30Si分布范围与该区岩浆岩的硅同位素组成相近,个别样品偏离代表岩浆岩的δ30Si分布范围;岩体中65Cu的早成矿阶段团块状黄铜矿铜同位素组成相对较高,而晚成矿阶段脉状黄铜矿铜同位素组成相对较低。结合前人硫同位素数据可知:德兴铜矿成矿物质主要来自花岗闪长斑岩岩体,少部分来自围岩。     

基于多源卫星图像融合的水坝检测方法的研究

本文提出了一种基于多源卫星图像融合的水坝检测方法，该方法在特征级融合的模式下，利用多源卫星图像特征信息互补的优势，先后提取多个卫星图像中目标的特征信息，再通过多传感器数据融合方法中的逻辑模板法对特征进行融合，得到系统的目标结果输出。试验结果显示，该算法能在大幅复杂背景下有效地对水坝进行检测并定位，并减少了单源卫星图像进行目标检测的错判、误判率。整个算法能完全实现自动检测，可达到预想的目的。     

一个针对ASTER数据同时反演地表温度和比辐射率的四通道算法

本文利用对地观测卫星多传感器的特点，提出了针对ASTER数据同时反演地表温度和比辐射率的多通道算法。即利用ASTER数据的第11，12，13，14热红外波段建立热辐射传输方程，并通过对于地表比辐射率分析可知，ASTER4个热红外波段的比辐射率可以用近似线性方程表示，得到了6个方程6个未知数，从而形成了针对ASTER数据的同时反演地表温度和比辐射率的多通道算法。对于关键参数大气透过率，则是通过同一颗星的MODIS传感器的3个近红外波段反演大气水汽含量，然后用MODTRAN模拟大气水汽含量与ASTER热红外波段的统计关系，并进而根据这二关系来计算ASTER热红外波段的大气透过率。由于MODIS和ASTER是在同一颗星上。因此这种大气透过率估计方法保证了地表温度反演过程中所需大气参数的同步获取。     

区域降水数值预报产品人工神经网络释用预报研究

利用T213、日本细网格降水预报等数值预报产品,采用人工神经网络方法进行预报释用。通过聚类分析方法对广西自治区测站进行分类,简化预报对象,对数量众多的T213数值预报产品采用自然正交分解(EOF)方法,浓缩大量因子的有效信息,并结合日本降水预报因子建立广西5~6月区域降水量级的逐日人工神经网络预报模型。运用与实际业务预报相同的方法进行逐日预报试验。结果表明,用这种数值预报产品释用方法建立广西3个预报区域的B-P人工神经网络预报模型对中雨以上降水量级预报的TS评分分别为0.55、0.5和0.26,比目前业务预报中参考使用的T213和日本数值预报产品降水预报具有更好的预报效果。