遥感技术在邹城市地壳稳定性评价中的应用

根据线性构造的影像特征,利用多种计算机图像处理方法提取邹城市线性构造信息,共解译出5组不同走向的线性构造,并且对其相对活动关系进行了分析。在此基础上,结合地震资料对该市所属地区的地壳稳定性进行了评价,认为南北向线性构造和北西向线性构造为主要的控震构造,并且圈定了一些地壳稳定性较差的地段,从而为邹城市的城乡发展规划和工农业建设等各项工作提供了重要依据。      

Enhancing Geological Understanding and Identifying Gold Anomalies in the Ailaoshan Orogen

The Ailaoshan Orogen in the southeastern Tibet Plateau, situated between the Yangtze and Simao blocks, underwent a complex structural, magmatic, and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental concentrations. These elements can conceal or reduce anomalies due to the mutual effect between different anomaly areas. Dividing the whole zone into subzones based on tectonic settings, ore cluster areas, or sample catchment basins (Scb), geochemical and structural anomalies associated with gold (Au) mineralization have been identified utilizing mean plus twice standard deviations (Mean + 2STD), factor analysis (FA), concentration-area (C-A) modeling of stream sediment geochemical data, and lineament density in both the Ailaoshan Orogen and the individual subzones. The FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types, identify specific element associations of known rocks and discern the porphyry or skarn-type Au mineralization. Compared with methods of Mean + 2STD and C-A model of data in the whole orogen, which mistake the anomalies as background or act the background as anomalies, the combined methods of FA and C-A in the separate subzones or Scbs works well in regional metallogenic potential analysis. Mapping of lineament densities with a 10-km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium-high lineament density. In contrast, the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density, consistent with the locations of known Au deposits. By analyzing the map of faults and Au anomalies, two potential prospecting targets, Scbs 1 and 63 with a sandstone as a potential host rock for Au, have been identified in the Ailaoshan Orogen. The use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying mineralization anomalies associated with Au, rather than analyzing the entire large area.     

Artificial Lineaments in Digital Terrain Modelling: Can Operators of Topographic Variables Cause Them?

Digital terrain modeling is widely used in geological studies. In some cases, orthogonal and diagonal linear patterns appear on maps of local topographic variables. These patterns may be both portrayals of geological structures and artefacts. Some researchers speculated that possible anisotropy of operators of local topographic variables might be a cause of these artefacts. Using a principle for testing derivative operators in image processing, we gave proof to isotropy (rotation invariability) of operators of a majority of local topographic attributes of the complete system of curvatures (i.e., slope gradient, horizontal curvature, vertical curvature, mean curvature, Gaussian curvature, accumulation curvature, ring curvature, unsphericity curvature, difference curvature, minimum curvature, maximum curvature, horizontal excess curvature, and vertical excess curvature). Rotating an elevation function about z-axis and then applying these operators cannot lead to variations in both values of the topographic variables and patterns in their maps, comparing with results of applying these operators to an unrotated elevation function. This demonstrates that linear artefacts with preferable directions in maps of the topographic attributes specified cannot be caused by intrinsic properties of their operators. Other possible sources for false linear patterns in maps of topographic variables are briefly discussed: (a) errors in the compilation of digital elevation models (DEMs), (b) grid geometry of digital terrain models (DTMs), (c) errors in DEM interpolation, (d) imperfection of algorithms for DTM derivation, and (e) aliasing errors.     

西藏仲巴县穷果北部日喀则弧前盆地地层再认识

通过对区内发育完好并保留下来的白垩纪—始新世地层的研究，海相白垩纪日喀则群自下而上可划分为昂仁组、帕达那组、曲贝亚组；古新世—始新世错江顶群包括下部曲下组和上部加拉孜组，整合覆于错江顶群之上的“如角藏布砂砾岩”为弧前盆地封盆粗碎屑岩。日喀则群与错江顶群在沉积学、地层古生物学及构造地质学诸方面的差异揭示了两群之间，更确切地说，曲贝亚组与曲下组之间呈不整合接触，该不整合形成于坎潘期—马斯特里赫特期与丹尼期之间。该区日喀则弧前盆地完整的地层序列全面再现了印度板块向欧亚板块俯冲过程，两板块的碰撞和新特提斯洋的彻底关闭发生在弧前盆地封盆粗碎屑岩沉积结束以后，这比原来认识的要晚些。     

柴达木盆地北缘煤田构造特征的遥感解译

柴达木盆地北缘地区构造复杂,特征明显。在经过增强处理的ETM卫星遥感图像上,通过详细分析构造判别标志,对研究区线性构造进行解译,并对解译结果进行分区统计分析。线性构造走向玫瑰花图统计表明,构造走向在东、中、西部构造分区内呈现明显的规律性：西部地区断层发育较为复杂,中部地区断裂发育中等,东部地区断层发育比较单一,呈现过渡带性质。构造密度等值线图显示,线性构造总体展布呈北西—南东向,与区域主干构造线方向一致,等值线图清楚的展示出断层发育的“南北分带、东西分块”的特征。     

北京西山周口店地区的线性构造分析

本文阐述了遥感影象线性构造在研究区域构造和深层构造中的地质意义,探讨线性构造与区域构造轮廓间的关系。地壳的构造变形常以丰富的构造地貌景观和线性构造信息显示在遥感图象上。这种深部构造信息也有可能通过地壳的动力变形和深部地球化学反应传递到地表。文中详述了这些线性构造和深层构造及岩浆涌动构造间的内在联系。     

华北克拉通重力梯度带两侧晚中生代火山岩地球化学特征对比研究及其对岩石圈减薄的时空制约

对华北克拉通重力梯度带东西两侧的河北承德袁家庄和内蒙古四子王旗白脑包出露的晚中生代火山岩进行了地球化
学对比研究。全岩主量元素、微量元素和Sr-Nd-Hf同位素数据表明,袁家庄火山岩和白脑包火山岩具有相似的地球化学特
征。这些火山岩轻、重稀土强烈分异,富集大离子亲石元素(如Rb,Ba,Th,U,K等),亏损高场强元素(如Nb,Ta,Zr,
Hf,Ti等);其同位素具有高(87Sr/86Sr)i,低εNd(t)和低εHf(t)的特征,因此认为袁家庄和白脑包火山岩具有相似的源区,即均来
源于被交代的古老岩石圈地幔的部分熔融。结合文献资料,作者认为,这些晚中生代火山岩是华北克拉通岩石圈减薄的直
接产物,中生代时期华北克拉通岩石圈的减薄不仅仅局限于重力梯度带以东地区,以西的部分地区也有发生。 chengxu       

遥感卫星图像中线性地质特征的自动提取

从卫星遥感图像上识别和提取与地质构造有关的线性特征是遥感技术在第四纪地质学中的一个很重要的应用方向。现有的遥感技术多采用单波段遥感图像,提取的线性特征研究开发的一种线性特征网络提取和分析系统,称为ＬＩＮＤＡ系统。结果表明,多波段线性特征提取方法比已有的单波段方法得到了更为满意的线性特征结果。     

湘东南印支运动变形特征研究

关于华南中三叠世晚期印支运动变形特征,一种观点强调其重要性或认为其形成了NNE向为主的上古生界盖层褶皱;另一种观点则认为印支运动强度不大,上古生界NNE向主体褶皱形成于燕山运动甚至更晚。鉴于此,本文重点对湘东南印支运动的构造线走向展开了研究,厘定其为NNE向,反映区域NWW向挤压作用。对资兴三都、宜章瑶岗仙、桂东沙田等晚三叠世—侏罗纪残留盆地进行的研究表明,早燕山构造层下伏不整合面切割了上古生界中NNE向褶皱;以NNE走向为轴将不整合面旋转至水平,恢复上古生界岩层走向及构造线方向为NNE向。不整合面之下的地层层位普遍存在沿东西方向的快速变化。以上表明湘东南印支运动构造线为NNE向而非EW向,区域挤压应力方向为NWW向而非SN向。其动力机制可能与扬子和华夏板块之间产生陆内汇聚有关。结合区域资料,认为印支运动中华南不同地区的构造背景及构造体制存在显著差异。     

新疆伊犁吐拉苏地区的线性构造及控矿特征

采用多种数值图像进行线性构造解译，其中DEM和NOAA主要用于区域尺度，TM用于勘探区尺度，地面磁法数据用于靶区范围的解译分析。研究认为该区线性构造与金矿床的空间分布关系密切，表现为：（1）区域尺度的一级控矿构造为NEE、NE和NW向构造的交汇部位；吐拉苏地区的一级控矿构造为WNW和NNW及NE方向构造的交汇部位；（2）吐拉苏地区的次级控矿构造为NNE和环形构造的交汇部位；（3）靶区的一级控矿构造为NE、SN和环形构造。线性构造异常分析结果显示，当线性构造的优益度大于40时，有较大的成矿可能性。