县市级政府决策信息系统的开发应用:专业GIS 软件SK set V4 .0功能介绍———以贵州沿河土家族自治县资源遥感信息系统为例

SK setV4.0是中国地质科学院岩溶地质研究所GIS中心2001年4月开发成功的、具有自主板权的专业GIS平台软件。它集成了现今较为先进的组件、控件重用，面向对象编程等技术，并以美国Inprise公司的BorladnC^ Builder编译软件为开发平台，提供了全中文菜单环境，不仅具有基本信息和多图层查询、相关分析动态监测、多因子分析、图斑编辑、自动演示、系统维护等功能，而且还具有快速响应的工具条、友好的对话框和较强的纠错机制，很适合缺乏专业GIS人才的县市级政府管理部门使用。文中还以贵州省沿河县资源遥感信息系统为例，对SK setV4.0的功能和使用方法进行了具体的介绍。     

Denudation and cooling of the Lake Teletskoye Region in the Altai Mountains (South Siberia) as revealed by apatite fission-track thermochronology

Lake Teletskoye occupies a narrow graben located in the northwestern sector of the Altai fold belt in South Siberia. The lake basin is thought to have formed during the Pleistocene as a distant result of the Cenozoic collision of India and Eurasia that caused a tectonic reactivation of the Palaeozoic Gorny–Altai (GA) and West Sayan (WS) blocks.The present work reports of a pilot fission-track study performed on 13 apatite separates collected from rocks that were sampled along two profiles in close proximity of the lake. The age–length data and AFT thermochronological modelling reveal two important phases of cooling in the Altai Mountains, a first one during the Late Jurassic–Early Cretaceous and a second one that started in the Miocene–Pliocene and that persists until today. The first event is interpreted to result from uplift-induced denudation probably related to the closure of the Mongol–Okhotsk Ocean; the second event can be linked to the young Cenozoic movements that lie at the origin of the formation of the Lake Teletskoye basin.     

Al hematites prepared by homogeneous precipitation of oxinates: material characterization and determination of the Morin transition

A novel method for synthesis of aluminium hematites, based upon the homogeneous precipitation of Fe and Al oxinates in various proportions, is presented. The precursor precipitates are heated in air at 700?°C. X-ray diffraction, thermal analyses, BET, FTIR, optical reflection analysis, TEM and Mössbauer spectroscopy at room temperature and 80?K of the resulting products indicate that single-phase hematites are formed with structural Al substitution of up to 10 at%. Interestingly, the particle size (>100?nm) is not substantially reduced by the Al content. Although it remains difficult to obtain a homogeneously distributed Al substitution in the final hematite, this processing line offers a unique opportunity to separate the effects of grain size and Al substitution on the Morin transition temperature (T _M) of Al hematite. From the comparison between the present hematites and a series of Al-substituted hematites with lepidocrocite as precursor, it could be shown that the effect on T _M, associated with a change of a factor 10 in grain size, is about 1/3 of the effect caused by a change of 10 in the degree of substitution. Finally, it is suggested that proper thermal treatments under different conditions of the same precursors are likely to produce spinel phases.     

厚层覆盖区综合物化探方法找金试验研究——以广西兴安金石金矿为例

在兴安金石金矿外围 4号分散流异常区 ,通过地电化学提取金测量法 ,查明测区存在 5个走向规模小于 5 0 m的金异常区 ,W( Au) 最大值为 72 .4× 10 - 9,高出背景值十几倍 ,并藉综合土壤吸附汞测量 ,高精度磁测和激发极化法等多种物化探方法来确定这些异常区的地质、地球化学和地球物理特征 ,提出金矿成矿的有利部位在金的地电提取高异常区、高汞量异常区、高磁性异常区、低视电阻率异常区和中等视极化率异常区的“三高一低一中”的找矿模式。确定测区的北北东角 (右下角 )一带具备有利的金矿成矿条件     

白云鄂博群中两个重要不整合界面特征及区域对比

白云鄂博群尖山组顶部的钙质风化壳和比鲁特组顶部的铁质风化壳分别代表长城系与蓟县系及蓟县系与青白口系的分界,并具较大区域上的一致性和可对比性。不整合界面的重新厘定,必然导致白云鄂博群的解体或改为白云鄂博超群。     

在"数字国土工程"中我区地学数据库建设的现状及发展趋势

近年来,在国土资源部的高度重视下,我区相继建立了一系列地学数据库。这些地学数据库的建立不仅为地矿行业提供了基础性数据,也加速了"数字国土工程"和国土资源信息化建设的步伐。随着信息技术的高速发展,利用地理信息系统(GIS)将各类地学数据有机地结合起来,形成地学数据应用与管理系统,最终通过网络服务于社会,必将是各类地学数据发展的必然趋势。     

呼伦西白金矿点外围区化异常查证方法及找矿效果

呼伦西白金矿点外围异常查证工作中,采用围山短水系沉积物测量为主,土壤测量为辅的方法,圈定以金为主的综合异常8处,发现金矿脉4条(III～VI号)、锑矿化带1处,取得了较为明显的地质找矿效果。该方法可供同类地区开展异常查证时参考。     

East Asian monsoon instability at the stage 5a/4 transition

The physics involved in the abrupt climate changes of the late Quaternary have eluded paleoclimatologists for many years. More paleoclimatic records characteristic of different elements of the global climate system are needed for better understanding of the cause-feedback relationships in the system. The East Asian monsoon is an important part of the global climate system and the mechanical links between the East Asian monsoon and other climatic elements around the world may hold a key to our knowledge of abrupt climate changes in East Asia and probably over a larger part of the globe. Previous studies have detected millennial-scale winter monsoon oscillations during the last glaciation and probably also during the last interglaciation in loess sequences across China. However, less attention has been paid to the abrupt summer monsoon changes and the stage 5a/ 4 transition, an important period for the evolution of the East Asian monsoon when the global climate shifted towards the last glaciation. Here we report on two loess sections from eastern China which were dated using a thermoluminescence (TL) technique. The pedogenic and other sediment parameters suggest that the summer monsoon experienced a two-step abrupt retreat at the stage 5a/4 transition. The variations in the proxies for the winter monsoon are synchronized with the summer monsoon proxies during this brief interval, implying a direct and immediate link between high latitude and low latitude mechanisms. These changes may be correlated with similar climatic oscillations observed in the North Atlantic, Europe and Antarctica, raising the possibility that the forcing factors that induced these changes are global in extent.     

Fractal analysis of mingled/mixed magmas: an example from the Upper Pollara eruption (Salina Island, southern Tyrrhenian Sea, Italy)

Upper Pollara eruption products (13 ka, Salina Island, Italy) include both homogeneous and heterogeneous pumices resulting from mixing/mingling processes between an HK andesite and a high-SiO₂ rhyolite. Representative samples of heterogeneous pumices are collected and analyzed in order to check the correspondence between glass composition and morphological features of the mingling/mixing structures. Image analysis techniques are applied and eight grey color ranges (classes) are extracted from high-resolution scans of pumice. Class 1 (lighter colors) and class 8 (darker colors) show end-member glass compositions, i.e. HK andesite and high-SiO₂ rhyolite, respectively. These two classes show spot- to cluster-like morphological structures. Intermediate classes show an HK dacitic to rhyolitic composition and a banding- to fold-like morphology. Fractal analysis by box-counting of the boundary pattern of eight grey classified images is performed over a length scale of 0.028–1.8 cm. Fractal dimension D is between 1.01 and 1.84. Coupled fractal analysis and geochemical data reveal that D increases as the degree of magma interaction (homogenization) increases. This feature well fits the results from numerical models on the convective mixing of fluids driven by thermal convection. We conclude that the increase of D observed in the Upper Pollara samples reflects the transition from fractal mixing to homogenization. End-member magmas (HK andesite and high-SiO₂ rhyolite) represent isolated mixing regions, while homogenized magmas represent active mixing regions. In the analyzed pumices, isolated and active mixing regions coexist at scales between 10⁻⁴ and 10⁻² m. Morphological and compositional features of the Upper Pollara pumices result from turbulence.     

内蒙古宝音图岩群变质基性火山岩锆石U-Pb年龄及意义

内蒙古达茂旗宝音图岩群是在达茂旗、查干呼绍地区 1:5万区调和白云鄂博幅 1:2 5万区调过程中从过去的巴特敖包群和白云鄂博群未分岩组解体出来的中级变质岩系。通过对宝音图岩群中阳起钠长片岩、二云片岩 (原岩均为基性火山岩 )进行单颗粒锆石U -Pb法年龄测定 ,获得了两条不一致线上交点年龄 (2 486± 42 )Ma、(2 496± 2 6 )Ma ,代表了宝音图岩群基性火山岩及宝音图岩群的形成时代 ;在不一致线之外不同成因的锆石的2 0 7Pb/ 2 0 6Pb表面年龄 (2 2 2 7± 15 )Ma ,寓示着 2 2 0 0Ma左右发生了一次区域性变质热事件 ;下交点年龄 (319±486 )Ma和 (40 6± 46 )Ma ,代表了 2 5 0～ 480Ma时期该区大面积岩浆侵位及宝音图岩群后期变形变质改造的时期 ,两个年龄样的获得为研究古元古代古陆的裂解及白云鄂博海槽的形成提供了直接依据。