黑龙江省浅覆盖区地物化特征与找矿标志——以黑河市340高地金矿化区为例

黑龙江省黑河市340高地金矿点大地构造上位于兴安地块东北缘,多宝山Cu-Au-Mo-W-Fe成矿亚带内,其地貌为浅覆盖区,找矿较为困难。本文采用浅钻技术取样,对研究区进行基岩填图,圈定出以硅化为中心、青磐岩化为外围的蚀变矿化带。对基岩样品进行岩石地球化学分析,通过主成分分析,确定有6个主成分特征值大于1,其中第二主成分与金元素关系密切,是研究区有效的找矿标志。高精度磁测结果显示区内构造以NNW向为主,且其线性低值异常或与蚀变引起的退磁有关。对区内的地物化异常进行工程查证,发现金矿点1处,圈定预测靶区1处。     

Chemical and Strontium Isotopic Compositions of the Hanjiang Basin Rivers in China: Anthropogenic Impacts and Chemical Weathering

The Hanjiang River, the largest tributaries of the Changjiang (Yangtze) River, is the water source area of the Middle Route of China’s South-to-North Water Transfer Project. The chemical and strontium isotopic compositions of the river waters are determined with the main purpose of understanding the contribution of chemical weathering processes and anthropogenic inputs on river solutes, as well as the associated CO₂ consumption in the carbonate-dominated basin. The major ion compositions of the Hanjiang River waters are characterized by the dominance of Ca²⁺ and HCO₃ ⁻, followed by Mg²⁺ and SO₄ ²⁻. The increase in TDS and major anions (Cl⁻, NO₃ ⁻, and SO₄ ²⁻) concentrations from upstream to downstream is ascribed to both extensive influences from agriculture and domestic activities over the Hanjiang basin. The chemical and Sr isotopic analyses indicate that three major weathering sources (dolomite, limestone, and silicates) contribute to the total dissolved loads. The contributions of the different end-members to the dissolved load are calculated with the mass balance approach. The calculated results show that the dissolved load is dominated by carbonates weathering, the contribution of which accounts for about 79.4% for the Hanjiang River. The silicate weathering and anthropogenic contributions are approximately 12.3 and 6.87%, respectively. The total TDS fluxes from chemical weathering calculated for the water source area (the upper Hanjiang basin) and the whole Hanjiang basin are approximately 3.8 × 10⁶ and 6.1 × 10⁶ ton/year, respectively. The total chemical weathering (carbonate and silicate) rate for the Hanjiang basin is approximately 38.5 ton/km²/year or 18.6 mm/k year, which is higher than global mean values. The fluxes of CO₂ consumption by carbonate and silicate weathering are estimated to be 56.4 × 10⁹ and 12.9 × 10⁹ mol/year, respectively.     

中国中纬度地带气候暖干化对水资源的影响

中纬度中国,主要指35°N至50°N之间的半湿润至干旱荒漠地带,占中国面积的60%以上,自上世纪末小冰期结束以来,具有鲜明的波动性的增暖和变干趋势,特别是60年代以来更为剧烈。在其影响下,冰川与湖泊萎缩,地表径流减少,地下水位下降,水质恶化,干旱频率和旱灾的严重性都在增加。 在全球变暖的大趋势下,干旱化在近期可能还会继续。但如CO₂及其它微量气体的温室效应导致下世纪升温2℃或更多.重现全新世暖期情景,则中纬度中国会变得湿润起来。而在气候剧变的过渡时期,水旱灾害会进一步增加。     

我国浅成热液金矿的分类探讨

陆相浅成热液金矿是个大概念,是数类金矿的统称。目前对其的分类,不适应理论和应用研究的需要。本文主张以成矿地球动力学环境和矿床本质特征为准则,实施浅成热液金矿的分类。对类型的划分努力体现成因类型和工业类型相结合的原则,并充分反映我国的特点。在矿床类型具体命名时,突出成矿时的浅成深度。文中将我国浅成热液金矿分为浅成脉型、浅成斑岩型和浅成矽卡岩型等三大类八个亚类。陆相浅成热液金矿在我国有广阔的找矿前景,而且在地质产状和成矿作用等方面与国外的殊为不同,值得对其作深入的理论与应用研究。     

北太行山—燕山区中生代金属矿床成矿系统

太行山北段—燕山地区位于中朝板块中部及其北部边缘,以铁、铜、钼、金、银、铅、锌、铀等金属矿产为特色。中生代本区进入陆内造山作用阶段,花岗质岩浆作用及与之有关的成矿作用是克拉通活化的结果。在已研究了与花岗质岩浆作用有关的成矿系列划分、特征和控制因素等基础上,本文重点探讨了成矿系统的划分、时空结构及其控制因素,指出其作为中生代陆内造山作用的结果,明显受到两期不同成矿动力机制的控制,主要由古欧亚构造域成矿系统和西太平洋构造域成矿系统组成。根据构造应力环境,可进一步划分出５个成矿亚系统和Ⅰ～Ⅳ４个成矿系列。成矿系列或矿床具有多期性,不同时代矿床空间分布成带或集中区,三叠纪矿床主要分布于燕辽沉降带北侧,早侏罗世时以辽西为主,中侏罗世时向西扩展到冀东,晚侏罗世时则以太行—燕山西段为主,早白垩世矿床广泛分布于全区,但Ⅲ成矿系列集中等间距分布在几条ＮＷ向带中。矿床这种时空分布规律受控于中生代花岗岩类岩浆活动,而中生代造山作用决定了岩浆岩的时空分布,岩浆起源演化与成矿有关。     

Multivariate analysis of heavy metal pollution in street dusts of Xianyang city, NW China

Urban street dust is one of important indicators of the status of urban environmental pollution. There are many studies in capital cities, but little attention has been paid to this kind of study in medium cities, especially in China. The dust samples were collected in the district of traffic crossroads in Xianyang city, Shaanxi Province. Pb, Cd, Cu, Ni, Zn, Cr and Mn concentrations were determined by using atomic absorption spectrometry. The results indicate that street dusts in Xianyang city have elevated metal concentrations as a whole in comparison with Shaanxi Province soil, except for Mn. The content of heavy metals was comparable to those in capital cities. Correlation coefficient analysis, principal component analysis and cluster analysis were used and three main sources were identified; Mn comes mainly from soil sources; Cu, Zn and Ni are mainly derived from industrial sources combined with traffic sources; Pb, Cr and Cd have traffic sources. Heavy metal enrichment factors were calculated, which can reflect human influence degree of street dusts.     

峰丛洼地坡面流径流过程——以丫吉试验场为例

选取裸露型和土壤植被覆盖型两种峰丛洼地地貌结构.通过降雨量、pH、电导率(Ec)、CO2分压和流量的过程线来分析降雨中详细的产流过程.裸露性坡地因包气带结构简单仅存在局部的超渗产流和表层岩溶带的回归流.水化学性质较稳定;有土壤植被覆盖的坡地的产流过程可以分为3个阶段:补偿阶段(可出现超渗产流)、饱和径流阶段、稳定阶段,补偿阶段仅在降雨强度大于入渗强度时可产生坡面流,饱和径流阶段坡面流流量与降雨强度成正比.稳定阶段坡面流流量趋于稳定,不随雨强的变化而变化,坡面流的水化学性质变化剧烈,pH、电导率(Ec)、CO2分压基本上同步变化,水漫(T)在降雨前期变化规律不明显.后期与pH、Ec等呈相反变化.     

综合物探技术在煤系上覆薄硬岩矿区的应用初探——以山西潞安集团司马矿区为例

山西潞安集团司马矿区东高西低,西部延至长治盆地,矿区水系发育。主采3#煤层埋藏较浅,层位稳定。新生界不整合于下伏基岩之上,厚度变化较大,属典型的薄硬岩煤矿区。为准确提供矿区煤炭开采上限的地质依据,采用了综合勘探技术,其中利用三维地震勘探技术追踪新生界底面反射波及第四系"天窗"位置,利用直流电法与瞬变电磁法提供电性分层,并对其解释结果进行相互印证。勘探实例表明,三维地震勘探、电法勘探与钻探的综合运用不仅可解决薄硬岩煤矿区新生界厚度、含水层富水性及第四系缺失等问题,还可提供新生界含水层与基岩含水层之间的水力联系、制约因素等资料。     

Comparison of linear and nonlinear shallow wave water equations applied to tsunami waves over the China Sea

This paper discusses the applications of linear and nonlinear shallow water wave equations in practical tsunami simulations. We verify which hydrodynamic theory would be most appropriate for different ocean depths. The linear and nonlinear shallow water wave equations in describing tsunami wave propagation are compared for the China Sea. There is a critical zone between 400 and 500 m depth for employing linear and nonlinear models. Furthermore, the bottom frictional term exerts a noticeable influence on the propagation of the nonlinear waves in shallow water. We also apply different models based on these characteristics for forecasting potential seismogenic tsunamis along the Chinese coast. Our results indicate that tsunami waves can be modeled with linear theory with enough accuracy in South China Sea, but the nonlinear terms should not be neglected in the eastern China Sea region.     

Discussion of “Wave setup and setdown generated by obliquely incident waves” by T.-W. Hsu et al., Coastal Engineering, 53, 865–877, 2006

In the recent paper by Tai-Wen Hsu, John R.-C. Hsu, Wen-Kai Weng, Swun-Kwang Wang, and Shan-Hwei Ou (Coastal Engineering, 53, 865–877, 2006), the authors derived theoretical formulations for calculating the wave setup and setdown induced by obliquely incident waves on a beach. The derivation of an expression for setdown contains errors which would lead to an imbalance in longshore momentum flux outside the surfzone. We correct their derivation and give results in terms of the radiation stress concept in a general case including an oblique wave incidence. We also point out that the correct form of wave setdown is important to describe the zero-net force in the momentum balance outside the surfzone.