玻利维亚铜金锡铁主要矿床类型及资源潜力

玻利维亚的铜矿规模以中小型为主,主要成矿类型为红层型(砂岩层)、沉积相关脉状型、VMS型和IOCG型等。金矿规模以中小型为主,主要成矿类型有火山成因浅成热液型、与深成岩相关的脉状矿床、造山型矿床和砂金矿。锡矿发育众多大型、超大型矿床,成矿类型以玻利维亚型多金属脉状矿床和与长英质深成岩相关的脉状矿床为主,少量砂锡矿。铁矿以El Mutún超大型BIF型铁锰矿著称。西科迪勒拉和玻利维亚高原有重要的浅成低温热液贵金属资源潜力;东科迪勒拉北部主要为钨、锡、金、锑资源,中部为锡、银、金、锑资源,南部有金、锑、银、铅、锌潜力;次安第斯带南部有银-锌资源潜力;查科-贝尼平原带有广泛的砂金矿资源;前寒武纪克拉通内金、铂、镍、钽、铜和铁锰资源潜力丰富。     

Quantifying the carbon source of pedogenic calcite veins in weathered limestone: implications for the terrestrial carbon cycle

The continent is the second largest carbon sink on Earth’s surface. With the diversification of vascular land plants in the late Paleozoic, terrestrial organic carbon burial is represented by massive coal formation, while the development of soil profiles would account for both organic and inorganic carbon burial. As compared with soil organic carbon, inorganic carbon burial, collectively known as the soil carbonate, would have a greater impact on the long-term carbon cycle. Soil carbonate would have multiple carbon sources, including dissolution of host calcareous rocks, dissolved inorganic carbon from freshwater, and oxidation of organic matter, but the host calcareous rock dissolution would not cause atmospheric CO₂ drawdown. Thus, to evaluate the potential effect of soil carbonate formation on the atmospheric pCO₂ level, different carbon sources of soil carbonate should be quantitatively differentiated. In this study, we analyzed the carbon and magnesium isotopes of pedogenic calcite veins developed in a heavily weathered outcrop, consisting of limestone of the early Paleogene Guanzhuang Group in North China. Based on the C and Mg isotope data, we developed a numerical model to quantify the carbon source of calcite veins. The modeling results indicate that 4–37 wt% of carbon in these calcite veins was derived from atmospheric CO₂. The low contribution from atmospheric CO₂ might be attributed to the host limestone that might have diluted the atmospheric CO₂ sink. Nevertheless, taking this value into consideration, it is estimated that soil carbonate formation would lower 1 ppm atmospheric CO₂ within 2000 years, i.e., soil carbonate alone would sequester all atmospheric CO₂ within 1 million years. Finally, our study suggests the C–Mg isotope system might be a better tool in quantifying the carbon source of soil carbonate.

     

对吉林省“晚印支亚构造层”归属的一点认识

本文对吉林省“晚印支亚构造层”的归属进行了重新认识,建立了“晚印支—燕山亚构造层”,这一认识可以通过上三叠统沉积建造、地层接触关系,构造变形特征及构造格局转化加以证明,并与按大地构造性质所划分的构造层具有一致性。     

QUANTITATIVE ANALYSIS OF UN-MEASURED BED LOAD AT DIVERSION INTAKES OF THE YELLOW RIVER IN SHANDONG PROVINCE

1 INTRODUCTION At present, most of the instruments used for sampling sediment loads at the canal intakes along the Yellow River in Shandong Province are horizontal samplers. These kinds of samplers cannot sample the suspended load 0.3 m from the riverbed. More recently use of bottle samplers has allowed sampling of the sediment load up to 0.1 m from the riverbed. However, bottle samplers are not able to measure suspended loads with high sediment concentrations and coarse sediment particl…     

使用Ghost自动备份和恢复操作系统

当计算机出现非法操作、死机、运行缓慢、病毒或者操作的失误,导致硬盘上的数据丢失和系统崩溃如此类问题时,采用Ghost软件自动备份和恢复操作系统。     

利用GPS测定大型桥梁动态特性的试验及结果

为研究GPS测定桥梁结构自振特性的可行性 ,结合武汉长江二桥开展了一次GPS动态监测试验工作 ,介绍了试验实施方案及其监测结果。通过应用频谱分析法 ,有效地获取了斜拉桥跨中的振动特征 ,其结果与竣工时采用加速度计实测的值十分吻合。研究表明 ,应用高采样率的GPS接收机和合理的数据处理方法 ,完全可以高精度地实现桥梁结构自振特性的确定     

第四系科学钻探及地层对比方法探讨

随着社会经济发展的需要,地方经济可持续发展中部分环境、资源问题的基础——第四纪地质变得日益重要,第四系钻探作为第四系覆盖区填图的重要工作手段,钻探质量及编录资料的质量直接影响着第四系区域填图成果的表达。该文结合1∶5万辛安庄等五幅区调项目实践经验,对第四系科学钻探的工作流程进行了总结,并对第四纪钻孔多重地层划分与区域对比方法进行了初步的探讨。     

基于3DMine的断面法与距离幂次反比法对比

以坦桑尼亚纳钦圭阿大型晶质石墨矿南部矿体为研究对象,基于3DMine软件平台,通过垂直断面法、距离幂次反比法进行资源量估算,对比研究2种资源量估算方法在矿体的体积、品位、资源量方面的区别。结果表明：2种估算方法体积相对误差为6.30%,品位相对误差为1.45%,资源量结果相对误差为7.83%,资源量验算结果在误差范围之内;3DMine中的断面法计算过程自动、准确、高效,利用三维模型体积替代传统公式计算体积,计算结果更加精准;采用距离幂次反比法时,运用三维模型计算矿体体积,用全局验证和交叉验证对搜索椭球体参数的合理性进行验证,最终选择最优搜索椭球体参数,是进行资源量准确估算的关键。综上所述,用距离幂次反比法估算的资源量结果更加准确,计算过程高效、便捷,并可为后期矿山数字化建设提供基础,是今后矿山发展的趋势。     

基于斜坡单元的山区城镇滑坡灾害易发性评价：以康定为例

山区地质灾害易发性评价对城镇地质灾害风险管理具有重要意义。本文以康定市为例,以斜坡单元为最小评价单元,选取高程、坡度、坡向、曲率、工程地质岩组、距道路距离、距断裂距离、距水系距离和斜坡结构等9个滑坡影响因子,根据各因子滑坡面积比曲线与证据权值曲线的突变点,划分滑坡影响因子二级状态,并对各影响因子进行相关性分析,剔除相关性较高的距道路距离因子,在此基础上,采用证据权模型进行滑坡易发性评价。对已有治理工程的斜坡单元,本文尝试利用折减系数法对其易发性进行进一步评价。结合现场调查,将研究区滑坡易发性程度划分为：极高易发、高易发、中等易发、低易发。评价结果表明,自然工况下极高易发区主要位于康定市炉城镇以及研究区北侧二道桥村一带,高易发区主要位于雅拉河、折多河与瓦斯沟河谷两侧,对治理工程所在的斜坡单元进行折减后,极高易发区面积由11.21%降至8.42%,滑坡比率由4.03降低至2.3,研究结果符合实际情况,模型精度达77.8%。评价结果较好地反映了康定市区的滑坡易发性分布情况,可为城镇精细化评价提供一定的参考依据。     

典型内陆湖泊沉积物氮、磷和重金属分布特征及生态风险评价——以武汉市武湖为例

城市内陆型湖泊湿地对城市生态系统具有重要的作用。以武汉市武湖为例,采用数理统计、营养盐指数、地累积指数和潜在生态风险指数等方法,对武湖表层沉积物中的氮、磷、有机质和重金属的平面分布特征、影响因素、富集污染程度、生态风险进行评价。结果表明: 武湖西北部表层沉积物中总氮、总磷和有机质的含量明显高于东南部,武湖周边地表径流和农田是营养元素的主要来源,旱地较水田有利于沉积物中总磷的富集; 武湖沉积物中有机质为内源水生植物和外源陆生植物的混合来源,与总氮具显著正相关关系; 沉积物中重金属含量总体较低,局部呈现高镉,平面上总体北部高于南部; 沉积物中重金属富集程度和潜在风险较低,局部地区镉和铅为轻微富集,镉和汞具中等潜在风险; 沉积物的潜在生态风险为低至中等,潜在生态风险与沉积物中镉的分布高度一致。