滇西马厂箐铜钼多金属矿床成矿流体来源及演化过程——来自石榴子石原位微量元素及H- O同位素组成的限定

滇西马厂箐铜钼多金属矿床位于三江特提斯成矿域,是一个与喜马拉雅期富碱斑岩侵入有关的多金属矿床。前人研究表明,马厂箐铜钼多金属矿床形成于斑岩-矽卡岩成矿系统,但由于缺乏系统矿物学研究,目前对矽卡岩矿化过程和成矿效应仍不清楚,限制了对该矿床成矿过程的全面认识。因此,本文以马厂箐矿床矽卡岩型矿化中的石榴子石为研究对象,利用H-O同位素、电子探针(EPMA)以及LA-ICP-MS原位微区技术开展了同位素及成分分析,限定成矿流体来源以及反演成矿流体演化过程。石榴子石可分为早期自形石榴子石(Grt I)和晚期他形石榴子石(Grt II)。Grt I与辉石共生,并伴有黄铁矿、黄铜矿等金属矿物组合,属于钙铝-钙铁榴石固溶体(And_{49.37～99.58}Gro_0～49.79);Grt II更富Fe,属钙铁榴石系列(And_{67.50～99.85}Gro_0～31.84)。两期石榴子石均富含Th、U、Nd,亏损Ba、Sr、Hf、Nb,富轻稀土。基于石榴子石矿物化学特征认为,Grt I可能是在弱酸性、氧化、低水岩比(W/R)条...     

云南羊拉铜矿矽卡岩形成时代与矿床成因：来自石榴子石和磁铁矿组分的约束

羊拉铜矿是金沙江缝合带中部已发现的规模最大的印支期铜矿床,矿体以层状—似层状产出于花岗闪长岩外围、变质砂岩与碳酸盐岩地层的层间破碎带中。该矿床在成因类型上存在喷流-沉积成因、复合成因、矽卡岩成因等多种观点。本文以矽卡岩矿石中石榴子石、磁铁矿为研究对象,利用LA-ICP-MS原位微区分析技术开展了石榴子石U-Pb年代学和石榴子石、磁铁矿成分测试分析,以进一步限定该矿床成矿时代和成因类型。分析结果显示,石榴子石中U、Th、Pb的含量分别为1.18×10^-6～6.69×10^-6、0.04×10^-6～1.43×10^-6、0.11×10^-6～1.16×10^-6,获得Tera-Wasserburg下交点年龄为231.0±5.3 Ma(2σ,n=32,MSWD=2.1),与矿区花岗闪长岩形成时代高度一致。结合磁铁矿微量元素组成与全球矽卡岩型矿床可类比等特征,明确羊拉铜矿床属于典型矽卡岩型铜矿床。石榴子石以钙铁榴石组分为主,具轻稀土富集、重稀土亏损的配分模式,这可能受晶体...     

基于宁东干旱特点的水土保持生态环境变化研究

干旱是一种涉及自然、经济、社会的气候现象,长期困扰着工农业生产.分析宁东能源化工基地气候干旱特点,预防以土壤旱化为主要特征的地力衰退和土壤退化等现象在宁东基地再现.研究以MODIS NDVI遥感数据为基础数据,结合研究区同期降雨量和温度数据,采用降水量距平百分率法作为宁东基地干旱评估的方法,根据干旱评估国家标准分析宁东基地的干旱时空分布特点,分析2000—2015年研究区植被覆盖度对气候变化的响应.研究结果表明:1)宁东基地春旱的发生频率明显高于夏季,发生春夏连旱的频率小于单季旱;2)宁东基地干旱发生随机性大,没有明显的规律性,干旱预报困难;3)2000—2015年16年间每年都有不同程度的干旱发生,宁东基地干旱发生具频繁性的特点;4)宁东基地降水量与NDVI平均值有较强的相关性,相关系数达到0.5907,对宁东基地生态恢复有较好的指示作用.     

基于FME的不动产单元测绘数据技术审查

保障不动产单元测绘的规范性,可推进不动产登记协同办公、加强政府监督、提升政府宏观调控能力,提升政府便民利民的服务水平.本文阐述了不动产单元测绘数据技术审查的技术审查流程,并基于FME(feature manipulate engine)实现了不动产单元测绘数据的质量检查,同时针对存在的疑难问题进行了分析,并给出了指导建议.实践证明,本文取得了预期成果,具有很强的实用价值.     

Turnover Frequency in Solar Microwave Bursts with an Extremely Flat Optically Thin Spectrum

Four microwave bursts have been selected from the Nobeyama Radio Polarimeter (NoRP) observations with an extremely flat spectrum in the optically thin part and a very hard spectral index between 0 and ?1 in the maximum phase of all bursts. It is found that the time evolution of the turnover frequency is inversely proportional to the time profiles of the radio flux in all bursts. Based on the nonthermal gyrosynchrotron theory of Ramaty (Astrophys. J. 158, 753, 1969), the local magnetic field strength and the electron spectral index are calculated uniquely from the observed radio spectral index and the turnover frequency. We found that the electron energy spectrum is very hard (spectral index 1?–?2), and the time variation of the magnetic field strength is also inversely proportional to the radio flux as a function of time in all bursts. Hence, the time evolution of the turnover frequency can be explained directly by its dependence on the local magnetic field strength. The high turnover frequency (several tens of GHz) is mainly caused by a strong magnetic field of up to several hundred gauss, and probably by the Razin effect under a high plasma density over \(10^{10}~\mbox{cm}^{-3}\) in the maximum phase of these bursts. Therefore, the extremely flat microwave spectrum can be well understood by the observed high turnover frequency and the calculated hard electron spectral index.     

Latest Devonian to earliest Carboniferous conodont and carbon isotope stratigraphy of a shallow‐water sequence in South China

To improve regional and intercontinental correlation of the uppermost Devonian–lowermost Carboniferous, we examined the conodont faunas and carbon isotopic records of the Tangbagou Formation in the Qilinzhai section, southern Guizhou, South China. The Tangbagou Formation is a succession of mixed carbonate–siliciclastic rocks that accumulated on a shallow‐water platform under normal marine conditions. Seven conodont zones for shallow‐water biofacies in South China, the Cl. gilwernensis–Cl. unicornis Zone, the Po. spicatus Zone, the Si. homosimplex Zone, the Si. sinensis Zone, the Si. eurylobata Zone, the Ps. multistriatus Zone and the Po. co. porcatus Zone in ascending order, are recognized in the Tangbagou Formation. Although apparently limited in its value for global correlation, this conodont zonation is more applicable to shallow‐water biofacies in South China. Carbonate samples have yielded carbon isotopic signatures consistent with those recorded in Euroamerica sections, in particular showing four distinct characteristics: (1) the peak values of Hangenberg Carbon Isotope Excursion (HICE) during the latest Devonian, (2) a minor positive shift (P1) in the Si. homosimplex Zone during the early Tournaisian, (3) a second minor positive shift (P2) in the Si. sinensis Zone and (4) the middle Tournaisian Carbon Isotope Excursion (TICE) in the middle part of the Tangbagou Formation. The similarity in peak values (~5.5‰) and magnitude of TICE for the Qilinzhai and Belgian sections indicates that the Euro‐asia δ¹³C_carb trends may reflect the changes in global mean ocean δ¹³C_DIC, rather than having been overprinted by local carbon cycling. Integration of conodont biostratigraphy and δ¹³C stratigraphy provides a powerful tool for stratigraphic correlation. Copyright © 2015 John Wiley & Sons, Ltd.     

太平洋潜热通量及其与黄淮夏季降水的关系

研究了1979—2010年太平洋潜热通量的变化特征及其与中国黄淮夏季降水的关系。结果表明,潜热通量的气候场和方差场均存在着明显的季节变化,且各季节气候场的极值中心也是变化幅度较大的区域。黄淮地区降水与前期春季的潜热场相关性最好。定义了黄淮夏季降水指数来研究影响降水的潜热场关键区,发现春季潜热关键区为10°~20°N之间的中东太平洋和热带东太平洋沿岸海区。春季当上述两个海区净潜热通量增多时,后期夏季500hPa和850hPa位势高度异常场中,在太平洋西海岸-阿拉斯加南部一线上均表现为"正—负—正"的分布型,黄淮降水偏多。