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991.
The Maozu Pb–Zn deposit, located on the western margin of the Yangtze Block, southwest China, is a typical carbonate-hosted deposit in the Sichuan–Yunnan–Guizhou Pb–Zn metallogenic province with Pb + Zn reserves of about 2.0 million tonnes grading 4.15 wt.% Pb and 7.25 wt.% Zn. Its ore bodies are hosted in Sinian (635–541 Ma) Dengying Formation dolostone and show stratiform, vein and irregular textures. Ores are composed of sphalerite, galena, pyrite, calcite, dolomite, quartz and fluorite with massive, banded, disseminated and veined structures. The C–O–Sm–Nd isotopic compositions of hydrothermal calcites and S–Pb isotopic compositions of sulfides were analyzed to constrain the origin of the Maozu deposit. δ13CPDB and δ18OSMOW values of hydrothermal calcites range from −3.7‰ to −2.0‰ and +13.8‰ to +17.5‰, respectively, and plot near the marine carbonate rocks field in a plot of δ13CPDB vs. δ18OSMOW, with a negative correlation. It suggests that CO2 in the hydrothermal fluids was mainly originated from marine carbonate rocks, with limited influence from sedimentary organic matter. δ34SCDT values of sulfides range from +9.9‰ to +19.2‰, similar to that of Cambrian to Triassic seawater sulfate (+15‰ to +35‰) and evaporate (+15‰ to +30‰) in the Cambrian to Triassic sedimentary strata. It suggests that reduced sulfur was derived from evaporate in sedimentary strata by thermo chemical sulfate reduction. Sulfides have low radiogenic Pb isotope compositions (206Pb/204Pb = 18.129–18.375, 207Pb/204Pb = 15.640–15.686 and 208Pb/204Pb = 38.220–38.577) that plot in the field between upper crust and the orogenic belt evolution curve in the plot of 207Pb/204Pb vs. 206Pb/204Pb, and similar to that of age corrected Proterozoic basement rocks (Dongchuan and Kunyang Groups). This indicates that ore-forming metals were mainly derived from basement rocks. Hydrothermal calcite yields a Sm–Nd isotopic age of 196 ± 13 Ma, possibly reflecting the timing of Pb–Zn mineralization in the SYG province, younger than the Permian Emeishan mantle plume (∼260 Ma). All data combined suggests that hydrothermal fluids circulated through basement rocks where they picked up metals and migrated to surface, mixed with reduced sulfur-bearing fluids and precipitated metals. Ore genesis of the Maozu deposit is different from known magmatic–hydrothermal, Sedimentary Exhalative or Mississippi Valley-types, which maybe represent a unique ore deposit type, named as the SYG-type. 相似文献
992.
Mohammad Wasim Mohammad Arif Sajid Iqbal Muhammad Daud 《Geostandards and Geoanalytical Research》2013,37(1):87-93
The International Atomic Energy Agency (IAEA) organised a proficiency test (PT), IAEA‐CU‐2010‐02, for the determination of elements in sewage sludge. The PT sample was analysed by semi‐absolute standardless k0‐instrumental neutron activation analysis (k0‐INAA). Results for seven elements (As, Co, Cr, Fe, Hg, Se, Zn) were submitted to the IAEA by our laboratory. All of our results were scored ‘acceptable’ by the ‘result evaluation criteria’ adopted by the IAEA. The same analytical methodology produced quantitative results for twenty‐six additional elements. In total, thirty‐six elements were determined with uncertainty varying from 4 to 11%. This paper presents the provisional mass fractions of twenty‐six additional elements (Ag, Al, Br, Ca, Ce, Cl, Dy, Eu, Ga, Hf, I, K, La, Mg, Mn, Na, Rb, Sb, Sc, Sm, Ta, Tb, Th, V, U, W) not reported by the IAEA. The analytical methodology was discussed with important sources of spectral, nuclear and fission‐product interferences. It was shown that the important components of uncertainties were the k0 factor, Q0 factor, detector efficiency, mass and counting statistics. The methodology was validated by analysing the IAEA‐S7 reference material. 相似文献
993.
以现有地质及地震资料为基础,对阿姆河右岸区块东南部靠近吉萨尔山前地区的中下侏罗统主要构造特征进行探讨,一方面有利于促进该区中下侏罗统油气勘探,同时也有利于深化对造山带向盆地过渡的山前地区构造变形规律的认识。研究表明:该区中下侏罗统整体表现为由三列近似呈雁行状排列的NE向背斜带组成的褶皱-冲断构造。从控制背斜构造发育的断裂活动特征看,东部山前断层表现为由南东向北西方向逆冲,活动强度大,向西逆断层运动的强度逐渐减弱,且由南向北西部断层的逆冲运动方向发生反向变化,在研究区的北部发育典型的构造三角带。西部背斜带可视为断裂运动方式由南向北变化导致的调节构造。沿构造带走向,三列背斜构造高点由南向北逐渐升高。通过对中下侏罗统构造变形与上覆地层构造特征的比较,结合该区侏罗系沉积特征,认为中下侏罗统构造变形是与上覆地层构造变形共同形成于新近纪喜山期统一的区域构造运动背景下。其主要构造变形机制是晚古近-新近纪以来,在印度板块、阿拉伯板块和欧亚板块碰撞远程效应影响下,受吉萨尔山脉的隆升挤压和研究区北部NW向的大型断裂如布哈拉断裂、曼格什拉克断裂的右旋压扭共同作用而成。 相似文献
994.
995.
TAN Yuanlong QIAO Yansong ZHAO Zhizhong WANG Yan QI Lin FU Jianli LIU Zongxiu YAO Haitao WANG Shubing JIANG Fuchu 《《地质学报》英文版》2013,87(6):1712-1723
In this study Chengdu Red Earth (CRE) from the Chengdu Plain (CP),Sichuan province,was analyzed for its elemental (major and trace elements) and isotopic (Sm-Nd) geochemistry and compared with Pleistocene loess and paleosol samples from the Chinese Loess Plateau (CLP) in Northern China.The geochemical composition of CRE is similar to north China loess,and also resembles the average UCC.This indicates that CRE,as loess deposits in Northern China,was derived from well-mixed sedimentary protoliths that have undergone numerous upper crustal recycling processes.However,obvious differences in the geochemical characteristics of CRE and the north China loess are also revealed in our results.For chemically stable elements,CRE has higher Ti,Zr,Hf and lower ΣREE,Ba contents in comparison with loess samples from the CLP.Further analysis shows that CRE has higher TiO2/Al2O3,SiO2/Al2O3,Ba/Rb and lower Ce/Yb,Eu/Yb,LaN/YbN and ΣLREE/ ΣHREE ratios.In Sm-Nd isotopic geochemistry,Sm and Nd content and the εNd(0) value in CRE are significantly higher than those in north China loess.The higher TiO2 content in CRE coincided with a high background concentration of Ti in the Sichuan Basin and the surrounding regions.The lower ΣREE and higher Sm,Nd,εNd(0) values are related to the wide distribution of basalt in the southwest Sichuan Basin.The elemental and isotopic geochemistry of CRE indicates that eolian materials in the CP predominantly come from the Sichuan Basin and the surrounding regions,which differs from loess deposits in the CLP. 相似文献
996.
矿山开发给矿区环境带来了负面影响,对矿山环境质量进行评价是实现矿业可持续发展的必要手段。笔者建立了矿山岩土工程环境质量多目标评价指标体系,运用层次分析法确定出各个评价指标的权重; 规定了分级规则,并对各个评价指标进行了分级; 建立了矿山岩土工程体系环境质量多目标综合评价模型,并将该模型应用于矿山实际,得出该矿山环境质量较差,需及时采取措施进行治理。 相似文献
997.
重庆市巫山县环湖路地质条件十分复杂,沿线经过十几个地质灾害单元体。环湖路经过淀粉厂滑坡区时,以半挖半填的方式经过。环湖路建设对原滑坡体的稳定性影响进行重新评价计算,认为原设计方案不能满足要求,对原方案进行修改设计,完成淀粉厂滑坡的施工治理的环湖路的建设,实现了淀粉厂滑坡和环湖路工程建设的安全稳定。 相似文献
998.
北京市永定河冲洪积扇中上部,具备建设地下水库的基本条件。本文在确定永定河地下水库水资源人工补给方式的基础上,分析了各方式的入渗能力,提出了地下水库的人工补给方案,利用地下水数值模拟的预测结果和有效储水率计算公式,首次研究了地下水库的储水能力,分析了永定河地下水库的水资源补给效果。结果表明,永定河地下水库水资源人工补给能力最大可达18.93m^3/s,回灌地表水2.42×108m^3的情况下地下水位最大回升32m,地下水储存量增加2.09×108m^3,回灌后1年和5年的有效蓄水率分别为78.6%和46.8%,北京永定河地下水库具有较好水资源回灌能力、储存能力,地下水人工调蓄能够起到明显的效果。 相似文献
999.
1000.