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山西宁武煤田的大同组 总被引:3,自引:0,他引:3
宁武煤田的大同组主要由黄绿色、灰绿色砂岩、砂质泥岩、粉砂岩及泥岩组成,夹有薄层灰岩及煤层,为一套湖泊到湖泊三角洲相含煤沉积。底界置于铜川组紫红色泥岩之顶,顶界为云岗组灰绿色砂岩之底,厚283~461m。本组含丰富的植物化石,可归于Coniopteris-Phoenicopsis植物群,时代为中侏罗世。 相似文献
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Marine carbonate skeletons like deep-sea corals are frequently coated with iron and manganese oxides/hydroxides which adsorb additional thorium and uranium out of the sea water. A new cleaning procedure has been developed to reduce this contamination. In this further cleaning step a solution of Na2EDTA (Na2H2TB) and ascorbic acid is used which composition is optimised especially for samples of 20 mg of weight. It was first tested on aliquots of a reef-building coral which had been artificially contaminated with powdered ferromanganese nodule. Applied on heavily contaminated deep-sea corals (scleractinia), it reduced excess 230Th by another order of magnitude in addition to usual cleaning procedures. The measurement of at least three fractions of different contamination, together with an additional standard correction for contaminated carbonates results in Th/U-ages corrected for the authigenic component. A good agreement between Th/U- and 14C-ages can be achieved even for extremely coated corals. 相似文献
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沉积相分析表明,平庄盆地五家矿区煤系由湖泊体系、扇三角洲体系、冲积扇体系、河流体系和湖泊三角洲体系构成。其沉积环境演化经历了湖泊扩张、迅速萎缩、缓慢淤浅、消亡(冲积扇—辫状河为主要地理景观)4个阶段。湖泊缓慢淤浅阶段的湖滨和扇三角洲平原是聚煤的主要环境。 相似文献
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研究了高技术局部战争条件下,军事地理环境研究内容及特点变化,探讨了高技术武器装备对军事地理保障是高技术局部战争制胜的重要基础。 相似文献
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徐耀通 《大地构造与成矿学》1992,16(4):325-336
构造地球化学障就是在构造地球化学场中元素浓度梯度极大值所在的地质构造地段.其本质是构造地球化学环境发生突变.而使元素活动性急剧降低从而发生元素构造地球化学分异和沉淀作用的地质构造地段.本文运用构造地球化学障成矿理论对丰山矿田的断裂构造地球化学障,褶皱构造地球化学障、接触带构造地球化学障及其成矿作用作了系统研究. 相似文献
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在对现有地质灾害调查研究的基础上,提出了防治地质灾害的基本方针和主要措施,对建设生态矿业城市有一定指导意义。 相似文献