南海珊瑚礁铀系年龄及其地质意义   总被引：2，自引：0，他引：2  

夏明  张承蕙  周秀云 《地质科学》1985,(1):12-20

珊瑚礁是铀系方法测定年龄相当理想的对象,在国外已获得十分有价值的成果。主要用于讨论更新世以来海平面变化和构造运动上升速率,研究反映环境的珊瑚生长速度。本文珊瑚礁样品选取于海南岛鹿回头、雷州半岛、西沙和中沙群岛等地。成功地测试了铀系年龄,揭示出与¹⁴C 数据的不一致,初步讨论了构造上升速率和南海海面的变化。  相似文献   

夏季金塔绿洲及邻近沙漠地面风场、气温和湿度场特性的对比分析   总被引：7，自引：4，他引：3  

胡泽勇  吕世华  高洪春  周秀云 《高原气象》2005,24(4):522-526

利用2004年7～8月金塔“绿洲系统能量与水分循环过程观测与数值研究”观测试验期间的资料,对比分析了金塔绿洲及邻近沙漠地面风场和空气温湿特性的水平差异。结果表明：绿洲及邻近沙漠的温湿和风速差异明显,绿洲内部冷湿风弱,而外部干热风稍大;绿洲内的温湿场为非对称结构,冷湿中心偏离绿洲的几何中心,在绿洲东部,当地盛行风向的上风方位置上;而风速场结构对称,弱风中心与绿洲的几何中心一致;在不同的风向时空气比湿有较大的差异,存在明显的来自东北方沙漠戈壁的干平流和来自西南方水库及绿洲的湿平流。  相似文献   

铀浓度和不平衡U²³⁴╱U²³⁸比值在厦门湾海洋水文学研究中的应用     

夏明  张承蕙  周秀云 《海洋科学》1983,7(1):1-5

应用水中U~(234)╱U~(238)此值研究地下水的运动、湖泊水体流动方向、内陆海湖成因和年龄在文献已有报道。本文是应用铀浓度和U~(234)╱U~(238)此在表层水的分布以研究水动力学的特征。讨论海湾区咸淡水混合程度和规模。  相似文献   

α谱法测定低微量铀、钍含量的研究   总被引：1，自引：0，他引：1  

夏明  周秀云 《地球化学》1982,(3):277-284

Alpha-spectrometric technique is described as an independent method of determining micro-content of U^233 and Th^233. This method is based on the comparison of U^234 and Th^233 alpha spectral activity in geological samples with U^232 and Th^233 spectral activity contributed by the spike of known concentration. The experiment procedure consists in dissolving fine powdered sample with acid and adding a given amount of U^232-Th^223 spike. The uranium and thorium are then separated by ion exchange. After purification each fraction is mounted on a separate stainless steel disk for measurement by alpha spectrometer which consist essentially of a surface barrier deterctor and a low noise amplification system connected to a multichannel analyser. After correcting for background, tail and other factors, the desired U^232 and Th^232 concentrations can be calculated. The data obtained by the alpha-spectrometric method using U^232-Th^223 spike are compared with colorimetric determination. Excellent agreement is obtained between the two sets of results. The coefficient of correlation is about 0.98 for U^234 and 0.97 for Th^232. The accuracy of uranium and thorium analyses by this method depends primarily upon the counting statistics of U^233, U^232, Th^233 and Th^223 and, to a lesser extent, upon the calibration of U^233-Th^238 spike. Errors of uranium and thorium concentration by this method are generally 2 to 5 per cent.  相似文献