地幔中铀的存在状态及其地球化学含义  

Occurrence states of uranium in the mantle and their geochemical implication

作　　者：杜乐天[1] 王文广[1] 

机构地区：[1]核工业北京地质研究院,北京100029

出　　处：《地学前缘》2005年第1期69-78,共10页Earth Science Frontiers

摘　　要：用235U诱发裂变径迹法对地幔岩捕虏体中铀的分布、含量及存在状态进行了详细的镜下径迹统计,以揭示铀元素在地幔岩中的种种存在状态和分布规律。在此基础上进一步把铀作为不相容元素群的示踪剂(tracer),指示地幔流体在深部地幔岩中的活动轨迹。结果表明,地幔流体能够渗透到各造岩矿物颗粒间隙、浆胞、蚀变边和晶体内部超微裂隙之中(此裂隙宽度很小,约为0.00 n^0.0 n mm)。地幔流体残渣呈极易浸出的非矿物形式的烃碱性物质吸附在超微裂隙之中(浸泡液pH>10)。通过浸泡结果能够大体窥知当初地幔流体的可能地球化学成分。In this paper, the distribution, abundance and occurrence states of U in mantle xenoliths are studied by ^(235)U fission track method, and the movement of mantle fluids is revealed by means of U-tracer, which is a representative of incompatible elements in the mantle. The results show that the mantle fluids can penetrate into and concentrate in the ultra-microfissures of crystals, in the space between mineral grains, and in magmatic cell glasses. The leached (by water at room temperature) materials from xenoliths, which are considered as relics of mantle fluids are very soluble (pH >10) hydrocarbon-alkali substances. Using the leached results, we can distinguish the components of mantle fluids.

关 键 词：地幔铀 裂变径迹 地幔流体 不相容元素 

分 类 号：P619.14[天文地球—矿床学]