东乌珠穆沁中铁陨石的金属相冷却速率及其演化历史  

METALLOGRAPHIC COOLING RATE AND EVOLUTIONARY HISTORY OF DONG UJIMQIN MESOSIDERITE

作　　者：王道德[1] 毛艳华[1] 陶克捷[2] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]中国科学院地质研究所,北京100029

出　　处：《地球化学》1998年第2期132-140,共9页Geochimica

基　　金：国家自然科学基金!49772098

摘　　要：采用剖面中间浓度与镍纹石带宽度关系测定了东乌珠穆沁中铁陨石的金相冷却速率，其冷却速率介于0．05℃／Ma与0.02℃／Ma之间，采用铁纹石颗粒或铁纹石带中心镍含量与到最靠近铁纹石颗粒边界或镍纹石带高镍边的关系所获得的冷却速率介于0．1℃／Ma与0．01℃／Ma之间，并与根据镍纹石层纹的测定结果一致。两种方法的测定结果都表明，东乌珠穆沁中铁陨石比任何其他类型陨石更缓慢冷却（＜05℃／Ma）。根据东乌珠穆沁中铁陨石结构和岩石学特征及宇宙射线暴露年龄，该陨石经受了吸积熔融和分异作用-壳的重熔-局部冲击熔融-破裂和重新组合或重新吸积-开挖和喷射等复杂的演化历史。The metallographic cooling rate was measured for the Deng Ujimqin mesosiderite using And profile ac concentration vs. total taenite width. The cooling rates determined from taenite lamellae are 0.05-0.02℃ / Ma. The centful Ni concentrations of kamacite grains or kamacite bands vs. distance to the nearest grain boundary or high Ni edge of taenite lamellae shows a cooling rate of 0.1-0.01℃ / Ma and are consistent with the taenite cooling rate results. Therefore, both methods show that the Deng Ujimqin mesosiderite cooled slower (certainer less than 0.5℃ / Ma) than any other meteoritesdid. Based on texture, Petrographic features and cosmic-ray exposure ages,the Deng Ujimqin mesosiderite has experienced a complex history including accretion,melting and differentiation, crustal remelting, local impact melting, dismption and reassembly or reaccretion and excavation and ejection stages.

关 键 词：东乌珠穆沁 铁陨石 金属相 冷却速率 演化历史 

分 类 号：P185.83[天文地球—天文学]