【摘要】 <正> 金是亲铁元素,金的浓度与其他一些亲铁元素(如铱、锇、镍、钴和铁等)的相关性具有重要的地球化学与宇宙化学意义。Au与Ir属同一类元素,但地壳岩石中的Ir/Au比值较低,这表明金和铱的地球化学行为并不完全相同,而上地幔岩石具有未分馏的球粒陨石之Ir/Au比值。一般认为宇宙尘中的Ir/Au比值要比碳质球粒陨石高一些,这是因为更多还原

【Abstract】 Gold contents and its abundance variations in some spherules taken from pelagic sediments, ancient strata and simulated meteorite samples were studied with instru-mental NAA technique of high sensitivity and specificity. The experimental results re-vealed that the concentration of gold in silicate spherules ranges from a few to 30 ppb and the depletion factors relative to C1 meteorites are within the range of 10 to 100, while the magnetic spherules exhibit considerably large scatter in gold concentration, re-flecting the features of their precursors. Ir/Au ratios in various types of cosmic dust fall into the range of extraterrestrial materials (about 3.3). Therefore, Ir/Au can be used as a "fingerprint" of identifying the origin of cosmic dust.更多还原