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稀有气体同位素研究,特别是氦同位素的研究,在近十年有了广泛的发展。氦有两种同位素:~3He和~4He。它们在大气中的比值为1.4×10~(-6)。1969年克拉克人等发现海水中~3He/~4He比值高于大气中的10%以后,提出了地球上存在“原始”氦的一种推测。而后相继发现~3He/~4He比值的变化与断层和地震活动有关。在日本松代地震断层带首次发现喷出气体中存在幔源氦这一事实,表明氦同位素的成份变化可能是地震前兆的一种有
Rare gas isotope studies, especially helium isotopes, have undergone extensive development in recent ten years. There are two helium isotopes: ~ 3He and ~ 4He. Their ratio in the atmosphere is 1.4 × 10 -6. After the Clarke found that the ~ 3He / ~ 4He ratio in seawater was 10% higher than that in the atmosphere in 1969, a speculation that there was “primitive” helium on Earth was proposed. After that, the change of the ~ 3He / ~ 4He ratio has been found to be related to the faults and seismic activity. The fact that mantle-derived helium exists in the ejected gas was first detected in the Song-Dai earthquake belt in Japan, indicating that the compositional change of helium isotopes may be a precursor to the earthquake precursors