The origin of gases in Lake Nyos, Cameroon
The origin of gases in Lake Nyos, Cameroon
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喀麦隆尼奥斯湖气体的起源
DOI：
10.1007/978-3-663-05239-5_9
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Y. Sano
中科院分区：
文献类型：
--
作者：
M. Kusakabe;Y. Sano
我们在1988年12月对尼奥斯湖的调查显示，温度、电导率和CO2浓度都有类似的深度剖面，向底部急剧上升。自1986年8月瓦斯爆炸以来，在160米以下，上述测量值已显著增加。这些增加支持了一种观点，即CO是以温暖的、充满CO2的矿化水的形式供应到湖底的。CO2的~ 3 He/~ 4 He比值和~（813）C值分别统一在5.6 ~ 5.7 R（atm）和-3.2 ~-3.7 ‰，强烈表明He和CO2的地幔起源。然而，C /3 He比值为2 × 109 ~ 6 × 1010，高于典型的地幔值2 × 109，可被认为是地幔组分与地壳碳混合的证据，可能来自石灰岩。这种高密度CO2流体可能存在于尼奥斯湖下面的浅层，富CO2流体与地下水接触形成上述CO2饱和的矿化水。
Our survey of Lake Nyos in December 1988 revealed that temperature, conductivity, and CO2concentration, all have similarly shaped depth profiles with a sharp rise towards the bottom. Below 160 m the measurements listed above have significantly increased since the gas burst of August 1986. These increases support a view that CO is being supplied to the lake bottom in the form of warm, CO2-charged, mineralized water. The3He /4He ratios and 813C values of CO2which are uniform at 5.6 to 5.7 R(atm) and -3.2 to -3.7 per mille, respectively, strongly indicate 10 the mantle origin for He and CO2. However, the C /3He ratios of 2 x10to 6 x 1010, which are higher than the typical mantle value of 2 x 109, may be considered as an evidence of mixing of the mantle components with crustal carbon, possibly derived from limestone. It is likely that high density CO2fluid of such origin may be present at a shallow level beneath Lake Nyos, and that contact of the CO2rich fluid with groundwater forms the above-stated, CO2-saturated, mineralized water.