METHANE HYDROGEN GAS SEEPS, ZAMBALES OPHIOLITE, PHILIPPINES - DEEP OR SHALLOW ORIGIN
METHANE HYDROGEN GAS SEEPS, ZAMBALES OPHIOLITE, PHILIPPINES - DEEP OR SHALLOW ORIGIN
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DOI：
10.1016/0009-2541(88)90116-7
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发表时间：
1988-12-15
期刊：
影响因子：
3.9
通讯作者：
STEVENS, CM
中科院分区：
文献类型：
--
作者：
ABRAJANO, TA;STURCHIO, NC;STEVENS, CM
菲律宾赞巴莱蛇绿岩蛇纹化超镁铁质岩中低流速和环境温度下同位素异常富甲烷气体逸出。气体的主要成分是CH 4（55mol%）和H2（42mol%），CH 4 CO2比> 1800，CH 4 He比为9.2·104。CH 4的δ 13 C值为− 7.0±0.4‰（PDB），比其他天然气和温泉中CH 4的最高公布值高出1.8 ‰，但与通常归因于地幔碳的值相似。3 He 4 He的比值为5.70· 10− 6，是大气比值的4.1倍，表明地幔中有大量的He成分。CH 4和H 2的δ D值分别为− 136和− 590‰，与110-125° C的平衡温度一致。碳和氦同位素数据可能与赞巴莱天然气直接来自还原地幔的推导是一致的。然而，相平衡和氢同位素数据表明，天然气也可能是在蛇绿岩低温蛇纹石化过程中通过水和碳的还原而产生的。
Isotopically anomalous CH 4-rich gas escapes at low flow rate and ambient temperature from seeps in serpentinized ultramafic rock in the Zambales Ophiolite, Philippines. The major components of the gas are CH 4 (55 mole%) and H 2 (42 mole%); the CH 4 CO 2 ratio is> 1800 and the CH 4 He ratio is 9.2· 10 4. The δ 13 C-value of the CH 4 is− 7.0±0.4‰(PDB),∼ 8‰ higher than the highest published values for CH 4 in other natural gases and hot springs, but similar to values commonly attributed to mantle carbon. The 3 He 4 He ratio is 5.70· 10− 6, 4.1 times the atmospheric ratio, indicative of a substantial mantle He component. The δD-values of CH 4 and H 2 are− 136 and− 590‰, respectively, consistent with equilibration temperatures of 110–125° C. Carbon and He isotopic data could be consistent with derivation of the Zambales gas directly from a reduced mantle. However, phase equilibria and H isotope data indicate that the gas also could have been produced by reduction of water and carbon during low-temperature serpentinization of the ophiolite.