GEOCHEMISTRY OF SOME GASES IN HYDROTHERMAL FLUIDS FROM THE SOUTHERN JUAN-DE-FUCA-RIDGE
GEOCHEMISTRY OF SOME GASES IN HYDROTHERMAL FLUIDS FROM THE SOUTHERN JUAN-DE-FUCA-RIDGE
复制标题
DOI：
10.1029/jb093ib12p15305
复制
发表时间：
1988-12-10
期刊：
影响因子：
--
通讯作者：
RAPP, JB
中科院分区：
文献类型：
--
作者：
EVANS, WC;WHITE, LD;RAPP, JB
对胡安德富卡山脉南部两个喷口区域的五个热水流体样品进行了溶解气体分析。端员热液中H2(2 70-5 2 7μ/kg)、CH4(82-118μm ol/kg)和CO2(3 92 0-4 460 Mol/kg)的浓度远高于周围海水中的值，与其他山脊水热系统的浓度相似。甲烷(δ13C=−17.8~−20.8)和二氧化碳(δ~(13)C=−3.6~−4.7)的碳同位素比值表明，流体中至少有一部分甲烷和二氧化碳来自玄武岩。玄武岩来源的δ~(13)C值范围为−6.8~−9.7，通过假定热液循环期间ΣCO_2补给守恒计算得出。甲烷和玄武岩来源的二氧化碳之间的表观平衡温度在640℃到750℃之间。在玄武岩中检测到的少量乙烷(C2H6/CH4≅0.9x10−3−2.2x10−3)、丙烷和丁烷也可能在玄武岩中形成。一个几乎纯净的热液样品(95.5%)含有相当大的比例，分别高达补给Ar和N2的63%和74%。这表明该流体没有经历广泛的汽液相分离。
Five samples of hydrothermal fluids from two vent areas on the southern Juan de Fuca Ridge were analyzed for dissolved gases. Concentrations in the end‐member hydrothermal fluid of H2(270–527 μmol/kg), CH4(82–118 μmol/kg), and CO2(3920–4460 μmol/kg) are well above values in ambient seawater and are similar to concentrations reported for other ridge crest hydrothermal systems. The carbon isotopic ratios of the CH4(δ13C = −17.8 to −20.8) and CO2(δ13C = −3.6 to −4.7) suggest that at least some of the CH4and CO2in the fluids is basalt‐derived. The range of δ13C values for the basalt‐derived CO2is −6.8 to −9.7, calculated by assuming conservation of recharge ΣCO2during hydrothermal circulation. Apparent temperatures of equilibration between the CH4and the basalt‐derived CO2range from 640°C to 750°C. Small amounts of ethane (C2H6/CH4≅ 0.9 × 10−3−2.2 × 10−3), propane, and butane detected in the samples may also have formed in the basalt. One sample of almost pure (95.5%) hydrothermal fluid contained a significant fraction, up to 63% and 74%, respectively, of the recharge Ar and N2. This suggests that the fluid has not undergone extensive vapor‐liquid phase separation.