汤加丽, 曹运诚, 陈多福. 大洋蛇纹岩化无机成因甲烷水合物稳定带底界模拟[J]. 海洋地质与第四纪地质, 2020, 40(4): 107-115. DOI: 10.16562/j.cnki.0256-1492.2019081701
引用本文: 汤加丽, 曹运诚, 陈多福. 大洋蛇纹岩化无机成因甲烷水合物稳定带底界模拟[J]. 海洋地质与第四纪地质, 2020, 40(4): 107-115. DOI: 10.16562/j.cnki.0256-1492.2019081701
TANG Jiali, CAO Yuncheng, CHEN Duofu. Simulation of bottom boundaries of abiotic methane hydrate stability zone in some marine serpentinization areas[J]. Marine Geology & Quaternary Geology, 2020, 40(4): 107-115. DOI: 10.16562/j.cnki.0256-1492.2019081701
Citation: TANG Jiali, CAO Yuncheng, CHEN Duofu. Simulation of bottom boundaries of abiotic methane hydrate stability zone in some marine serpentinization areas[J]. Marine Geology & Quaternary Geology, 2020, 40(4): 107-115. DOI: 10.16562/j.cnki.0256-1492.2019081701

大洋蛇纹岩化无机成因甲烷水合物稳定带底界模拟

Simulation of bottom boundaries of abiotic methane hydrate stability zone in some marine serpentinization areas

  • 摘要: 随着深海调查研究的不断深入,发现大洋基性和超基性岩与水相互作用可发生蛇纹岩化作用产生无机成因甲烷等烃类气体,可能在大洋区海底形成水合物。为评估大洋蛇纹岩化无机成因甲烷水合物生成热力学条件及水合物稳定带分布特征,本文利用实测的原位温度、水深等条件,结合甲烷水合物-水-游离气三相平衡温压条件,计算了马里亚纳弧前蛇纹岩泥火山、北大西洋Fram海峡超慢速扩张脊和Lost City慢速扩张脊3个不同地质构造环境的蛇纹岩化发育的大洋区海底环境甲烷水合物稳定带底界,并对其水合物发育潜力进行了评估。研究表明马里亚纳弧前蛇纹岩泥火山和北大西洋Fram海峡超慢速扩张脊满足天然气水合物发育的热力学条件,可能发育有甲烷水合物,相应的水合物稳定带底界深度分别约为858~2 515和153~232 mbsf。大西洋Lost City喷口附近发育甲烷水合物可能性较小。

     

    Abstract: Fluids circulating through active serpentinization systems are often highly enriched in methane. When the fluid enriched in abiotic methane migrates upward, gas hydrate could form if there occur suitable thermodynamic conditions. In order to investigate the thermodynamic conditions of the stability zone of abiotic methane hydrate in marine serpentinization areas, we calculated the depth of the bottom boundaries of gas hydrate stability zone in three distinctive serpentinization areas, i.e. the Mariana forearc serpentinized mud volcanos, the Fram strait (an ultraslow- spreading ridge) and the Lost City (a slow spreading ridge). Our results show that the thermodynamic conditions are satisfied for forming the hydrate stability zone in the areas of Mariana forearc serpentinite mud volcanos and the ultraslow-spreading ridge at the Fram Strait. Calculation shows the depth of the bottom boundaries of gas hydrate stability zone is around 858~2515 mbsf at Mariana forearc mud volcano area and 153~232 mbsf at the Fram Strait. However, the temperature of vent fluids found at the Lost City is relative higher than needed for the formation of gas hydrate stability zone.

     

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