A Numerical Model to Estimate the Effects of Variable Sedimentation Rates on Methane Hydrate Formation—Application to the ODP Site 997 on Blake Ridge, Southeastern North American Continental Margin
A Numerical Model to Estimate the Effects of Variable Sedimentation Rates on Methane Hydrate Formation—Application to the ODP Site 997 on Blake Ridge, Southeastern North American Continental Margin
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估算可变沉积速率对甲烷水合物形成影响的数值模型——在北美大陆边缘东南部布莱克海岭 ODP 997 站点的应用
DOI：
10.1029/2019jb018851
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发表时间：
2020-06
期刊：
影响因子：
--
通讯作者：
Duofu Chen
中科院分区：
文献类型：
--
作者：
Zihan Zheng;Yuncheng Cao;Wenyue Xu;Duofu Chen
由于地质时间尺度上不断变化的构造过程，沉积和埋藏速度在大陆坡可能有很大差异。这种变化可能会影响甲烷在沉积物中的迁移，表现为孔隙水通量、甲烷生成、甲烷扩散和水合物稳定带（HSZ）中水合物的迁移，进而影响海底沉积物中水合物的聚集。以往的模型大多假设了恒定的沉积速率，因此可能导致对HSZ内水合物总量的不准确估计。在这项研究中，我们开发了一个水合物积累模型，能够处理多个沉积阶段。选择ODP 164航次997站位，研究其沉积速率变化的意义，该站位的数据表明其近期经历了四个不同速率的沉积阶段。我们研究了不同的沉积速率对水合物积累的影响，考虑到沉积物压实，原位甲烷生成，以及成分和组分的运输过程。模拟结果表明，997站点水合物的积累历史具有增加、减少、然后增加的顺序，直到现在。目前，水合物存款已累积到8.30 × 104 mol/m2，在HSZ的底部附近的平均水合物饱和度为6.3%，这与文献中公布的估计基本一致。在站点997的水合物的积累受到可变的沉积速率的显著影响，近一半的水合物存款积累在过去的2.5百万年。
Sedimentation and burial rate can vary considerably at continental slopes, due to constantly changing tectonic processes on the geological timescale. This variation may affect the transport of methane in sediment, as manifested in the change of pore water flux, methanogenesis, methane diffusion and hydrate removal from hydrate stability zone (HSZ) and further affect the accumulation of hydrate in submarine sediments. Most of previous models assumed a constant sedimentation rate and thus may result in inaccurate estimates of total amount of hydrate within the HSZ. In this study, we developed a hydrate accumulation model that is capable of handling multiple sedimentation stages. Site 997 of ODP Leg 164, with data indicating its recent history of four sedimentation stages of different rates, is chosen to investigate the significance of sedimentation rate variation experienced at this location. We examined the effect of varying sedimentation rates on hydrate accumulation by taking in consideration sediment compaction, in situ methanogenesis, and composition and component transport processes. Simulation results suggest that the history of hydrate accumulation at Site 997 is characterized by a sequence of increase, decrease, and then increase till the present day. At present, the hydrate deposit has accumulated to 8.30 × 104 mol/m2, and the average hydrate saturation near the base of the HSZ is 6.3%, which is in general agreement with published estimates in the literature. The accumulation of hydrate at Site 997 was significantly affected by variable sedimentation rates, and nearly one half of the hydrate deposit was accumulated during the last 2.5 Myr.
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影响因子：
5.3
作者：
Haacke, R. Ross;Westbrook, Graham K.;Hyndman, Roy D.
通讯作者：
Hyndman, Roy D.
影响因子：
--
作者：
Duofu Chen;L. Cathles
通讯作者：
Duofu Chen;L. Cathles
影响因子：
7.4
作者：
P. Licence
通讯作者：
P. Licence
影响因子：
--
作者：
A. Rempel
通讯作者：
A. Rempel
影响因子：
4.9
作者：
E. Piñero;M. Marquardt;C. Hensen;M. Haeckel;K. Wallmann
通讯作者：
E. Piñero;M. Marquardt;C. Hensen;M. Haeckel;K. Wallmann