气候变化领域集成服务门户(CCPortal): Origin and Transformation of Light Hydrocarbons Ascending at an Active Pockmark on Vestnesa Ridge, Arctic Ocean

CCPortal

DOI	10.1029/2018JB016679
	Origin and Transformation of Light Hydrocarbons Ascending at an Active Pockmark on Vestnesa Ridge, Arctic Ocean
	Pape T.; Bünz S.; Hong W.-L.; Torres M.E.; Riedel M.; Panieri G.; Lepland A.; Hsu C.-W.; Wintersteller P.; Wallmann K.; Schmidt C.; Yao H.; Bohrmann G.
发表日期	2020
ISSN	21699313
卷号	125 期号:1
英文摘要	We report on the geochemistry of hydrocarbons and pore waters down to 62.5 mbsf, collected by drilling with the MARUM-MeBo70 and by gravity coring at the Lunde pockmark in the Vestnesa Ridge. Our data document the origin and transformations of volatiles feeding gas emissions previously documented in this region. Gas hydrates are present where a fracture network beneath the pockmark focusses migration of thermogenic hydrocarbons characterized by their C1/C2+ and stable isotopic compositions (δ2H-CH4, δ13C-CH4). Measured geothermal gradients (~80 °C/km) and known formation temperatures (>70 °C) suggest that those hydrocarbons are formed at depths >800 mbsf. A combined analytical/modeling approach, including concentration and isotopic mass balances, reveals that pockmark sediments experience diffuse migration of thermogenic hydrocarbons. However, at sites without channeled flow this appears to be limited to depths >~50 mbsf. At all sites we document a contribution of microbial methanogenesis to the overall carbon cycle that includes a component of secondary carbonate reduction—that is, reduction of dissolved inorganic carbon generated by anaerobic oxidation of methane in the uppermost methanogenic zone. Anaerobic oxidation of methane and carbonate reduction rates are spatially variable within the pockmark and are highest at high-flux sites. These reactions are revealed by 13C depletions of dissolved inorganic carbon at the sulfate-methane interface at all sites. However, 13C depletions of CH4 are only observed at the low methane flux sites because changes in the isotopic composition of the overall methane pool are masked at high-flux sites. 13C depletions of total organic carbon suggest that at seeps sites, methane-derived carbon is incorporated into de novo synthesized biomass. ©2019. The Authors.
英文关键词	gas hydrate; isotopic mass balance; MeBo drilling; methane; pockmark; pressure coring
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/188047
作者单位	MARUM—Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany; Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT—The Arctic University of Norway, Tromsø, Norway; Geological Survey of Norway, Trondheim, Norway; College of Earth Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States; GEOMAR—Helmholtz Centre for Ocean Research, Kiel, Germany
推荐引用方式 GB/T 7714	Pape T.,Bünz S.,Hong W.-L.,et al. Origin and Transformation of Light Hydrocarbons Ascending at an Active Pockmark on Vestnesa Ridge, Arctic Ocean[J],2020,125(1).
APA	Pape T..,Bünz S..,Hong W.-L..,Torres M.E..,Riedel M..,...&Bohrmann G..(2020).Origin and Transformation of Light Hydrocarbons Ascending at an Active Pockmark on Vestnesa Ridge, Arctic Ocean.Journal of Geophysical Research: Solid Earth,125(1).
MLA	Pape T.,et al."Origin and Transformation of Light Hydrocarbons Ascending at an Active Pockmark on Vestnesa Ridge, Arctic Ocean".Journal of Geophysical Research: Solid Earth 125.1(2020).