气候变化领域集成服务门户(CCPortal): Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard

CCPortal

DOI	10.1029/2020JB019468
	Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard
	Riedel M.; Villinger H.; Freudenthal T.; Pape T.; Bünz S.; Bohrmann G.
发表日期	2020
ISSN	21699313
卷号	125 期号:12
英文摘要	The Svalbard margin represents one of the northernmost gas hydrate provinces worldwide. Vestnesa Ridge (VR) and Svyatogor Ridge (SR) west of Svalbard are two prominent sediment drifts showing abundant pockmarks and sites of seismic chimney structures. Some of these sites at VR are associated with active gas venting and were the focus of drilling and coring with the seafloor-deployed MARUM-MeBo70 rig. Understanding the nature of fluid migration and gas hydrate distribution requires (among other parameters) knowledge of the thermal regime and in situ gas and pore fluid composition. In situ temperature data were obtained downhole at a reference site at VR defining a geothermal gradient of ~78 mK m−1 (heat flow ~95 mW m−2). Additional heat probe data were obtained to describe the thermal regime of the pockmarks. The highest heat flow values were systematically seen within pockmark depressions and were uncorrelated to gas venting occurrences. Heat flow within pockmarks is typically ~20 mW m−2 higher than outside pockmarks. Using the downhole temperature data and gas compositions from drilling we model the regional base of the gas hydrate stability zone (BGHSZ). Thermal modeling including topographic effects suggest a BGHSZ up to 40 m deeper than estimated from seismic data. Uncertainties in sediment properties (velocity and thermal conductivity) are only partially explaining the mismatch. Capillary effects due to small sediment grain sizes may shift the free gas occurrence above the equilibrium BGHSZ. Changes in gas composition or pore fluid salinity at greater depth may also explain the discrepancy in observed and modeled BGHSZ. © 2020. The Authors.
英文关键词	gas hydrate; heat flow; MeBo drilling; pockmark; Svalbard margin
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/187446
作者单位	GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany; Department of Geosciences, University of Bremen, Bremen, Germany; MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany; Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geology, UiT The Arctic University of Norway, Tromsø, Norway
推荐引用方式 GB/T 7714	Riedel M.,Villinger H.,Freudenthal T.,et al. Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard[J],2020,125(12).
APA	Riedel M.,Villinger H.,Freudenthal T.,Pape T.,Bünz S.,&Bohrmann G..(2020).Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard.Journal of Geophysical Research: Solid Earth,125(12).
MLA	Riedel M.,et al."Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard".Journal of Geophysical Research: Solid Earth 125.12(2020).