气候变化领域集成服务门户(CCPortal): Constraining the formation of authigenic carbonates in a seepage-affected cold-water coral mound by lipid biomarkers

CCPortal

DOI	10.1111/gbi.12373
	Constraining the formation of authigenic carbonates in a seepage-affected cold-water coral mound by lipid biomarkers
	Feenstra E.J.; Birgel D.; Heindel K.; Wehrmann L.M.; Jaramillo-Vogel D.; Grobéty B.; Frank N.; Hancock L.G.; Van Rooij D.; Peckmann J.; Foubert A.
发表日期	2020
ISSN	14724677
起始页码	185
结束页码	206
卷号	18 期号:2
英文摘要	Cold-water coral (CWC) mounds are build-ups comprised of coral-dominated intervals alternating with a mixed carbonate-siliciclastic matrix. At some locations, CWC mounds are influenced by methane seepage, but the impact of methane on CWC mounds is poorly understood. To constrain the potential impact of methane on CWC mound growth, lipid biomarker investigations were combined with mineralogical and petrographic analyses to investigate the anaerobic oxidation of methane (AOM) and authigenic carbonate formation in sediment from a seep-affected CWC mound in the Gulf of Cadiz. The occurrence of AOM was confirmed by characteristic lipids found within a semi-lithified zone (SLZ) consisting of authigenic aragonite, high-magnesium calcite and calcium-excess dolomite. The formation of high-Mg calcite is attributed to AOM, acting as a lithifying agent. Aragonite is only a minor phase. Ca-excess dolomite in the SLZ and upper parts may be formed by organoclastic sulphate reduction, favouring precipitation by increased alkalinity. The AOM biomarkers in the SLZ include isoprenoid-based archaeal membrane lipids, such as abundant glycerol dibiphytanyl glycerol tetraethers (GDGTs) dominated by GDGT-2. The δ13C values of GDGT-2, measured as ether-cleaved monocyclic biphytanes, are as low as −100‰ versus V-PDB. Further, bacterial dialkyl glycerol diethers with two anteiso-C15 alkyl chains and δ13C values of −81‰ are interpreted as biomarkers of sulphate-reducing bacteria. The lipid biomarker signatures and mineralogical patterns suggest that anaerobic methane-oxidizing archaea of the ANME-1 group thrived in the subsurface at times of slow and diffusive methane seepage. Petrographic analyses revealed that the SLZ was exhumed at some point (e.g. signs of bioerosion of the semi-lithified sediment), providing a hard substrate for CWC larval settlement. In addition, this work reveals that AOM-induced semi-lithification likely played a role in mound stabilization. Lipid biomarker analysis proves to be a powerful tool to disentangle early diagenetic processes induced by microbial metabolisms. © 2019 John Wiley & Sons Ltd
关键词	anoxic conditions authigenesis biomarker calcite carbonate system cold water coral reef dolomite lipid oxidation petrography seepage sulfate Atlantic Ocean Gulf of Cadiz Anthozoa Archaea Bacteria (microorganisms)
语种	英语
来源机构	Geobiology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/133194
推荐引用方式 GB/T 7714	Feenstra E.J.,Birgel D.,Heindel K.,et al. Constraining the formation of authigenic carbonates in a seepage-affected cold-water coral mound by lipid biomarkers[J]. Geobiology,2020,18(2).
APA	Feenstra E.J..,Birgel D..,Heindel K..,Wehrmann L.M..,Jaramillo-Vogel D..,...&Foubert A..(2020).Constraining the formation of authigenic carbonates in a seepage-affected cold-water coral mound by lipid biomarkers.,18(2).
MLA	Feenstra E.J.,et al."Constraining the formation of authigenic carbonates in a seepage-affected cold-water coral mound by lipid biomarkers".18.2(2020).