Geological Society of America

T206 Records of Early Diagenesis in Modern and Ancient Sediments

Thursday, 29 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

IRON CYCLING IN ARCTIC METHANE SEEPS

Paper number: T206-11
Program: Technical Sessions
Time: 4:00 PM – 4:10 PM

Authors

Wei-li Hong Presenting Author
Stockholm University, Stockholm
Wei-li Hong Presenting Author
Geological Survey of Norway, Trondheim, N/A
Wei-li Hong Presenting Author
Stockholm University, Stockholm, Södermanland and Uppland
Pauline Latour
University of Tasmania, Tasmania
Simone Sauer
Université de Bretagne Occidentale, Plouzané
Arunima Sen
Nord University, Bodø, Bodø, Bodø
William Gilhooly
Indiana University-Purdue University Indianapolis, Indianapolis, IN
Aivo Lepland
Geological Survey of Norway, Trondheim, Sør-Trøndelag county
Fotios Fouskas
Indiana University-Purdue University Indianapolis, Indianapolis, IN

Abstract

Anoxic marine sediments contribute a significant amount of dissolved iron (Fe²⁺⁾ to the ocean which is crucial for the global carbon cycle. Here, we investigate iron cycling in four Arctic cold seeps where sediments are anoxic and sulfidic due to the high rates of methane-fueled sulfate reduction. We estimated Fe²⁺ diffusive fluxes towards the oxic sediment layer to be in the range of 0.8 to 138.7 μmole/m²/day and Fe²⁺ fluxes across the sediment-water interface to be in the range of 0.3 to 102.2 μmole/m²/day. Such variable fluxes cannot be explained by Fe²⁺ production from organic matter–coupled dissimilatory reduction alone. We propose that the reduction of dissolved and complexed Fe³⁺ as well as the rapid formation of iron sulfide minerals are the most important reactions regulating the fluxes of Fe²⁺ in these cold seeps. By comparing seafloor visual observations with subsurface pore fluid composition, we demonstrate how the joint cycling of iron and sulfur determines the distribution of chemosynthesis-based biota.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-353665

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