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Abstract Gas bubbles directly influence the macromorphology of benthic microbial mats resulting in preservable biosedimentary structures. This study characterizes the morphology and distribution of microbial mats growing in gas‐supersaturated, perennially ice‐covered lakes Fryxell, Joyce, and Hoare of the McMurdo Dry Valleys of Antarctica. Photosynthetic benthic mats within the gas‐supersaturated zone trap oxygen‐rich bubbles and become buoyant, tearing off the bottom as “liftoff mats.” These liftoff mats form a succession of morphologies starting with bubble‐induced deformation of flat mats into tent, ridge, and finger liftoff mat. With progressive deformation, mats tear, forming sheet liftoff, while multiple cycles of deformation and tearing transform sheet into strip liftoff. Some mats detach from the substrate and float to the underside of the ice. The depth range of the liftoff zone has varied over time at each lake. Downslope expansion of bubble formation brings previously bubble‐free, deep‐water pinnacle mats into the liftoff zone. When the liftoff zone shallows, liftoff mats at the deeper end deflate and can become scaffolding for additional mat growth. The superposition and relative orientation of liftoff and pinnacle mats can be used to track the maximum depth of the liftoff zone and changes in gas saturation state in these lakes through time. Our results demonstrate that gas bubbles, even when they are transitory, can exert a significant impact on the morphology of microbial mats at larger scales. This provides a way to identify similar structures and gas supersaturated environments in the biosedimentary record.
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Lake Fryxell 2022-2023 benthic microbial mat thickness and number of laminae
This dataset contains measurements of microbial mat thickness and number of laminae from Lake Fryxell, McMurdo Dry Valleys, Antarctica. Holes were melted through the ice cover of Lake Fryxell, which allowed tethered divers to collect benthic microbial mats (non-liftoff and liftoff) and microbial mats at the ice-water interface (float mats). Benthic non-liftoff and liftoff mat samples were collected from 4.3 m (n=4), 6.1 m (n=4), and 7.9 m (n=4) depths. Float mats were collected from the ice-water interface above 4.3 m (n=4), 6.1 m (n=4), and 7.9 m (n=5) depths. The mats were dissected along vertical cross sections in the field to measure mat thickness and number of laminae. Additional funding for this work was provided by the NASA Solar System Workings Program (Award #80NSSC22K0709).
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- Award ID(s):
- 2336354
- PAR ID:
- 10574895
- Publisher / Repository:
- U.S. Antarctic Program (USAP) Data Center
- Date Published:
- Subject(s) / Keyword(s):
- Cryosphere Laminae Microbial Mat Thickness
- Format(s):
- Medium: X Size: 3.1 kB Other: csv
- Size(s):
- 3.1 kB
- Location:
- Antarctica; Antarctica; Dry Valleys; Lake Fryxell; (Latitude:-77.6078; Longitude:163.1146)
- Right(s):
- Creative Commons Attribution 4.0 International
- Institution:
- University of New Mexico
- Sponsoring Org:
- National Science Foundation
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