02426nas a2200241   4500008004100000022001400041245010000055210006900155260001200224490000800236520166500244653001501909653001701924653002901941653002401970653002201994653001902016100002202035700002202057700001502079700002102094856006902115       2025                        eng d  a2169-895300aMorphology and distribution of bubble-supported microbial mats from ice-covered Antarctic lakes0 aMorphology and distribution of bubblesupported microbial mats fr  c03/20250 v1303 a<p>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 &ldquo;liftoff mats.&rdquo; 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.</p>10aAntarctica10abiosediments10abubble-driven morphology10agas-supersaturation10aice-covered lakes10amicrobial mats1 aJuarez-Rivera, M.1 aMackey, Tyler, J.1 aHawes, Ian1 aSumner, Dawn, Y.  uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024JG008516