<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Sumner, Dawn Y.</style></author><author><style face="normal" font="default" size="100%">Ian Hawes</style></author><author><style face="normal" font="default" size="100%">Mackey, Tyler J.</style></author><author><style face="normal" font="default" size="100%">Jungblut, Anne D.</style></author><author><style face="normal" font="default" size="100%">Peter T. Doran</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Antarctic microbial mats: A modern analog for Archean lacustrine oxygen oases</style></title><secondary-title><style face="normal" font="default" size="100%">Geology</style></secondary-title><short-title><style face="normal" font="default" size="100%">Geology</style></short-title></titles><dates><year><style  face="normal" font="default" size="100%">2015</style></year><pub-dates><date><style  face="normal" font="default" size="100%">10/2015</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://geology.gsapubs.org/lookup/doi/10.1130/G36966.1</style></url></web-urls></urls><pages><style face="normal" font="default" size="100%">G36966.1</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;div class=&quot;page&quot; title=&quot;Page 1&quot;&gt;&lt;div class=&quot;section&quot;&gt;&lt;div class=&quot;layoutArea&quot;&gt;&lt;div class=&quot;column&quot;&gt;&lt;p&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;The evolution of oxygenic photosynthesis was the most important geochemical event in &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;Earth history, causing the Great Oxidation Event (GOE) ~2.4 b.y. ago. However, evidence is mixed as to whether O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;production occurred locally as much as 2.8 b.y. ago, creating O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;oases, or initiated just prior to the GOE. The biogeochemical dynamics of possible O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;oases have been poorly constrained due to the absence of modern analogs. However, cyanobacteria in microbial mats in a perennially anoxic region of Lake Fryxell, Antarctica, create a 1&amp;ndash;2 mm O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2&lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;-containing layer in the upper mat during summer, providing the first known modern analog for formation of benthic O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;oases. In Lake Fryxell, benthic cyanobacteria are present below the oxycline in the lake. Mat photosynthesis rates were slow due to low photon flux rate (1&amp;ndash;2 μmol m&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Symbol'; vertical-align: 3.000000pt&quot;&gt;-&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: 3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;s&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Symbol'; vertical-align: 3.000000pt&quot;&gt;-&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: 3.000000pt&quot;&gt;1&lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;) under thick ice cover, but photosynthetic O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;production was sufficient to sustain up to 50 μmol O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;L&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Symbol'; vertical-align: 3.000000pt&quot;&gt;-&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: 3.000000pt&quot;&gt;1&lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;, sandwiched between anoxic overlying water and anoxic sedi- ments. We hypothesize that Archean cyanobacteria could have similarly created O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;oases in benthic mats prior to the GOE. Analogous mats may have been at least partly responsible for geological evidence of oxidative weathering prior to the GOE, and habitats such as Lake Fryxell provide natural laboratories where the impact of benthic O&lt;/span&gt;&lt;span style=&quot;font-size: 5.000000pt; font-family: 'Times'; font-weight: 700; vertical-align: -3.000000pt&quot;&gt;2 &lt;/span&gt;&lt;span style=&quot;font-size: 9.000000pt; font-family: 'Times'; font-weight: 700&quot;&gt;oases on biogeochemical signatures can be investigated.&amp;nbsp;&lt;/span&gt;&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;</style></abstract></record></records></xml>