{"id":284,"date":"2015-12-28T02:09:21","date_gmt":"2015-12-28T02:09:21","guid":{"rendered":"http:\/\/192.168.99.100:8080\/award\/identifying-the-controls-on-biological-activity-in-serpentinites\/"},"modified":"2019-08-12T10:31:06","modified_gmt":"2019-08-12T17:31:06","slug":"identifying-the-controls-on-biological-activity-in-serpentinites","status":"publish","type":"award","link":"https:\/\/www.darkenergybiosphere.org\/award\/identifying-the-controls-on-biological-activity-in-serpentinites\/","title":{"rendered":"Identifying the controls on biological activity in serpentinites"},"content":{"rendered":"<p>Serpentinization \u2013 the hydrothermal alteration of ultramafic rocks \u2013 is a unique\u00a0mineralogical process that results in H<sub>2<\/sub> and CH<sub>4<\/sub> &#8211; rich fluids that can support microbial\u00a0communities. Using a combination of petrographic observations, bulk rock and <i>in-situ<\/i> sulfur\u00a0isotope signatures of variably serpentinized peridotites from four different geotectonic\u00a0environments we provide new constraints on the factors that support microbial activity. The\u00a0studied samples overall suggest that redox conditions reflected by the presence of pyrite and\u00a0pyrrhotite represent the fluid chemistry that favors microbial activity. This fluid chemistry,\u00a0i.e., the prevailing hydrogen and sulfur fugacities of the fluid, are thereby correlated to high\u00a0water-rock ratios and increased incorporation of seawater-derived species such as sulfate and\u00a0carbonate. These species serve as major energy sources of microbial activity. In contrast,\u00a0highly reducing conditions and limited fluid input limits or even prevents microbial activity\u00a0within serpentinites due to insufficient availability of these species. Interaction with carbonate\u00a0and sulfate-bearing meteoric waters is likely an essential process that supports microbial\u00a0activity in continental serpentinization environments. Overall, this study shows that apart\u00a0from fluid temperatures being within the limits of life, the fluid chemistry (redox conditions\u00a0and availability of e.g. carbonate and sulfate) are the primary factors that control the presence\u00a0or absence of microbial communities within serpentinizing peridotites. This study highlights\u00a0the importance of combining bulk rock and <i>in-situ<\/i> stable isotope data with petrographic and\u00a0mineralogical observations in order to better constraint the presence of microbial\u00a0communities within the subsurface of peridotite-hosted hydrothermal systems.<\/p>\n","protected":false},"template":"","meta":[],"award_type":[11],"_links":{"self":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/awards\/284"}],"collection":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/awards"}],"about":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/types\/award"}],"wp:attachment":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/media?parent=284"}],"wp:term":[{"taxonomy":"award_type","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/award_type?post=284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}