Geomicrobiology of the Kraubath magnesite deposit

Ser pentinization is a geologic process that involves t he transformation of iron- and magnesium-rich m inerals of t h e oceanic crust by water t o so-called serpentinites. Serpentinites are rocks com posed of m inerals of the ser pentine-group that include Lizardite, Antigorite, and Chrysotile. Du ring t his transformation process m olecular h y drogen (H2) is g enerated t hat can be used by archaea as an energy source for their metabolism . Archaea are m icroorganism s that r epresent on e of t he three dom ains of life, and are the only known or ganism s on Ea rth that pr oduce methane. Although serpentinization m ainly occurs a t mid-ocean ridges on the ocean floor t oday, it is a lso kn own within r ocks of the oceanic crust t hat are exposed on land. Here, the transformation of t hese crustal rocks pr oceeds by circulating groundwaters, whose highly alkaline com position m ay lead t o the formation of carbonate m inerals such a s magnesite (MgCO 3). The formation of m agnesite a t low t emperatures is a t the forefront of r esearch t oday due to its relevance for geobiological studies and, in particular, its application for carbon capture and storage st r ategies. Because the formation of m agnesite usually occurs at h igher t emperatures a bov e 1 00C, its low - t em perature (<80C) formation is restricted t o specific environments that include soda lakes and sabkhas, but also a lkaline springs a ssociated with on shore serpentinization of oceanic crustal rocks. The Kraubath com plex in the ea st ern Alps r epresents on e of t he type localities for m agnesite deposits, and is known for its high purity and excellent qu a lity a s a resource worldwide. However, the formation mechanism s of the Kraubath m agnesites are n ot well known so fa r , and a m icrobiological formation cannot be excluded. This project aims t o investiga te if m ethane-producing a r chaea facilitate and accelerate the formation of m agnesite a t low t emperatures, and if they are key organisms in the for m ation of low -temperature magnesite deposits. This interdisciplinary project will be conducted in cooperation with n a tional and international r esearch groups in the fields of g eochemistry, mineralogy, a nd m icrobiology.