Mineralogical diversity in Lake Pavin: connections with water column chemistry and biomineralization processes | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

Twitter

Aller au compte twitter

  Mineralogical diversity in Lake Pavin: connections with water column chemistry and biomineralization processes

Type de publication:

Journal Article

Source:

Minerals (2016)

Résumé:

As biominerals are good tracers of microbial interactions with the environment, they may provide signatures of microbial evolution and paleoenvironmental conditions. Since modern analogues of past environments help defining proxies and biosignatures, we explored microbe mineral interactions in the water column of a maar lake, located in France: Lake Pavin. This lake is considered as a potential Precambrian ocean analogue, as it is ferruginous and meromictic, i.e. stratified with a superficial O2-rich layer (mixolimnion) and a deeper permanently anoxic layer (monimolimnion). We combined bulk chemical analyses of dissolved and particulate matter in combination with electron microscopy analyses of the particulate matter at different depths along the water column. The mineralogy changed along with water chemistry, and most of the minerals were intimately associated with microorganisms. Evolution of the redox conditions with depth leads to the successive precipitation of silica and carbonates, Mn-bearing, Fe-bearing and S-containing phases, with a predominance of phosphates in the monimolimnion. This scheme parallels the currently assessed changes of microbial diversity with depth. The present results corroborate previous studies that suggested a strong influence of microbial activity on mineralogical diversity through extracellular and intracellular biomineralization.