Microbial Alteration of Carbonate Archives
Marine biogenic carbonates are comprehensive archives of paleoenvironmental conditions. The main environmental variables that can be deduced from carbonate elemental- and isotopic composition are past sea-surface temperature (SST), salinity and related ocean circulation patterns, and trace element concentration. These parameters are crucial to understand paleo-ocean and atmospheric conditions, and to furthermore allow for interpolation to future environmental variables. However, the respective signals in carbonates can be biased by diagenetic alteration, and the abiotic processes involved in the diagenetic processes are being thoroughly investigated. A less considered, but potentially profound (co-) factor in earliest diagenesis are benthic microbial communities. Microbe-mineral interaction is known to shape the earth´s lithosphere through carbonate formation, dissolution, and geochemical alteration over geological timescales. However, the benthic microbial impact on marine carbonate archives after post mortem deposition in shallow sediments has rarely been included in diagenetic concepts so far. The present study investigates the carbonate-alteration potential of benthic microbe-mineral interaction during earliest diagenesis, thereby elucidating the underlying mechanisms - and the related consequences for carbonate-archive interpretation.