Migration of the sulphate–methane reaction zone in marine sediments of the Sea of Marmara—can this mechanism be tectonically induced?

Sulphate concentration profiles with non-constant gradients are reported from porewater samples in continental margin sediments. Recent results on a sediment core from the Ganos Fault in the Sea of Marmara revealed a porewater pattern with two gradients. Comparisons with the respective methane concentrations show the position of a sulphate–methane reaction zone (SMRZ) within the sediment column. Methane emanations from the seafloor as observed at other locations along the deeper Ganos Fault indicate the SMRZ as a transient system. A computer model based on an unsteady process estimates the starting time of the methane rise between 1096 and 907 years before present. Within this time period, one remarkable earthquake occurred in the direct vicinity of our study area in the year 1063 A.D. We suggest this could have opened the pathways for the ascending methane front.