Microrhombic calcite crystals, which form the frame of microporosity in most Middle Eastern carbonate reservoirs, formed at temperatures of 60°C
to 80°C and a burial depth in excess of 1km (Vahrenkamp et al., 2014; Swart et al., 2016). Since there are possibilities by some initial experiments
on the ability of microbes to be alive and perform diagenetic alterations at elevated temperatures and pressure (Daffonchio and co-workers,
unpublished data; see preliminary data below), we propose to investigate whether microbes are involved in the generation of those microrhombic
crystals through microbial diagenesis of previous micritized sediments.