Biomat-Related Lifestyles in the Precambrian

Remarkable preservation of microbial mats in Neoproterozoic siliciclastic settings: Implications for Ediacaran taphonomic models

“…1, Seilacher, 1956;Brasier, 1979;Brasier, 1992;Seilacher & Pflüger 1994;Droser et al, 1999;Hagadorn & Bottjer, 1999;McIlroy & Logan, 1999;Bottjer et al, 2000;Droser et al, 2002a;Jensen, 2003;Droser et al, 2004;Jensen et al, 2005). In summary, it should be noted that without significant bioturbation (McIlroy & Logan, 1999), and in the presence of widespread benthic microbial mats (Seilacher & Pflüger, 1994;Seilacher, 1999), the aerobic mixed layer would have been limited to the maximum extent of solute diffusion beneath a sharp sediment-water interface and anoxic conditions could have been present just millimetres beneath the sediment-water interface (e.g. Gehling, 1999;Bottjer et al, 2000;McIlroy & Logan, 1999;Bailey et al, 2006).…”

“…In the Precambrian ocean, however, intensive macrofaunal bioturbation is believed to have been universally insignificant or absent (e.g. Droser et al, 1999;McIlroy & Logan, 1999;Seilacher, 1999;Bottjer et al, 2000;Droser et al, 2002a;Jensen, 2003;Droser et al, 2004;Jensen et al, 2005), regardless of the rates of sedimentation or C org supply. A consequence of a shallower sediment mixed layer in the Ediacaran Period, would therefore appear to be that carbonaceous material would typically have undergone less microbial degradation by the time that it reached the potential zones of preservation (mineralization) within the sediment (e.g.…”

“…These biological changes not only had major and irreversible effects on benthic palaeobiology and palaeoecology (Brasier, 1992;Brasier et al, 1994;Seilacher & Pflüger, 1994;Hagadorn & Bottjer, 1999;Seilacher, 1999;Bottjer et al, 2000;Droser et al, 2002a;Dornbos et al, 2004;Droser et al, 2004;Dornbos et al, 2005;Jensen et al, 2005;Droser et al, 2006) but also on ocean and sediment biogeochemistry (Brasier 1992;Seilacher & Pflüger, 1994;Gehling, 1999;McIlroy & Logan, 1999;Shields, 2002;Droser et al, 2004;Gehling et al, 2005;Bailey et al, 2006). They also appear to have led to a fundamental shift in the nature of fossil preservation (taphonomy) across this interval (e.g.…”

“…Since that time, considerable strides have been made in our understanding of the changes in both the physical and the chemical nature of the uppermost layers of marine sediments, owing to these coeval explosions of bioturbation and biomineralization (e.g. Crimes, 1992;Seilacher & Pflüger, 1994;Droser et al, 1999;Seilacher, 1999;Bottjer et al, 2000;Droser et al, 2002a;Jensen, 2003;Bengtson, 2004;Dornbos et al, 2004;Droser et al, 2004;Seilacher et al, 2005).…”

“…These predictions are examined by means of a review concerning the distinctive phenomenon of bedding plane wrinkle structures or MISS (sensu Noffke et al, 2001), which are often used to infer the presence of widespread microbial mats (biofilms) on the Ediacaran seafloor (e.g. Seilacher & Pflüger, 1994;Seilacher, 1999;Gerdes et al, 2000;Noffke et al, 2001;2002;Noffke, 2009 this volume). Also considered is the emerging evidence for the preservation of microbial components of the mats themselves, in a variety of taphonomic modes (e.g.…”