Shallow-Marine Carbonates - Trace Fossils as Indicators of Sedimentary Environments - page 681

Chapter 23
Shallow-Marine Carbonates
Dirk Knaust, * ,1 H. Allen Curran † and Andrei V. Dronov ‡
*Statoil ASA, Stavanger, Norway, † Department of Geosciences, Smith College, Northampton,
Massachusetts, USA, ‡ Russian Academy of Sciences, Geological Institute, Moscow, Russia
1 Corresponding author: e-mail: [e-mail]
1. INTRODUCTION
Carbonates comprise only 20-25% of the total volume of all sedimentary rocks
( Boggs, 2009 ). This fact is reflected in the relatively small number of ichnolo-
gical studies of carbonates compared with siliciclastics, although other aspects
(such as sedimentology or diagenesis) are roughly equally covered. Given the
importance of carbonates as oil and gas reservoirs and aquifers (about 50% of
the world's total proven hydrocarbon reserves are held in carbonate reservoirs),
the ichnology of carbonate sedimentary systems has much potential for future
investigations.
This chapter deals with the ichnology of shallow-marine carbonates, ranging
from marginal-marine (peritidal) environments to the shelf. Trace fossils in car-
bonate rocks were previously reviewed by Kennedy (1975) and Ekdale et al.
(1984) , and ichnocoenoses specific to Quaternary, Bahamian-style carbonate
environments by Curran (1994, 2007) .
A review of literature with significant studies on the ichnology of shallow-
marine carbonates shows an unequal representation of different time periods
(studies focused solely on individual ichnotaxa are disregarded). Precambrian
to Cambrian systems with their microbial mat-related, early bilaterian lifestyles
are generally poorly covered (e.g., Weber et al., 2007 ). In the Phanerozoic,
Paleozoic carbonate ichnology is strongly underrepresented, whereas the Meso-
zoic is relatively well documented. This is especially true for the Silurian to
Permian (e.g., Archer, 1984; Knaust, 2009, 2010a; Narbonne, 1984 ), compared
to the relatively intensively studied Ordovician (e.g., Dronov et al., 2002; Fei
and Zhang, 2002; Osgood, 1970; Pickerill and Forbes, 1979; Pickerill et al.,
1984 ). In the Mesozoic, several studies deal with the ichnology of Triassic car-
bonate platforms and ramps (e.g., Diedrich, 2008 and references therein;
Knaust, 1998, 2007a,b, 2009, 2010a,b; Knaust and Costamagna, 2012;
Rodr ´ guez-Tovar et al., 2007; Twitchett and Wignall, 1996 ), but many are
dedicated to the Jurassic (e.g., Avanzini et al., 1997; de Gibert, 1996; de Gibert