Carbonate Aquifers - Trace Fossils as Indicators of Sedimentary Environments - page 841

Chapter 28
Carbonate Aquifers
Kevin J. Cunningham, * ,1 Michael C. Sukop † and H. Allen Curran ‡
*U.S. Geological Survey, Davie, Florida, USA, † Department of Earth and Environment, Florida
International University, Miami, Florida, USA, ‡ Department of Geosciences, Smith College,
Northampton, Massachusetts, USA
1 Corresponding author: e-mail: [e-mail]
1. INTRODUCTION
Recent research has demonstrated that trace fossils and their associated ichnofab-
rics can have an important impact on the fluid-flow properties of hydrocarbon
reservoirs and groundwater aquifers. Ichnology, and specifically ichnofabric
analysis, offers a powerful approach for reservoir and aquifer characterization
when integrated with other data types and methodologies (see Ekdale et al.,
2012 ). Most petroleum-industry-related studies have used ichnology to assist
in definition of depositional environments and reservoir quality and have their
focus on siliciclastic reservoir characterization ( Bann and Fielding, 2004;
Bockelie, 1991; Gerard and Bromley, 2008; Gingras et al., 1999, 2007, 2012;
Knaust, 2009a; McIlroy, 2004; Spila et al., 2007; Tonkin et al., 2010 ). Ichnology
has been used less as part of carbonate reservoir characterization, but its
applications are becoming more prevalent in the scientific literature ( Gingras
et al., 2002, 2007; Knaust, 2009b; Pemberton and Gingras, 2005 ).
In the rocks of carbonate aquifers, zones with macroporous and highly
permeable ichnofabrics have largely been overlooked by the hydrogeological
community due to the lack of recognition of trace fossils and unawareness that
high levels of bioturbation can influence groundwater flow. However, examples
of burrow-associated macroporosity in carbonate aquifers have been reported
by others in (1) the Cretaceous carbonate rocks of the Edwards-Trinity aquifer
system in Texas ( Fig. 1 ; Abbott, 1975; Barker and Ardis, 1996; Hovorka et al.,
1996, 1998; Maclay and Small, 1986; Rose, 1972; Small et al., 1996 ), (2)
the Cenozoic limestone of the Great Bahama Bank ( Beach, 1995 ), and (3)
the Pleistocene limestone of the Biscayne aquifer in southeastern Florida
( Cunningham and Sukop, 2011; Cunningham et al., 2006a,b, 2009, 2010;
Evans, 1984 ). Still, with the exception of Cunningham et al. (2009, 2010)
and Cunningham and Sukop (2011) , we have not identified any publications
specifically focused on the link between carbonate ichnology and groundwater