Environmental Engineering Reference
In-Depth Information
Chapter 26
Mixed Siliciclastic/Carbonate
Systems
John-Paul Zonneveld, * ,1 Murray K. Gingras, * Tyler W. Beatty,
David J. Bottjer, James R. Chaplin, } Sarah E. Greene,
Rowan C. Martindale, Scott A. Mata, Luke P. McHugh, *
S. George Pemberton * and Jesse A. Schoengut *
*Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta,
Canada, Department of Geology and Geophysics, University of Calgary, Calgary, Alberta,
Canada, Department of Earth Sciences, University of Southern California, Los Angeles,
California, USA, } Oklahoma Geological Survey, University of Oklahoma, Norman, Oklahoma, USA
1
Corresponding author: e-mail: zonneveld@ualberta.ca
1. INTRODUCTION
Mixed siliciclastic/carbonate depositional systems are distinguished by the
pervasive and discrete co-occurrence of both siliciclastic and carbonate litho-
types. Ideally, the lithotypes should be interlaminated, interbedded, or inter-
stratified. Admixture of siliciclastic and carbonate sediment can occur due
to a variety of factors, most of which are centered on either spatial variability
in the facies distribution (i.e., lateral facies mixing) or temporal variability in
the sediment type (i.e., variation in sediment supply/stratigraphic occurrence)
( Brett et al., 2010; Budd and Harris, 1990; Lomondo and Harris, 1991;
McNeill et al., 2010; Mount, 1984 ). In most examples, trends of mixing vary
strongly along both depositional strike and dip as a function of proximity to
sources of carbonate or clastic sediment. In some cases, such as tropical
coastal areas with ephemeral fluvial input, the mixing varies strongly in both
the geographical sense (proximity to the clastic point source) and the temporal
sense (periodicity/seasonality of fluvial flow). In other examples, sediment
mixing may occur during rare, high-intensity events (such as storms) and
may be limited to discrete horizons within otherwise unmixed successions
( Mount, 1984 ). Finally, sediment mixing may be a function of cycles in the
rates of sedimentation, with intercalation of sediment-starved concentrations
and obrution deposits ( Brett et al., 2010 ).
Sea-level fluctuations have commonly been implicated in the development
of mixed systems. In some cases, such as the South Florida Neogene, changes in
 
 
 
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