As with the accomodation of siliciclastics described in the section on Physical Accomodation, the accommodation space for carbonates, is affected by hydrodynamics, but also the capacity of organisms to produce and to accumulate sediments above certain hydrodynamic thresholds. This later effect is the ecological accommodation defined by Pomar (2001 a and b).
This Figure is of cross sections of the Upper Miocene rocks of two islands of the Balearic archipelago (Mallorca and Menorca) and provides a contrast between physical and ecological accommodation.
The lower portion of the section is of the Early Tortonina which maintained a ramp dominated by an extensive rhodalgal lithofacies and no coral reefs. This organic community has no abilty to build the sediment surface up to sea level and its accommodation was seen as that of "Physical Accommodation".
In contrast in the upper portion is of the Upper Miocene Late Tortonian-Early Messinian. This exhibits well-developed progradational reefal platforms, including the Llucmajor Platform reef complex. It builds to sea level in response to changes in the local ecology that have enabled the organic community to build to sea level. Thus the accommodation of this upper carbonate platform is that of an ecologically controlled setting.
Carbonate systems, and in particular platfrom exhibit a diversity that is a consequence of a wide variety of carbonate production processes and mechanisms that cause their redistribution within the basin. Each different biotic system has a unique competence (ecological accommodation) for building above and below the hydrodynamic shelf equilibrium profile of Swift and Thorne (1991). Thus production depends on biological evolution including ecological requirements (substrate, competitive displacement, etc); the type, size and efficiency of the carbonate factory, which in turn, depends on the area available to thriving carbonate producing biota (basin floor physiography), on intrabasinal conditions (nutrients, temperature, water energy, water transparency, salinity, oxygen, Ca2+ and CO2 concentrations, Mg/Ca ratio, alkalinity, etc). Furthermore, sediment dispersal depends on the interaction between the physical characteristics of the different types of sediment being produced (grain size, bulk density as determined by porosity within the grain e.g. intraskeletal porosity, etc) and the hydraulic energy ambient to the production loci, and its modification by binding, trapping, baffling and framework building (Ginsburg and Lowenstam, 1958) as well as by early cementation processes.
So, ecological accommodation matches the accomodation of Jervey (1998) as the "the space available for potential sediment accumulation" but with some less than subtle considerations. This ecological accommodation represetns the "potential" space available for carbonate sediment to fill and is the combined product of rates of carbonate sediment accumulation as modulated by the ecological requirements of the carbonate producing organisms, movement of the sea surface (eustasy: global sea level measured from a datum such as the center of earth) and movement of the sea floor (tectonics).
References
Ginsburg, RN, and Lowenstam, HA, 1958, The influence of marine bottom communities on the depositional environments of sediments: Journal of Geology, v. 66, p. 310-318.
Jervey, M.T., 1988, Quantitative geological modeling of siliciclastic rock sequences and their seismic expression, in Wilgus, C.K., Hasting, B.S., Kendall, C.G.St.C, Posamentier, HW, Ross, CA, and Van Wagoner, JC, eds., Sea-level changes: an integrated approach: Tulsa, OK, Society of Economic
Paleontologists and Mineralogists, Special Publication No. 42, p. 47-69.
Posamentier, Henry W., and George P. Allen, 1999, "Siliciclastic Sequence Stratigraphy - Concepts and Applications", published by the Society of Economic Petrologists and Paleontologists, 216 pages.
Pomar, L., 2001 (a), Ecological control of sedimentary accommodation: evolution from a carbonate ramp to rimmed shelf, Upper Miocene, Balearic Islands: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 175, p. 249-272.
Pomar, L., 2001 (b), Types of carbonate platforms, a genetic approach: Basin Research, v. 13, p. 313-334.
Swift, D.J.P., and Thorne, J.A., 1991, Sedimentation on continental margins, I: a general model for shelf sedimentation, in Swift, D.J.P., Oertel, G..F, Tillman,
R.W., and Thorne, J.A., eds., Shelf sand and sandstone bodies, International Association of Sedimentologists Special Publication, No. 14, p. 3-31.
