Siliclastic sedimentation within a region of shallow carbonate production is dictated by the character of the onshore sediments. This is coupled with relative or absolute changes in sea level, storm deposits and fuvial activity. Together these control the magnitude, extent, and character of allochthonous siliclastic transport and deposition.
- The energy of the environment characterizes sediment grain size. Typically coarser sediments are found where hydraulic regimes are intense and finer sediments are allowed to settle out of suspension in quieter waters. Storm deposits and regions where wave energy is high exemplify the former, while lagoons (landward of rimmed platforms) and tidal flats may prescribe the latter.
- A drop in sea level or regional tectonic uplift may result in a progradation of terrigenous sediment seaward. This newly introduced sediment may blanket exposed carbonates and influence topography by controlling local weathering (See Antecedent Topography: Karstification). A drop in sea level (or tectonic uplift) will also change the local hydraulic regime along the profile of the platform as deeper, quieter water locations become shallower and subsequently subjected to higher energies and coarser siliclastic sediment accumulations.
- Suspended sediment may shallow the depth of the photic zone, which in turn can deter the growth of benthic carbonate-producing organisms.
Index to carbonate shelf sediments