Marine carbonate factories: Review and update

Abstract

AbstractThe carbonate factories model, as defined at the beginning of the century, provides a subdivision of marine carbonate sediment production‐systems based on the style of carbonate precipitation. The main factors controlling marine carbonate precipitation are light, water temperature, nutrients, salinity, substrate and carbonate saturation. Site‐specific controls influencing the systems comprise ocean currents, upwelling and non‐upwelling systems, ocean‐atmosphere systems, atmospheric systems, shallow‐water dynamics, and terrestrial sediment and water input.Each factory has its own sediment‐production window linking optimal sediment production with selected environmental controls. Sediment production in the tropical factory (T‐factory) is light and temperature‐dependent and negatively impacted by nutrients. Sediment production and export depends on the size of the shallow‐water areas within the photic zone. The cold‐water‐coral factory (CWC‐factory) is nutrient‐dependent, but light‐independent. Sediment production relates to nutrient supply enabling the growth of the cold‐water corals. The cool‐water factory (C‐factory) displays a strong link to nutrients and water temperature, with parts that are light‐dependent, for example, sediment production in kelp dominated environments. The sediment mineralogy and sediment production area within the high‐energy hydrodynamic zone govern sediment distribution with sediment behaviour comparable to siliciclastics. The microbial/mud‐mound factory (M‐factory) is nutrient‐dependent and to some extent temperature and light‐independent. Sediment production and export is referred to here as slope shedding and links to the main sediment production on the upper slope. The planktic factory (P‐factory) depends on variations in light, temperature and nutrients resulting in fluctuating pelagic fall‐out.Platform morphologies and slope profiles are also factory specific: T‐factories show a rimmed flat‐topped platform with adjacent exponential slopes or a carbonate ramp morphology; CWC‐factories display mound morphologies with steep slopes; C‐factories are associated with open shelf systems and Gaussian shaped slope profiles; while M‐factories are characterized by individual steep‐sided mounds or flat‐topped platforms with deepened margins and a linear shaped slope profile. The P‐factory provides biotic grains to all environments and at times, like for the Cretaceous, may dominate sedimentation patterns in the basin realm.The sequence stratigraphic patterns substantially differ between factories. The T‐factory being light‐dependent is characterized by higher sediment production when the platform tops are flooded (highstand shedding). It displays decoupled sediment wedges with the partial infill of accommodation in the shallow‐water realm and major sediment export towards the slopes and surrounding basins. The CWC‐factory is marked by in situ production and deposition with limited sediment export forming single CWC spots or sediment accumulation ridges. The C‐factory has a siliciclastic equivalent style of sediment distribution with lowstand‐dominated, shelf edge wedges and a shaved‐off shelf during sea‐level highstands. Slope shedding marks the M‐factory in which sediment production occurs within the upper slope realm of the flat‐topped platforms both during highstands and lowstands in sea‐level. This allows for fairly continuous sediment production exhibiting minor impact of sea‐level changes, but with progradation, aggradation and retrogradation of the system being only limited by local environmental changes. P‐factory sediment production may vary in accordance with variations in sea‐level, providing time‐lines and systems tracts boundaries in the pelagic realm.In summary, each factory is branded by an individual set of features, for example, production window, sediment production and export, morphologies and slopes. It is this unique set of variables marking each factory that determines the factory‐dependent response to small‐scale and large‐scale environmental changes through space and time as shown in the sequence stratigraphic development.