Quantitative sequence stratigraphy

Accommodation and sediment‐supply controls on clastic parasequences: A meta‐analysis

“…At parasequence scale, the rates of creation of accommodation resulting from subsidence and eustatic fluctuations control the thickness of parasequences by driving aggradation and causing burial of older deposits (Wehr, ; Emery & Myers, ; Ainsworth et al ., ; Fig. B).…”

“…Further investigation of controls on parasequence architectures is therefore warranted, and quantitative assessments undertaken on large datasets and with consideration of the origin and geological context of parasequences can improve understanding of the significance of controlling factors (cf. Ainsworth et al ., , ; Colombera & Mountney, ).…”

“…B). At a fundamental level, the water‐depth and gradient of the shelf or ramp into which a shoreline builds out determine the (decompacted) thickness of a parasequence and influence the rate and amount of shoreline progradation it records (Heward, ; Jervey, ; Emery & Myers, ; Reynolds, ; Ainsworth et al ., , ). The seabed bathymetry is itself a function of the rate at which accommodation is generated and of spatial variations thereof, and is also influenced by the rate of sediment supply and by type and energy of the process regime operating therein (Swift & Thorne, ).…”

“…Accordingly, the magnitude of A/S, by regulating the relative amount of nearshore aggradation and shoreline progradation, should be reflected in the regressive shoreline trajectory of a parasequence (Helland‐Hansen & Martinsen, ; Hampson, ; Løseth et al ., ; Helland‐Hansen & Hampson, ). It is also postulated that rates of sediment supply might control the fraction of sand or sandstone of a parasequence, and that, therefore, the ratio between parasequence thickness and sand fraction (T/SF ratio) should represent a proxy of A/S (Ainsworth et al ., , ). Moreover, the A/S ratio determines the preservation potential of normal‐regressive units (Cattaneo & Steel, ; Zecchin et al ., ), and is also thought to control the proportions and vertical trends of lithofacies and facies associations in parasequences, by affecting the relative degree of preservation of different facies belts (Swift et al ., ; Cant, ; Helland‐Hansen & Hampson, ).…”

“…Notwithstanding possible variations in sediment supply, this should result in predictable parasequence arrangements and stacking patterns, by determining stratigraphic variations in the amount of aggradation recorded in consecutive parasequences and in their regressive shoreline trajectories. So, for example, parasequence aggradation is expected to progressively increase through transgression and progressively decrease through highstand (Ainsworth et al ., ; Fig. E), whereas the regressive shoreline trajectories of successive parasequences are expected to portray a concave‐seaward trajectory in highstand systems tracts and a concave‐landward trajectory in lowstand systems tracts (Posamentier et al ., ; Posamentier & Allen, ; Catuneanu, 2019a; Fig.…”