Anatomy of A Shoreline Regression: Implications For the High-Resolution Stratigraphic Architecture of Deltas

Clinoforms and clinoform systems: Review and dynamic classification scheme for shorelines, subaqueous deltas, shelf edges and continental margins

“…1981; Patruno et al, 2015a;Ainsworth et al, 2017) in association with the progradation of either shorelines and subaerial deltas ("shoreline clinoforms"), or underwater sediment slopes of similar scale ("deltascale subaqueous clinoforms"). In particular, shoreline clinoforms are formed when transitioning from confined to unconfined water flow in neritic waters, either close to the river mouth (via delta front/shoreface migration) or alongshore (via redistribution and redeposition of the sediment load) (Fig.…”

“…While every bed-scale dipping surface in a delta-front or shoreface succession defines a clinoform, most individual delta-scale clinoforms that are visible in outcrops, detectable in cores and/or resolvable in seismic reflect stratigraphic discontinuities and/or variations in cementation or sandstone/shale content. These are driven by enhanced wave scour/erosion or sediment starvation/hiatus, which in turns reflect minor variations in river feeder discharge, relative sea-level, sediment supply and/or wave climate, with highly variable temporal scale significance (Hampson, 2000;Hampson and Storms, 2003;Roberts and Sydow, 2003;Gerber et al, 2008;Charvin et al, 2011;Zecchin and Catuneanu, 2013;Patruno et al, 2015bPatruno et al, , 2015cAinsworth et al, 2017). Regressive transits of delta-scale clinoforms generates the typical "parasequences" in marginal to shallow-marine successions (corresponding to a clinoform set), whereas repeated, high-frequency regressive-transgressive cross-shelf transits determines the stratigraphic architecture of shelves and shelf-edge clinothems (see later) (Van Wagoner et al, 1990;Burgess and Hovius, 1998;Johannessen and Steel, 2005;Olariu and Steel, 2009;HellandHansen et al, 2012).…”

“…8) reflect regional or local fluctuations in sediment supply and relative sea-level. Local fluctuations are typically caused by autogenic processes such as deltalobe shifting, differential compactional subsidence of shelfal muds in distal locations or sedimentary system self-organization linked to substrate physiography, such as autoretreat, autoincision and autoaccelleration (Clifton, 1981;Muto and Steel, 1992, 2004Helland-Hansen and Martinsen, 1996;Hampson and Storms, 2003;Muto et al, 2007;Charvin et al, 2010;Leva López et al, 2014;Patruno et al, 2015c;Ainsworth et al, 2017). Regional fluctuations are caused by allogenic processes, such as eustatic sea-level changes or tectonically-generated regional changes in relative sea-level or sediment supply rates (e.g., variations in advance and retreat of Italian glaciers at the same centennial/millennial scale with the sediment supply fluctuations in the Adriatic basin, as reported by Pellegrini et al, 2018).…”

“…While on the short term (< 10 years), storms are the main agents responsible for the changes in shoreline morphologies by rapid redistribution of nearshore sediment (Morton et al, 1995), during longer timescales the shoreline geomorphology and the stratigraphic architecture of shoreline clinoform successions are sensitive to even the most subtle and high-frequency fluctuations in relative sea-level, sediment supply, climate, basin hydrodynamics, sediment compaction and human influence (Morton and Suter, 1996;Foyle and Oertel, 1997;Morales, 1997;Sornoza et al, 1998;Hampson, 2000Hampson, , 2010Kuehl, 2000a, 2000b;Stive et al, 2002;Forbes et al, 2004;Mortimer et al, 2005;Bhattacharya, 2006;Charvin et al, 2011;Marriner et al, 2012;Ainsworth et al, 2017).…”

What is the topset of a shelf‐margin prism?

“…There is general agreement that there are two main categories of clinoform in margin architecture; delta‐scale clinoforms that build shelf stratigraphy and occur mainly in water depths from 10 m to 150–200 m, and very large (100 s of m to kms) deepwater (bathyal) clinoforms that occur mainly as margin‐building increments. The flat‐lying topsets of the large clinothems, when seen only on seismic data, are often little described internally compared to the deeper water correlative strata (but there are exceptions, see Ainsworth et al, ; Lobo & Ridente, ; Pellegrini et al, ; Rossi, Paterson, Helland‐Hansen, Claussen, & Eide, ). However, the complexity of facies and sub‐environments of topsets is well known from classical shallow‐marine and deltaic literature, for example, from the North Sea Brent Delta (Graue et al, ; Helland‐Hansen, ), Barents Sea deltas (Glørstad‐Clark, Birkeland, Nystuen, Faleide, & Midtkandal, ; Klausen et al, ), Western Interior Seaway (Mellere & Steel, ), or modern deltas (Olariu, ).…”