Shoal‐water deltas in high‐accommodation settings: Insights from the lacustrine Valimi Formation (Gulf of Corinth, Greece)

Abstract

The stratigraphic architecture of shoal-water deltaic systems developed in low-accommodation settings is relatively well-known. In contrast, the features of shoal-water deltas developed in high-accommodation settings remain relatively poorly documented, especially when compared with the available data sets for Gilbert-type deltaic systems developed in the same settings. The lacustrine Valimi Formation (Gulf of Corinth, Greece) provides an opportunity to investigate the facies assemblage and architectural style of shoal-water deltaic systems developed in high-accommodation settings. The studied interval accumulated during the Pliocene and Pleistocene and represents part of the early syn-rift Gulf of Corinth succession. Six facies associations, each described in terms of depositional processes and geometries, have been identified and interpreted to represent a range of proximal to distal deltaic sub-environments: delta plain, distributary channel, mouth-bar, delta front, prodelta and open lake. The facies associations and their architectural elements reveal characteristics which are not common in traditionally described shoal-water deltas. Of note, different facies arrangements are observed in the distributary channels in different sectors of the delta, passing from thick single-storey channel fills embedded within delta-plain fines in landward positions, to thin, amalgamated and multi-storey channels closer to the river mouth. This study proposes a new depositional model for shoal-water deltas in high-accommodation settings documenting, for the first time, that shoal-water delta deposits can form a substantial part of stratigraphic successions that accumulate in these settings. The proposed depositional model provides new criteria for the recognition and interpretation of these deposits; the results of this study have applied significance for reservoir characterization.

Interaction of an antecedent fluvial system with early normal fault growth: Implications for syn‐rift stratigraphy, western Corinth rift (Greece)

“…Facies analysis of the Valimi Formation is also presented in Ambrosetti et al . () and is interpreted as the expression of the shoal‐water deltas.…”

“…It consists of around 12 CU successions (20 to 50 m thick) of lacustrine deposits overlain by small pebble to sand grade deltas (up to 15 m thick) that prograded eastward into a shallow lacustrine environment. Facies analysis of the Valimi Formation is also presented in Ambrosetti et al (2016) and is interpreted as the expression of the shoal-water deltas.…”

Source-to-sink analysis of continental rift sedimentation: Triassic Cuyo basin, Precordillera Argentina

“…Accommodation has been defined as: "the space made available for potential sediment accumulation" (Jervey, 1988). Later work (Muto and Steelb, 2000) has proposed that available space can only be interpreted when appropriate thickness can be measured at a specified site and time in order to infer and discuss high-versus low-accommodation settings (Allen and Fielding, 2007;Ambrosetti et al, 2017). Our age constraints enable us to interpret sedimentation rates for the lower conglomeratic section higher than 25.1 m/Ma, since the basal age is from the basement, and approximately 20.3 m/Ma for the upper half of the Cerro Puntudo Formation.…”

Polyphase extensional basins: interplay between tectonics and sedimentation in the Neogene Siena-Radicofani Basin (Northern Apennines, Italy)

“…7B), which at places contain lens-shaped conglomerate bodies. These features suggest a deposition in a marine shoal-water delta environment, in which lens-shaped conglomerates can be interpreted as distributary channels (sensu Ambrosetti et al 2017).…”