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dc.contributor.authorMaselli, Vittorio
dc.contributor.authorNormandeau, Alexandre
dc.contributor.authorNones, Michael
dc.contributor.authorTesi, Tommaso
dc.contributor.authorLangone, Leonardo
dc.contributor.authorTrincardi, Fabio
dc.contributor.authorBohacs, Kevin M.
dc.date.accessioned2020-04-21T09:46:56Z
dc.date.available2020-04-21T09:46:56Z
dc.date.issued2020
dc.identifier.citationGeologyen_US
dc.identifier.other10.1130/G47451.1
dc.identifier.urihttps://dspace.igf.edu.pl/xmlui/handle/123456789/32
dc.description.abstractQuantification of the interaction between river discharge and tides is vital to characterize fluvio-deltaic systems, to identify diagnostic elements of tidal signatures in the rock record, and to reconstruct paleogeographies. In modern systems, even microtides can significantly influence delta morphodynamics; yet, many fundamental processes, particularly in prodeltaic settings, remain elusive. Here, by combining a unique process-product data set acquired during a flood event of the Po River (Italy) with numerical modeling, we show that tidal signatures are recorded in the open-water prodelta zone of a microtidal system. Based on the analyses of box-cores collected before and after a flood off the main distributary channel, we interpreted storm beds, tide-modulated flood strata of alternating normal and inverse graded beds, and rapid bioturbation. Modeling of the river discharge indicates that, at the peak of the flood, the steepening of the water-surface profile forced by 0.15 m lowering of sea level during low tides generated an 8% increase in river flow velocity. The alternation of profile steepness and associated cyclicity in flow strength during consecutive tidal cycles controlled the sediment load of the plume and, consequently, led to the deposition of tidal-modulated strata. Formation of microtidal signals appears to be enhanced in fluvio-deltaic successions characterized by multiple distributaries and in basins where river floods are out of phase with storm-wave activity. Bioturbation of sediment, which can start during the waning stage of the flow, and erosion by storm waves hamper the preservation of tidal signals, unless rapid burial occurs. The recognition of tidal-modulated strata in river-dominated settings may facilitate the characterization of mudstone reservoirs and reconstruction of paleogeographic conditions during deposition.en_US
dc.language.isoen_USen_US
dc.publisherThe Geological Society of Americaen_US
dc.relation.ispartofseriesGold Open Access
dc.titleTidal modulation of river-flood deposits: How low can you go?en_US
dc.typeArticleen_US


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