Sediment recycling and adjustment of deposition during deglacial drowning of a low-accumulation shelf (NW Iberia)

摘要: Abstract Based on a well-established stratigraphic framework and 47 AMS-14C dated sediment cores, the distribution of facies types NW Iberian margin is analysed in response to last deglacial sea-level rise, thus providing case study sedimentary evolution high-energy, low-accumulation shelf system. Altogether, four main are defined. (1) A gravel-dominated occurs mostly as time-transgressive ravinement beds, which initially developed shoreface storm deposits shallow waters outer during lowstand; (2) widespread, mixed siliceous/biogenic-carbonaceous sand indicates areas moderate hydrodynamic regimes, high contribution reworked material, fluvial supply shelf; (3) glaucony-containing stationary position formed last-glacial rise by reworking older well authigenic mineral formation; (4) mud restricted confined Holocene fine-grained depocentres, located mid-shelf position. The observed spatial temporal these was essentially controlled local interplay supply, morphology, strength These patterns contrast high-accumulation systems where extensive dominant factor distribution. This emphasises importance large-scale erosion material recycling buildup drowning shelf. presence homogenous up 15-m thick transgressive cover above lag horizon contradicts common assumption sparse laterally accumulation high-energy rise. In this cover, very maximal 4-m thin depocentres highstand. formation related combination of: frequently occurring conditions; low overall terrigenous input adjacent rivers; large distance Galicia Mud Belt its supplier.