Lantzsch, Hendrik; Hanebuth, Till J J; Henrich, Rüdiger (2010): X-ray diffraction analysis, binocular component analysis and radiocarbon dating of sediment cores from the NW Iberian shelf system. PANGAEA, https://doi.org/10.1594/PANGAEA.743922, Supplement to: Lantzsch, H et al. (2010): Sediment recycling and adjustment of deposition during deglacial drowning of a low-accumulation shelf (NW Iberia). Continental Shelf Research, 30(15), 1665-1679, https://doi.org/10.1016/j.csr.2010.06.013
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Based on a well-established stratigraphic framework and 47 AMS-14C dated sediment cores, the distribution of facies types on the NW Iberian margin is analysed in response to the last deglacial sea-level rise, thus providing a case study on the sedimentary evolution of a high-energy, low-accumulation shelf system.
Altogether, four main types of sedimentary facies are defined. (1) A gravel-dominated facies occurs mostly as time-transgressive ravinement beds, which initially developed as shoreface and storm deposits in shallow waters on the outer shelf during the last sea-level lowstand; (2) A widespread, time-transgressive mixed siliceous/biogenic-carbonaceous sand facies indicates areas of moderate hydrodynamic regimes, high contribution of reworked shelf material, and fluvial supply to the shelf; (3) A glaucony-containing sand facies in a stationary position on the outer shelf formed mostly during the last-glacial sea-level rise by reworking of older deposits as well as authigenic mineral formation; and (4) A mud facies is mostly restricted to confined Holocene fine-grained depocentres, which are located in mid-shelf position.
The observed spatial and temporal distribution of these facies types on the high-energy, low-accumulation NW Iberian shelf was essentially controlled by the local interplay of sediment supply, shelf morphology, and strength of the hydrodynamic system. These patterns are in contrast to high-accumulation systems where extensive sediment supply is the dominant factor on the facies distribution.
This study emphasises the importance of large-scale erosion and material recycling on the sedimentary buildup during the deglacial drowning of the shelf. The presence of a homogenous and up to 15-m thick transgressive cover above a lag horizon contradicts the common assumption of sparse and laterally confined sediment accumulation on high-energy shelf systems during deglacial sea-level rise. In contrast to this extensive sand cover, laterally very confined and maximal 4-m thin mud depocentres developed during the Holocene sea-level highstand. This restricted formation of fine-grained depocentres was related to the combination of: (1) frequently occurring high-energy hydrodynamic conditions; (2) low overall terrigenous input by the adjacent rivers; and (3) the large distance of the Galicia Mud Belt to its main sediment supplier.
Median Latitude: 42.305566 * Median Longitude: -9.234311 * South-bound Latitude: 41.499667 * West-bound Longitude: -9.516667 * North-bound Latitude: 43.038333 * East-bound Longitude: -8.950000
Date/Time Start: 2006-08-20T06:31:00 * Date/Time End: 2008-06-16T11:33:00
GeoB11001-2 * Latitude: 42.249889 * Longitude: -9.083333 * Date/Time: 2006-08-20T06:31:00 * Elevation: -136.0 m * Campaign: POS342 * Basis: Poseidon * Method/Device: Giant box corer (GKG) * Comment: 34cm, 4xL, 4xSurface, pore water
GeoB11001-3 * Latitude: 42.250028 * Longitude: -9.083500 * Date/Time: 2006-08-20T08:10:00 * Elevation: -136.0 m * Recovery: 1.14 m * Campaign: POS342 * Basis: Poseidon * Method/Device: Vibro corer (VC)
Datasets listed in this publication series
- Lantzsch, H; Hanebuth, TJJ; Henrich, R (2010): (Table 2) Radiocarbon dates and age calibration. https://doi.org/10.1594/PANGAEA.743870
- Lantzsch, H; Hanebuth, TJJ; Henrich, R (2010): Binocular component analysis performed on the grain-size fraction 250–500 µm on 325 samples from the NW Iberian continental shelf. https://doi.org/10.1594/PANGAEA.743920
- Lantzsch, H; Hanebuth, TJJ; Henrich, R (2010): X-ray diffraction analysis of sediment samples from the NW Iberian shelf system. https://doi.org/10.1594/PANGAEA.743921