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Fig. 3. The main morphological elements of the Ombrone River delta plain.

Figure 3 The main morphological elements of the Ombrone River delta plain.

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Fig. 1. Location of study area and distribution of main lithological types of the Ombrone River basin. Most recent literature emphasizes that the evolu- tion of large Mediterranean deltas has been driven in particular by the rates of postglacial sea-level rise and In this paper, the results of a morphological and sedimentological study on the emerged delta of the Ombrone River are illustrated. This delta, even though
Fig. 1. Location of study area and distribution of main lithological types of the Ombrone River basin. Most recent literature emphasizes that the evolu- tion of large Mediterranean deltas has been driven in particular by the rates of postglacial sea-level rise and In this paper, the results of a morphological and sedimentological study on the emerged delta of the Ombrone River are illustrated. This delta, even though
Summary data for River Ombrone catchment
Summary data for River Ombrone catchment
Fig. 2. Sedimentological and stratigraphic features of the Ombrone River delta body. (a) Planimetric distribution of four fluvio-deltaic bodies built by the Ombrone River into the incised valley during the postglacial sea level rise. (b) Schematic W-—E cross section showing the retrogradational setting of the fluvio-deltaic bodies according to landward migration of the barrier-lagoon system. (c) Schematic cross section normal to the axis of the Ombrone River paleovalley.
Fig. 2. Sedimentological and stratigraphic features of the Ombrone River delta body. (a) Planimetric distribution of four fluvio-deltaic bodies built by the Ombrone River into the incised valley during the postglacial sea level rise. (b) Schematic W-—E cross section showing the retrogradational setting of the fluvio-deltaic bodies according to landward migration of the barrier-lagoon system. (c) Schematic cross section normal to the axis of the Ombrone River paleovalley.
Fig. 5. Location of surface samples. The monograms correspond to the lithological type according to the triangular classification by Tortora (1999). The double circle indicates cases of samples collected also on the beach ridge crest.
Fig. 5. Location of surface samples. The monograms correspond to the lithological type according to the triangular classification by Tortora (1999). The double circle indicates cases of samples collected also on the beach ridge crest.
Fig. 6. (a) Histograms of characteristic grain size distribution of the seven groups as defined basing on the dendrogram drawn with the Clustan Graphycs 5 program. (b) Areal distribution of the seven grain-size groups defined by cluster analysis. For grain-size distribution of each group, see (a). The Greek letter placed near samples with double circle specifies the grain-size typology of the sediment belonging to the crest of the beach ridge (see Fig. 7); the figure specifies the height at which the crest sample has been collected.
Fig. 6. (a) Histograms of characteristic grain size distribution of the seven groups as defined basing on the dendrogram drawn with the Clustan Graphycs 5 program. (b) Areal distribution of the seven grain-size groups defined by cluster analysis. For grain-size distribution of each group, see (a). The Greek letter placed near samples with double circle specifies the grain-size typology of the sediment belonging to the crest of the beach ridge (see Fig. 7); the figure specifies the height at which the crest sample has been collected.
Fig. 7. Histograms of characteristic grain-size distributions of the two sandy sediment typologies found on the crest of beach ridges with height not lower than 3 m. successions of Paleozoic to Paleogene age, the over- lying foredeep turbidites (““Macigno’’), the ophiolitic Liguride units, the deep-water limestone-shale Sub- Liguride units and the Quaternary trachyandesites of the Tuscan Magmatic Province (Monte Amiata; e.g., Abbate et al., 1994; Pandeli et al., 1994). Such a variety of source rocks is reflected in detrital modes of river and deltaic sand, which are relatively quartz- poor and contain feldspars and abundant carbonate, pelitic and metapelitic lithic grains, with significant serpentine. Composition of trunk-river sand upstream of the delta (Q32 F12 Lv2 Le 21 Lpl4 LchO Lm14 Lu4) is quite close to the average sand from the whole Tuscan Apennines (Tuscan Superprovince of Garzanti et al., 2002). 1 4 4144 1 . 1:
Fig. 7. Histograms of characteristic grain-size distributions of the two sandy sediment typologies found on the crest of beach ridges with height not lower than 3 m. successions of Paleozoic to Paleogene age, the over- lying foredeep turbidites (““Macigno’’), the ophiolitic Liguride units, the deep-water limestone-shale Sub- Liguride units and the Quaternary trachyandesites of the Tuscan Magmatic Province (Monte Amiata; e.g., Abbate et al., 1994; Pandeli et al., 1994). Such a variety of source rocks is reflected in detrital modes of river and deltaic sand, which are relatively quartz- poor and contain feldspars and abundant carbonate, pelitic and metapelitic lithic grains, with significant serpentine. Composition of trunk-river sand upstream of the delta (Q32 F12 Lv2 Le 21 Lpl4 LchO Lm14 Lu4) is quite close to the average sand from the whole Tuscan Apennines (Tuscan Superprovince of Garzanti et al., 2002). 1 4 4144 1 . 1:
Fig. 8. Paleogeographic scenarios of the Grosseto Plain over the Holocene.
Fig. 8. Paleogeographic scenarios of the Grosseto Plain over the Holocene.
Fig. 9. Beach ridge volumes of the northern and southern wings of the Ombrone River. The black line evidences the part of sediment due to wind action. Volumes have been calculated for some periods starting from Etruscan times.
Fig. 9. Beach ridge volumes of the northern and southern wings of the Ombrone River. The black line evidences the part of sediment due to wind action. Volumes have been calculated for some periods starting from Etruscan times.
Related topics:
GeologyGeomorphologyFluvial SedimentologyLittle Ice AgeHolocene Evolution of Deltas
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