Fault-sourced alluvial fans and their interaction with axial fluvial drainage: An example from the Plio-Pleistocene Upper Valdarno Basin (Tuscany, Italy)

Fidolini, Francesco; Ghinassi, Massimiliano; Aldinucci, Mauro; Billi, Paolo; Boaga, Jacopo; Deiana, Rita; Brivio, Lara

doi:10.1016/j.sedgeo.2013.02.004

Cited by 38 publications

(46 citation statements)

References 51 publications

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“…2) During the late Pleistocene, the Arno river has undergone a drastic deviation, turning from a roughly southward path to the present one [91] [92] [96] [97]. This event could be an effect of the dextral displacement and uplift that the Rapolano ridge (Figure 7) has undergone to accommodate the supposed longitudinal shortening.…”

Section: ) In Several Sectors Of This Zone Significant Uplift Has Amentioning

confidence: 99%

Belt-Parallel Shortening in the Northern Apennines and Seismotectonic Implications

Viti¹,

Mantovani²,

Babbucci³

et al. 2015

IJG

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Major seismic activity in the Northern Apennines concentrates in few zones, distributed in a peculiar way. It is argued that such context may be plausibly explained as an effect of belt-parallel shortening, which has caused oroclinal bending of the longitudinal ridges formed during the Late Miocene to Lower Pliocene evolutionary phase. The main effects of this process, developed since the upper Pliocene, have mainly affected the outer sectors of the belt. The major seismic sources have generated in the zones where different oroclinal bendings of adjacent ridges have produced extensional/transtensional deformation. In the inner side of the Northern Apennines, belt parallel shortening has occurred at a lower rate. The main effects have resulted from the shortening of the Albano-Chianti-Rapolano-Cetona ridge. In particular, the proposed tectonic setting may account for the moderate seismic activity that occurs in the Firenze, Elsa, Pesa, Siena and Radicofani basins.

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Section: ) In Several Sectors Of This Zone Significant Uplift Has Amentioning

confidence: 99%

Belt-Parallel Shortening in the Northern Apennines and Seismotectonic Implications

Viti¹,

Mantovani²,

Babbucci³

et al. 2015

IJG

View full text Add to dashboard Cite

show abstract

“…This lower succession is capped by basin-axial alluvial sand and mud and by basin-marginal alluvial fan gravel and sand (Fidolini et al 2013a, b). Similarly, the Early -Middle Pleistocene Torrente Ciuffenna Synthem (UFF in Figs 1b & 2a) is composed of basin-axial fluvial gravel and sand and basin-marginal alluvial fan gravel (Fidolini et al 2013a). The Torrente Ciuffenna Synthem is ubiquitously topped by pedogenized alluvial mud.…”

Section: Geological Settingmentioning

confidence: 95%

“…Massive cobble-sized deposits, forming 1-1.5 m thick beds (Fig. 5a), are rarely found in inter-fan, piedmont areas to the north of the Castelfranco Fan (Fidolini et al 2013a;Ghinassi et al 2013). These deposits are commonly clast-supported with an abundant interstitial silty sand matrix and locally show a coarse-tail inverse grading.…”

Section: Proximal Facies Beltmentioning

confidence: 99%

“…3). Their stratigraphy has been outlined by Fidolini et al (2013a) and is articulated in three main intervals: (1) a lower aggradational interval, which records a balance between fault-generated subsidence and sediment supply; (2) a middle coarsening-upwards interval, which records an increase in sediment supply associated with a decreased subsidence rate; and (3) an upper fining-upwards interval, which records a progressive morphological re-equilibration of the faulted bedrock margin during a stage of tectonic quiescence. The sand-rich progradational interval is the main focus of the present study (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

“…Intense bioturbation indicates the colonization of proximal fans by vegetation between major floods, while their locally preserved sedimentary structures record tractional conditions. Massive beds in inter-fan areas could point to debris flow deposits (Fidolini et al 2013a;Ghinassi et al 2013), which were sourced from minor ravines draining the inter-fan areas.…”

Section: Proximal Facies Beltmentioning

confidence: 99%

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Morphodynamics and facies architecture of streamflow-dominated, sand-rich alluvial fans, Pleistocene Upper Valdarno Basin, Italy

Ghinassi

Ielpi

2016

Self Cite

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The overwhelming documentation of coarse-grained alluvial fans dominated by mass flow contrasts with the scarce accounts of finer grained, traction-dominated alluvial fans. To fill this gap, we present sedimentological and architectural data from a set of sand-rich, streamflow-dominated Pleistocene fans flanking the eastern Upper Valdarno Basin, Italy. The routing of sand-rich sediment resulted from the fast, intense weathering of the feldspar-rich, carbonatedeprived sandstone bedrock underlying the fan catchments. Although capable of entraining large boulders, high water discharge sustained tractional reworking along the proximal facies belts, hindering mass flow. The medial facies belts have a channelized, braided planform and are dominated by processes hardly distinguishable from those characterizing fluvial environments. Along the distal facies belts, extensive overbank tracts are composed of terminal splays and crevasse lobes, the spatial arrangement of which controlled the evolution of through-going tributary channels connected to the axial basin drainage. This study focused on the sedimentary processes, stratal architecture and morphodynamics of the alluvial fans and considered the effect of bedrock inheritance on their development. The results underline how granulometry and mass flow dominance are not distinctive of alluvial fan sedimentation per se and indicate how the critical detection of piedmont, radial palaeomorphology is crucial in the identification of ancient alluvial fans.

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Where will widening occur in an outwash braidplain? A new approach to detecting controls on fluvial lateral erosion in a glacierized catchment (north‐western Spitsbergen, Svalbard)

Weckwerth

Sobota

Greń

2021

Earth Surf Processes Landf

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The dynamics of fluvial system evolution depend on fluvial processes and their driving forces associated with climatic variations, which affect changes in the morphology of river channels and floodplains. Neither channel slope and morphology, nor the properties of fluvial sediment have previously been considered as determinants of active braidplain widening on outwash plains (formed from valley/alpine glaciers and confined by pre-existing topography) in the High Arctic region and in the forefields of retreating glaciers. Factors determining widening of braidplain activity of the Waldemar River outwash (north-western Spitsbergen, Svalbard) were analysed on the basis of geomorphological, sedimentological, glaciological and meteorological research, and indicate significant multiple correlations between meltwater discharge, precipitation, braidplain width, morphology of the braided channel and the textural features of braidplain deposits. The capability of multivariate adaptive regression splines to detect these relationships was described, and threshold values were identified. The results indicate that the rate of active braidplain widening is proportional to the meltwater outflow in proglacial rivers, which can decrease despite a growing rate of glacial ablation. A proposed model enables us to predict zones of braidplain prone to widening activity in the High Arctic (humid) outwash fans and plains as well as fans developed in arid intermountain basins. The necessary conditions to activate braidplain widening processes were (1) spatial changes in the outwash feeding system due to glacier terminus retreat and (2) crossing the thresholds in passive factors (S and d 50 ) controlling lateral erosion intensity. As a result, the braidplain reached a new dynamic equilibrium, in which high-magnitude-low-frequency extreme meltwater discharges were of particular importance in terms of braidplain dynamics and are the dominant controls on the pattern of distributary channels.

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Fault-sourced alluvial fans and their interaction with axial fluvial drainage: An example from the Plio-Pleistocene Upper Valdarno Basin (Tuscany, Italy)

Cited by 38 publications

References 51 publications

Belt-Parallel Shortening in the Northern Apennines and Seismotectonic Implications

Belt-Parallel Shortening in the Northern Apennines and Seismotectonic Implications

Morphodynamics and facies architecture of streamflow-dominated, sand-rich alluvial fans, Pleistocene Upper Valdarno Basin, Italy

Where will widening occur in an outwash braidplain? A new approach to detecting controls on fluvial lateral erosion in a glacierized catchment (north‐western Spitsbergen, Svalbard)

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