Depositional architecture, facies character and geochemical signature of the Tivoli travertines (pleistocene, acque albule basin, central Italy)
Articolo
Data di Pubblicazione:
2017
Citazione:
Depositional architecture, facies character and geochemical signature of the Tivoli travertines (pleistocene, acque albule basin, central Italy) / G. Della Porta, A. Croci, M. Marini, S. Kele. - In: RIVISTA ITALIANA DI PALEONTOLOGIA E STRATIGRAFIA. - ISSN 2039-4942. - 123:3(2017), pp. 487-540.
Abstract:
Facies character, diagenesis, geochemical signature, porosity, permeability, and geometry of the
upper Pleistocene Tivoli travertines were investigated integrating information from six borehole cores, drilled along
a 3 km N-S transect, and quarry faces, in order to propose a revised depositional model. Travertines overlie lacustrine
and alluvial plain marls, siltstones, sandstones and pyroclastic deposits from the Roman volcanic districts. In the
northern proximal area, with respect to the inferred hydrothermal vents, travertines accumulated in gently-dipping,
decametre-scale shallow pools of low-angle terraced slopes. The intermediate depositional zone, 2 km southward,
consisted of smooth and terraced slopes dipping S and E. In the southernmost distal zone, travertine marshes
dominated by coated vegetation and Charophytes interfingered with lacustrine siltstones and fluvial sandstones and
conglomerates. Travertine carbon and oxygen stable isotope data confirm the geothermal origin of the precipitating
spring water. The travertine succession is marked by numerous intraclastic/extraclastic wackestone to rudstone
beds indicative of non-deposition and erosion during subaerial exposure, due to temporary interruption of the
vent activity or deviation of the thermal water flow. These unconformities identify nine superimposed travertine
units characterized by aggradation in the proximal zone and southward progradation in the intermediate to distal
zones. The wedge geometry of the travertine system reflects the vertical and lateral superimposition of individual
fan-shaped units in response to changes in the vent location, shifting through time to lower elevations southward.
The complexity of the travertine architecture results from the intermittent activity of the vents, their locations, the
topographic gradient, thermal water flow paths and the rates and modes of carbonate precipitation.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
travertine; Pleistocene; Tivoli; facies; depositional architecture; stable isotope geochemistry
Elenco autori:
G. Della Porta, A. Croci, M. Marini, S. Kele
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