Il Quaternario nella zona di Monterotondo (Roma)

Abstract

The Rome area has been thoroughly investigated since the last century for its wealth of interesting occurrences for Quaternary geology. However, there are aspects which require more in-depth research. This paper proposes new assessment tools relying on the combined use of litho- and morphostratigraphic units (remnant surfaces and landscapes in addition to buried erosional surfaces). This process is applied to the Monterotondo area (NE of Rome), where few studies have to date been carried out. New data has led to the reconstruction of a refined morpho-Iithostratigraphic sequence. This sequence has the typical setting of the terraced sequences generally found in more or less continuously uplifted areas, allowing for a reconstruction of the geological and paleo-geographical evolution of the area. The most interesting datum was the evaluation of base-level stability and intense erosion periods. The sequence spans the entire Quaternary and allows large-scale correlations and comparisons with stratigraphy of the Rome area. The paper indicates aspects of the sequence which, in some cases, do not fully match previous stratigraphic conclusions. The most significant are: (i) the outline of an erosional phase dating to the Lower Pleistocene; (ii) the identification of a broad remnant landscape in the area of Monterotondo - the development of this landscape has to be connected with a remarkably long period of base-level stability between the "Tufo rosso a scorie nere" (~430 Ka) and the "Tufo lionato" time (~360 Ka); (iii) the identification of 4 erosion/deposition cycles within the volcanic products referred to as the "Complesso dei tufi stratificati varicolori di La Storta" (La Storta Complex of stratified varicoloured tuffs), previously identified as only one formation in literature; (iv) the post-dating of the top of this formation.