Geological map of Pliocene-Pleistocene deposits of the Ambra and Ombrone valleys (Northern Siena Basin, Tuscany, Italy)

Abstract

The study area is located across the Chianti Ridge (Tuscany, Italy), between the Upper Valdarno Basin and the Siena Basin. This area covers about 25 km 2 , forming a narrow belt oriented N -S and drained by the Ambra and Ombrone creeks, which flow northward and southward, respectively. Field mapping was carried out at 1:10,000 scale through an allostratigraphic-sedimentological approach. The study area deposits represent the infill of a SW-draining paleovalley, cut both in pre-Neogene bedrock and marine Pliocene deposits of the Siena Basin. The valley-fill succession consists of two main allounits (V1 and V2), which are conformably stacked in the northern sector of the study area, and unconformably offset in the southern sector. V1 comprises gravelly to sandy fluvial deposits, whereas V2 deposits show noticeable downvalley variability. V2 consists of poorly drained floodplain deposits in the northern sector of the paleovalley, whereas gravel and sand-bed river deposits fill its southern part. Alluvial-fan and palustrine deposits are also associated with V2 fluvial facies. A normal fault trending NW-SE is the main structural feature of the area. This fault cuts the V2 unit lowering the upstream reach and is thought to have promoted the marked facies changes observed in the fluvial deposits of unit V2.

Facies analysis of a Pliocene river‐dominated deltaic succession (Siena Basin, Italy): Implications for the formation and infilling of terminal distributary channels

“…The forced regression related to the aforementioned upper Piacenzian regional uplift led to the emersion of the basin and the subsequent evolution of a fluvial network. Remnants of ancient fluvial networks are represented by discontinuous outcrops of sandy‐gravelly Quaternary alluvial deposits that are located on the eastern basin margin and rest unconformably on Pliocene strata and pre‐Neogene bedrock (Magi, ; Aldinucci et al ., ; Bianchi et al ., ). Lastly, travertine was deposited discontinuously during the Quaternary, locally overlying both the pre‐Neogene bedrock and the Neogene deposits (Brogi et al ., ).…”

Tectonically driven deposition and landscape evolution within upland incised valleys: Ambra Valley fill, Pliocene–Pleistocene, Tuscany, Italy

“…The study succession accumulated both on Pliocene marine sediments and on pre‐Neogene bedrock (Aldinucci et al ., ), in response to the activity of normal faults (Baldi et al ., ; Bianchi et al ., ). The study area is located along the Chianti Ridge, and corresponds to a zone between the Upper Valdarno (Fidolini et al ., ; Ghinassi et al ., ) and Siena basins (Brogi, ; Martini et al ., ).…”

“…Micropalaeontological analyses ascribe the uppermost part of the marine succession to the latest Piacentian (Bambini et al ., ; Martini et al ., ; Arragoni et al ., ; Martini et al ., ), during which a regional tectonic doming caused a forced regression (Martini & Sagri, ). A 60 to 70 m thick fluvial valley‐fill succession overlies both the pre‐Neogene Units and the marine deposits of the Siena Basin (Aldinucci et al ., ; Bianchi et al ., ). The valley was fed from the north (Fig.…”

Geomorphological analysis of drainage changes in the NE Apennines piedmont area: the case of the middle Tavo River bend (Abruzzo, Central Italy)

“…In this process, field mapping was carried out at the 1:5,000 scale to investigate lithological features, superficial deposit cover, and the type and distribution of morphological field evidence of tectonics. Mapping was performed according to the guidelines of the Geological Survey of Italy and AIGeo (Italian Association of Physical Geography and Geomorphology) (ISPRA, 2007;ISPRA & AIGEO, 2018) and was also in accordance with the literature concerning morphotectonic mapping (Amato et al, 2018;Bianchi et al, 2013Bianchi et al, , 2015Calista et al, 2016;Chelli, Segadelli, Vescovi, & Tellini, 2016;Giano et al, 2014;Miccadei et al, 2019). Air-photo interpretation was performed using 1:33,000 scale stereoscopic air-photos (Flight GAI 1954and Flight Abruzzo Region 1981-1987Abruzzo Region, 1987;IGMI, 1954) and 1:5,000 scale orthophoto color images (Abruzzo Region, 2010) to support the geomorphological investigation.…”