Middle to Late Pleistocene palaeoenvironmental evolution of the southeastern Alpine Valeriano Creek succession (northeastern Italy)

Abstract

The Middle-Late Pleistocene alluvial and lacustrine succession of Valeriano Creek (southeastern Alpine foothills, 190 m a.s.l.) documents the environmental evolution of the piedmont plain before the onset of the Last Glacial Maximum (LGM). The sedimentary record was investigated by multidisciplinary stratigraphical and sedimentological studies coupled with petrographic and palaeobotanical analysis. A chronology has been provided by luminescence, radiocarbon dating and pollen biochronology. The succession developed at the valley mouth of a small catchment and is confined in the piedmont plain by the alluvial fans of major rivers. The oldest deposits were formed during a cold phase during the late Middle Pleistocene. This part of the piedmont plain was generally stable until Termination II, when it was trenched more than 15 m deep by watercourses. The infilling succession of the trench, mostly by low-energy alluvial sediments interbedded with mire and peat deposits, documents, for the first time on the southern side of the Alps, the relationships between fluvial activity, vegetation and climate change at the foothills piedmont plain during late Marine Isotope Stage (MIS) 5. The stadial-interstadial climate forcing implies a local reorganisation of fluvial dynamics and of forest composition, although substantial plant cover persisted even during cooler stadials. In accordance with coeval alluvial and speleothem records from the northern side of the Alps, this environmental evolution supports a very restricted Alpine glaciation of the main fluvial catchments of the southeastern Alps during MIS 5a-d.

Correlating Alpine glaciation with Adriatic sea‐level changes through lake and alluvial stratigraphy

“…In the northern Adriatic, it has been found in several long successions (Amorosi et al , 1999; Tosi et al , 2007) and is also supported by palynological evidence in the lower Friulian plain (Pini et al , 2009; Fig. 1) and at the Friulian foothills of the Alps (Monegato et al , 2010a).…”

“…The onset of the Middle Würm (= MIS 4) did not bear important sedimentary changes either in the outer plains or the Fimon Basin. Alluvial successions in the Venetian–Friulian Plain do not record an increase in sediment supply from the Alpine valleys (Monegato et al , 2010a), a circumstance which does not support the hypothesis of a glacier expansion in the piedmont of the Alps, suggested by some authors (van Husen, 2004). In contrast to the Western and Central European landscape, missing forest during most of the Middle Weichselian, south of the Alps a major forest withdrawal occurred late in the Middle Würm, at about 38.2 ± 1.45 cal.…”

“…140 ka) had a severe impact on the landscape of the eastern Southern Alps and the piedmont plain (Pini et al , 2009). Large valley glaciers reached the valley outlets (Monegato et al , 2010a) and the aggradation of the outwash rivers exceeded 25 m in the lower plain (Fig. 10b).…”

“…At this time, a significant change is also recorded by sedimentary patterns. Southern Alpine alluvial systems became more dynamic and alluvial fans prograded onto the piedmont plain (Monegato et al , 2010a). At Lake Fimon, the first episode of sediment supply by an external tributary is recorded.…”

Combining allostratigraphic and lithostratigraphic perspectives to compile subregional records of fluvial responsiveness: The case of the sustainably entrenching Palancia River watershed (Mediterranean coast, NE Spain)

“…At the same time, an allostratigraphic unit represents fluvial response at the geographical scale over which it can be traced. Therefore, aggregating allostratigraphic information (e.g., from the allomember to the alloformation or allogroup level) inherently scales up stratigraphic subunits and consistent periods of fluvial sediment-landform evolution from local to regional (or even larger) scales (Autin, 1992(Autin, , 1996Ely et al, 1993;Straffin, 2001;Monegato et al, 2010). Because the fluvial record of Pleistocene and Holocene sedimentation is geographically discontinuous along the Palancia River valley, morpholithostratigraphic information (relative position of lower unconformities, lithology, texture, etc.)…”