Soil evolution and origin of landscape in a late Quaternary tectonically mobile setting: The Po Plain-Northern Apennines border in Lombardy (Italy)

Abstract

The interactions among Quaternary (paleo-) soil-forming, erosion, re-deposition and geomorphic processes at the origin of the present-day landscape are discussed at three isolated tectonic reliefs of the Southern Po Foredeep Basin of Lombardy (San Colombano, Casalpusterlengo and Zorlesco reliefs, Italy). These sites offer the possibility to combine different scales of geopedological, geomorphological, stratigraphic and structural observations, to unravel the contribution of climate and tectonics to the Quaternary geological evolution and to the origin of the landscape.Field surveys, laboratory analyses and soil micromorphology were used to characterize the Late Quaternary pedogenic processes acting on different (paleo)surfaces, in combination with the detailed study of seven selected soil profiles. Pedo-stratigraphic correlations revealed that two alluvial/loess-paleosol sequences, which originated from the Late Pleistocene to Holocene glacial/interglacial fluctuations, are differently preserved throughout the present-day hill landscape. In situ paleosols allowed to localize the paleo-topographic surfaces of geomorphic, tectonic and sedimentary stabilization; redeposited paleosols, occurring systematically close to the main faults and/or at the erosional bottom of paleo-valleys, allowed to mark the stages of tectonic instability. The integrated approach contributed to unravel the composite nature and rank of the stratigraphic boundaries.Polycyclic loess-soil aggradation characterized the stable paleo-highs, uplifted during different phases of active thrusting of the northernmost Emilian arcs of the Apennine, while valley incision, fluvial terracing, soil truncation and redeposition occurred in the intervening structural lows. In the San Colombano hill area, Late Pleistocene transtensional faulting induced changes of the drainage network and enhanced redeposition of paleosols in colluvial wedges on the hangingwalls, along the fault scarps. LGM loess was preserved above different dissected remnants of the paleo-topography composing the hilltops. These new constraints permit to refine the Late Quaternary tectono-depositional history and landscape evolution at the southern margin of the Po Basin. This paper focuses on three tectonic reliefs which are close to the southern Po Basin margin, at the Apennine side, that are the San Colombano, Casalpusterlengo and Zorlesco relic reliefs (Fig. 1). They provide comprehensive case-studies on how erosion/sedimentation processes, soil forming

Space–time geological model of the Quaternary syntectonic fill of a foreland basin (Po basin, Northern Italy)

“…At the same time, on the uplifting San Colombano hill, a wide erosion surface (S3.2) was cut and a palaeo-valley was incised and filled (CPS2a) then disactivated and abandoned before the deposition of the LGM L2 loess (Fig. 8G) in agreement with pedostratigraphic and morphological interpretations of Zuffetti et al (2018b), Zuffetti and Bersezio (2020).…”

“…It is apparent that the high-rank Synthem). The stable surfaces, uplifted on the three isolated hills, record pedogenesis (Cremaschi, 1987;Zuffetti et al, 2018b). All of these features suggest that the LGM and postglacial climate contributed to control unsteady deposition (Kim and Paola, 2007;Gunderson et al, 2014), competing with the ongoing uplift and collapse of the San Colombano hill (Figs.…”

“…8A). Where preserved, the top of the Synthem corresponds to a m-thick, rubified J o u r n a l P r e -p r o o f hydromorphic palaeosol (Zuffetti et al, 2018b) (soil profile 'a', Fig. 8A, B), otherwise it is truncated by S3.2 (Figs.…”

“…8G) (Zuffetti and Bersezio, 2020). At the glacial acme of MIS4, the L1 loess aggraded on the uplifted surfaces, then pedogenesis affected the morphological surfaces which developed above different stratigraphic units during the MIS3 interglacial (Zuffetti et al, 2018b). The…”

Hydrological Analysis of Loess Plateau Highland Control Schemes in Dongzhi Plateau

“…Loess systems are a key component of the delivery of many ecosystems, including those that are crucial to water and nutrient cycling. However, Loess systems are facing threats from soil erosion as a result of climate change and human engineering, which is a cause of worldwide concern (e.g., Van Andel et al, 1990;Butzer, 2005;Dreibrodt et al, 2010a;Starkloff and Stolte, 2014;Zuffetti et al, 2018;Mirzaee et al, 2020). Soil erosion brings disastrous consequences to local agricultural production and socio-economic development, affecting people's lives and property, and posing a significant threat to safety.…”