The caranto paleosol and its role in the early urbanization of Venice

Abstract

As rising sea level threatens Venice, there is a need to construct a historical framework for interpreting modern environmental changes. Environmental conditions that would later help support Venice's urbanization were established during the Late Glacial period when calcic soils began to develop in the Venetian alluvial paleoplain. A calcic paleosol, buried by Middle to Late Holocene marine transgressive deposits, represents a subsurface layer long known in the Venice area as "caranto." Referenced in the ancient chronicles of architects and builders, the caranto exhibits relatively high compressive and shear strength, making it an important substrate for supporting building foundations, some dating back to the Gothic era (12th-15th centuries A.D.). Hence, the caranto paleosol documents local post-glacial environmental changes while playing an important role in Venetian building construction and human settlement. Here we provide geochemical, sedimentological, paleoecological, and chronological analyses of the caranto paleosol and related deposits based on recent coring of the Venetian Lagoon.

Saltwater contamination in the managed low-lying farmland of the Venice coast, Italy: An assessment of vulnerability

“…The Late Pleistocene sedimentary deposits consist of an aggrading floodplain facies with fluvial channels fills accumulated during the decrease of the sea level, and are composed by silts, sands, and clays, frequently pedogenesized (Tosi et al, 2007a;Donnici et al, 2011;Zecchin et al, 2011). The boundary with the overlying Holocene units is often characterized by the presence of a paleo-soil, locally named Caranto, developed in prolonged subaerial exposure and sedimentation starving conditions.…”

Three Geostatistical Methods for Hydrofacies Simulation Ranked Using a Large Borehole Lithology Dataset from the Venice Hinterland (NE Italy)

“…Especially on cross-sections, it is apparent that SIS tends to render less fuzzy and noisy facies clusters compared to TGS (cfr. Figure 6c,e), which at densely investigated sites (e.g., the Petrolchimico) results in faithful reproduction (compare Figure 3b with sections on left-hand side of Figure 6e) of interpreted lithofacies distributions [26]. Cleaning SIS realizations from noise with the same settings used for TGS results in crispier facies cluster's boundaries (Figure 6f) with very little impact on facies proportions (Figure 7).…”

“…However, it was possible to rank the tested algorithms based on how closely they honored input data and predicted facies at validation boreholes [11], as well as they replicated the current hydrostratigraphic model of the study area [26]. Even though resulting in geologically realistic facies distributions, the Object-Based Simulation (OBS) of this study failed to achieve full conditioning to boreholes, as well as to reproduce global and layer-by-layer facies proportions.…”

“…Because LGM deposits were not buried by younger deposits over most of the Venice's hinterland, the present-day landscape of the study area represents the relic morphology of BRM. This consists of a plain with topographic gradients in the range 0.4-2‰ crossed by a series of The deglaciation following the Würm Last Glacial Maximum (LGM; 26-19 kyr BP) resulted in a dramatic decrease of sediment supply to megafans with consequent pedogenization and development of the 'Caranto' paleosol [26], as well as a swift sea level rise and landward shift of coastal depositional environments. The shallow subsurface stratigraphy of the model area comprises, from top to bottom: (i) a rather thin (typically a few meters) and discontinuous layer of anthropogenic deposits, reaching a maximum thickness of ca.…”

“…Object-Based Simulation (OBS) is suitable when boreholes are sparse but ancillary observations (e.g., geophysics) provide information on geobodies' shape and lithofacies [12][13][14]. OBS populates The deglaciation following the Würm Last Glacial Maximum (LGM; 26-19 kyr BP) resulted in a dramatic decrease of sediment supply to megafans with consequent pedogenization and development of the 'Caranto' paleosol [26], as well as a swift sea level rise and landward shift of coastal depositional environments. The shallow subsurface stratigraphy of the model area comprises, from top to bottom: (i) a rather thin (typically a few meters) and discontinuous layer of anthropogenic deposits, reaching a maximum thickness of ca.…”