WHEN A PEDOMARKER IS LACKING: PALYNOLOGICAL AND CHEMICAL MULTIANALYSIS OF A LATEGLACIAL-HOLOCENE SOILS SUITE (BOLOGNA)

Abstract

In 2014 a 13-metres long palaeopedological section has been sampled in the courtyard of Sant’Orsola Hospital (Bologna) to make a paleoenvironmental reconstruction of the area and to better understand the environmental dynamics occurring at the Chalcolithic site found at the depth of 5 metres. Pedological horizons have been grouped in 14 Soil Units (SU), 3 of which show a strong blackening. Chronological reference points are the 13230±70 cal. yr BP radiocarbon dated ACkb horizon of SU 10 (the lowest black horizon), the Chalcolithic charcoal horizon of SU 4 (the topmost) and the top-section Roman horizon of SU 1, the latter recognised thanks to some ceramic fragments. The other black horizon didn’t show specific characters on the field.Fossa Cavallina creek is the main driver of local depositional and environmental dynamics, while human presence is a subordinate factor. At first, geomorphological and chemical multianalysis have provided data to understand pedological conditions; secondly, palynological analysis has not only allowed to better characterise the environmental changes and their local drivers, but it also permitted to putatively assign the basal SU 14 to the Bølling interstadial, even though no diagnostic pedological features [AES 7b Vignola Unit’s A-Bw-Bt-Bk-C 2 m-thick reddish dark brown non calcareous Alfisol sensu Martelli et al. (editors), 2009] had been found. These results stress the striking importance of an integrated geomorphological, pedological and palynological approach towards the study of continental pedogenised deposits.

Keywords

• geochemistry
• pedology
• palynology
• Holocene
• Bologna