BURIED STEPPE SOILS IN S ITALY: A RECORD OF LAST GLACIAL ENVIRONMENTS

We present here a Last Glacial alluvial fan in Calabria (S Italy), exhibiting several alternating sedimentation and soil formation phases. The paleosols represent Chernozem- and Phaeozem-like soils that very likely formed in steppe to forest steppe environments under continental climatic conditions.

The same environmental conditions that are reflected in the paleosols have been reconstructed based on pollen records from Lago Grande di Monticchio. The latter indicate temperate deciduous forest from 87.98 to 82.73 ka; vegetation fluctuation from 82.73 to 59.00 ka, then Artemisia steppe; alternation between steppe (stadials) and wooded steppe (interstadials) from 59.00 to 25.90 ka; and again open steppe from 25.90 to 14.30 ka (LGM) (Brauer et al., 2007).

Organic matter of the two uppermost Lazzaro paleosols has been ¹⁴C-dated to 26.7-28.7 and 28.8-30.3 cal ka BP. Thus, the formation of these soils falls into a period for which the lacustrine record indicates an alternation between steppe and wooded steppe. It is still an open question whether the sedimentation that interrupted the ecologically stable times of soil formation was activated by fluctuations in climate and vegetation cover or by tectonics. The fact that pedogenesis falls into a period of frequent environmental oscillations suggests that the phases of sedimentation are to a certain degree driven by changes in climate and vegetation cover. More data on additional soil-sediment profiles are required to check if paleopedological, lacustrine and marine records can be correlated to obtain an integral reconstruction of paleo-climate, -vegetation, -geomorphodynamics and -pedogenesis in the region.

The soils were analyzed for texture, SOC, carbonates, Fe_d, total elemental composition and micromorphology. Fe_d values reflect pedogenetic cycles in the alluvial fan more clearly than SOC contents, which are not as high in the paleosols as might be expected according to their dark color. We conclude that Chernozem- and Phaeozem-like soils developed during the Last Glacial period in South Italy in steppe and forest steppe environments. These soils have been preserved only where they had been buried before the climate shifted again to Mediterranean type. Otherwise SOM of the thick mollic A horizons decomposed, and the soils turned into Mediterranean-type soils.