Climate and environmental changes recognized by micromorphology in Paleolithic deposits at Arene Candide (Liguria, Italy)

摘要

The lowermost part of the stratigraphic sequence of the Arene Candide Cave, a key Upper Palaeolithic site in Italy, attests to significant climate and environmental change at the beginning of the Late Pleniglacial in coastal Liguria (Northwest Italy). These archaeological layers were studied using a suite of mineral-ogical and chemical technique including a contextual sedimentological analysis (micromorphology). This study shows that the lower layers are dominated by cryoclastic sediments covered by cyclically organized blackish and reddish layers, or lenses. The black layers mainly consist of bird and bat guano deposits, interfingered with thin brownish sandy-silt layers of aeolian origin, that contain large amount of Ca phosphate. In contrast, the bright red layers are rubified sediment due to Fe re-oxidizing in insoluble form. In these layers evidence of syngenetic freeze-thaw cycles, associated with gelifluction processes, indicates a cool episode in a (semi) arid periglacial environment coupled to an increase in humidity between ca. 31 and 27 ka cal BP. Subsequently, the occurrence of features associated with repeated runoff and debris flow processes that caused a significant accumulation of poorly layered and sorted materials in the overlying sediments indicates a further intensification of humid conditions and reflects a longer phase of more humid and temperate climate. This change from arid to semiarid/humid climates resulted in an increase in sediments resulting from the erosion of Pliocene marine terraces and soils located outside the cave. The identification in the studied sequence of guano layers and the scarcity of artefacts, in conjunction with an absence of clear cultural micromorphological evidence, support an interpretation of sporadic human occupation of this part of the cave during Middle Upper Palaeolithic (Gravettian). Therefore, the finding in such a context of the lavish ceremonial burial of the so called "Young Prince" may suggest that the cave was used as a special place for burials at that time.