ESTUDOS BIOGEOQUÍMICOS NO COMPLEXO BÁSICO-ULTRABÁSICO DE PEDRAS PRETAS, SÃO SEPÉ, RS.

Resumo

Biogeochemical studies in the arca of the Basic-Ultrabasic Complex of Pedras Pretas, São Sepé, RS, reveal that the occurrence of a dwarf shrub vegetation is related to the presence of elements usually found in gabbroic and peridotitic lithologies which characterize this complex. The results of leaf-ash analyses of Scutia buxifolía indicate that this species is tolerant to high contents of Nickel, making it a biogeochemical indicator for this element in the studied area. The predominance of thís plant is attesded by its adaptation capacity to soils depleted in essential nutrients, with low Ca/Mg ratio. The plant, as well as the rock and soil geochemistry, proves the existence of a nickeliferous environment usually associated with serpentinized areas.