Genesis and climatic interpretation of paleosols and calcretes in a plio-pleistocene alluvial fan of the costa blanca (SE Spain)

摘要

A Plio-Pleistocene alluvial fan near La Regia, in the southeast coast of Spain contains a vertical series of 7 fossil soils and 7 calcrete complexes. The soil stratigraphy reflects recurring alternation of sedimentation and soil formation suggesting numerous, pedogenically effective cyclical climatic changes during the Late Pliocene and Early Pleistocene. The differentiated composition of calcretes near La Regia is a polygenetic product: Surface erosion and sedimentary fossilization were followed by secondary carbonatization and subsequent induration. At least 15 stages of soil formation are reconstructed. Red paleosols and pedogenic calcretes are well developed and reflect humid subtropical and Mediterranean conditions during soil genesis with geomorphodynamic stability. In contrast, the accumulation of sediments and synsedimentary calcretes correlates with geomorphodynamic activity under considerably drier Mediterranean conditions.