干旱区生态环境知识资源中心

The Pleistocene volcanic paleosols of Armenia and Mexico combine the features of both arid and humid pedogeneses. They were studied in order to reconstruct the environmental conditions during the period of the initial settlement of humans in these areas. The main attention was paid to the micromorphological analysis of the pedogenic features. The pedocomplexes studied in Armenia have been forming since the Early Pleistocene. They bear evidences of humid (weathering, clay illuviation, and gleying) and arid (calcification) pedogeneses alternating in different soil layers and pointing to climatic cycles. The nonuniform lithology of the soil profiles is related to pulsating volcanic activity. Mexican paleosols of the Late Pleistocene period are similar to the lower layers of the soils in Armenia with respect to the features characteristic of the humid and arid phases of pedogenesis. This allows us to suggest that the early stages of the formation of the Armenian pedocomplex proceeded under warmer paleoclimatic conditions similar to those of a tropical climate. It is shown that the arid pedogenesis may erase the features produced during the previous stage of humid pedogenesis. The studied paleosols are characterized by the destruction of the features inherited from the humid phase (the clayey groundmass and illuviation coatings) by the newly forming calcite. Paleopedological records point to the fact that the paleoenvironmental conditions during the periods of the initial settlement of humans in both regions differed significantly from the modern environmental conditions in these regions.