Phytolith analysis of light-humus stratozem genesis (the case of the Bagan lakeside territory)

The purpose of our work was to define the evolution of soil lakeside area on the basis of archive paleolandscape information associated with the formation of light-humus stratozem. We carried out the studies in the North Kulunda lacustrine-alluvial plain located in the southern part of the West Siberian lowland within the Ob-Irtysh interfluve. We defined the conditions of light-humus stratozem forming under water regime changing of Lake Bagan, using microbiomorphic analysis data by the method of A Golyeva. Microbiomorphic analysis means studying microresidues of biota leaving its traces in stratozem layers. Microbiomorphs include diatoma residues and small crawfish and plant shells. Silicated plant residues, i.e. phytholiths, are deposited in soil and reflect conditions of their forming. Plants of specific ecological groups form their phytholith complexes and differ in shape and size. According to the field researches of soil profile morphological features, light-humus stratozem has complex profile composition and looks like interchange of horizons and layers formed after fresh material adding and depositing on the buried profile of light saline soil. Physical and chemical stratozem analysis data show accumulative character of total carbon distribution with maximum accumulation in sod cover where carbon amount is 3.5% with its gradual decreasing to 0.3%. Medium reaction changes from neutral (pH _water=6.6) in the upper layers to alkaline one (pH _water=8.5) in the accumulative-carbonate horizon. The upper layer of RJ1 stratified horizon has weak-acid medium reaction (рИ _water=6.2). In granulometric composition soil profile is of binomial structure that is referred to specific synlithogenic stage of its forming. The profile upper part corresponding to alluvium (0-45 cm) is sandy and sandy-loam. The lower part (below 45 cm) is just buried soil of loamy and heavy loamy granulometric composition. Taking into account the research results, we can conclude that water-accumulative light-humus stratozem was formed under complicated dynamic conditions. After flood forming period some stage changes occur with lake water table ebb and flow and steppe and reed complexes form. Acknowledgments: This work was partially supported by International Project № 220 «BIO-GEO-KLIM».

Keywords

Authors

References