Geophysical processes and biosphere: article

Аnnotation: With a purpose of investigation of geoecologic and paleogeographic peculiarities of existence and development of high-mountain lakes we have conducted field study of geological sections of loose deposits in western part of the Sevan lake depression (Armenia). In the results of investigations of mentioned sections we have revealed characteristic lithologic signatures of significant lake transgressions, stratigraphic layers with numerous remnants of human activity, as well as traces of ancient earthquakes - horizons of seismogenic convolutions in lacustrine deposits (seismites). For a determination of absolute age of mentioned stratigraphic units we used 4 radiocarbon dates obtained at Radiocarbon Laboratory of Lomonosov Moscow State University from samples from geological section near Norashen village. They gave accurate ages of the lacustrine deposits in age interval of 2020±120 - 6270±110 years BP for the section of 4.5 m thickness. Using these data we have calculated average rate sedimentation in studied region - 0.34 mm/year. Materials of the radiocarbon dating of the lacustrine deposits have demonstrated two significant lake transgressions: in Middle and Late Holocene. During field study a special attention were paid to a section of lacustrine deposits near Norashen village because there were found layers with significant consistence of remnants of men life: ceramics and bones. Archeological investigations and radiocarbon dates of the Norashen section have shown that this region was occupies be the men twice: in 3rd and middle 2nd centuries BC. Analysis of data of the study of seismogenic convolutions in the lacustrine deposits has brought us to a conclusion about possible tie of transgressions regime and 500-years break in men occupation of the study region with a strong earthquake in the Sevan lake depression occurred approximately 4400 years ago. Obtained data can be used for determination of long-term trend of high-mountain lake’s oscillation in Holocene and revealing its causes, as well as for more precise assessment of the seismic hazard in western part of the Sevan lake depression.