New data on the structure of the loess-soil series of Tajikistan

The object of the study is the loess-paleosol sections Khonako-۲ and Khonako-۳, located ۷ km northeast ofthe Khovaling town (Khovaling District of Tajikistan). These sections are part of a two-kilometer-long loesspaleosoloutcrop ~۱.۵ million years old, which contains, according to various authors (Dodonov, ۱۹۸۴;Ranov, ۱۹۹۵), from ۱۲ to ۲۴ paleosols separated by loess horizons. Khonako-۲ is notable for its geologicalcompleteness, up to ۲۴ PC are traced here, but there are very few archaeological finds (fig ۱). The Honako-۳ section is rich in artifacts, but the natural outcrop is limited to ۴ PC. The loess-soil sections of Tajikistanrepresent a unique paleogeographic archive containing information on the stages of glaciations andinterglacials. The aim of this work is to obtain new data on the petromagnetic characteristics of the loesssoilseries composing the reference loess-soil series sections of the Khonako-۲ and Khonako-۳ of Tajikistan.Unique finds from a number of cultural horizons have been described in the alternating loess and paleosolhorizons of the region During the field work, section was prepared for study, all the geological section weredescribed, the magnetic susceptibility of loess in the upper part (۴۰.۸ m) of the Khonako-۲ section and theupper part of the Khonako-۳ (۳۶.۱ m) was measured using a KT-۵ field cappameter. Measurements weretaken continuously along the Honako-۲ and Honako-۳ transects by scraping vertical walls, which weresubdivided into intervals of ۸۰-۱۵۰ cm. Then, visualization of the obtained measurement results wasperformed, which included highlighting the peaks on the plots, and subsequent preliminary interpretationof the data (in particular, correlation with MIS). In the Khonako-۲ and Khonako-۳ sections, measurementsof magnetic susceptibility allowed us to distinguish ۵ stages of sedimentation - development of the naturalenvironment. The warming epochs recorded in series of paleosols united into pedocomplexes. The warminterglacial stages corresponding to paleosols and highlighted in the studied sections according to magneticmeasurements most likely correspond to MIS-۵ and MIS-۷. Magnetic susceptibility data from the Khonako-۲ and Khonako-۳ sections clearly distinguish periods corresponding to warming and cooling phases;identified warming stages correspond to pedocomplexes ۱ and ۲, which, presumably, correlate with MIS-۵and MIS-۷. The report will present data on the structure of sediments, the character of changes in magneticsusceptibility in sections, and discuss the importance of these data for studying the evolution of the naturalenvironment of western Central Asia in the Middle and Late Pleistocene. The obtained data made itpossible to perform a preliminary correlation of PK۱ with MIS-۵ and PK۲ with MIS-۷.

کلیدواژه ها:

paleomagnetology ، paleoclimatology ، petromagnetic characteristics