Structure and conditions for the formation of the sediments section of new multilayer Geoarchaeological Site Kitoi Most (Late Upper Paleolithic, Cis-Baikal)

Archaeological sites of the Middle Sartan age are extremely rare within the Cis-Baikal region, and therefore are of a great interest to specialists. Our team discovered a new multi-layered geoarchaeological object of this age, called the Kitoi Most. The paper presents the results of comprehensive studies of the deposits hosting culture-bearing horizons at Kitoi Most. The section has a complete set of regional chronostratigraphic levels of the Upper Pleistocene. Sediments derived from the rocks of the Jurassic sedimentary basin. At the initial stage (MIS 5), the formation of the section occurred in alluvial environment, and subsequently (MIS 4–1) mainly in subaerial conditions with periodic manifestations of pedogenesis and an increased role of colluvial processes. The formation of the magnetic properties of deposits of the loess strata of the section corresponds to the “Siberian” mechanism, which is a superposition of two “Chinese” mechanisms, which explains the presence of superparamagnetic particles in soils as a result of pedogenesis, and the “Alaskan” (wind) mechanism, which causes differences in the magnetic susceptibility of loess and fossil soils by changes in the intensity of wind activity. In the subaerial deposits of the Sartan (MIS 2) age, the presence of nivean-eolian sands was established. These deposits overlap archaeological horizons and correspond to ~17–14.7 ka cal. BP period when sediment genesis was influenced by deep cryoaridization with the manifestation of extremely strong wind. Apparently, this climatic pressure influenced development of the system of human occupation in the region, which is currently expressedin the limited distribution of archaeological objects of this age in the territory of Cis-Baikal.

1. Beget J.E., Stone D.B., Hawkins D.B. (1990) Paleoclimatic forcing of magnetic susceptibility variations in Alaskan loess during the Late Quaternary. Geology. Vol. 18. P. 40-43.

2. Berdnikova N.E., Berdnikov I.M., Vorobyova G.A. et al. (2021) Middle and late stages of the Upper Paleolithic of Baikal-Yenisei Siberia: chronology and general characteristics. Izvestia Irkutskogo Universiteta. Series Geoarchaeology. Ethnology. Anthropology. Vol. 38. pp. 59-77. (in Russ.) https://doi.org/10.26516/2227-2380.2021.38.59

3. Berdnikova N.E., Zolotarev D.P., Berdnikov I.M. et al. (2024) Archaeological complexes of the Kitoi Most site in the context of the Upper Paleolithic of Baikal-Yenisei Siberia. Archeologicheskie Vesty. No. 42. P. 84-99. (in Russ.) https://doi.org/10.31600/1817-6976-2023-42-84-99

4. Brookfield M.E. (2011) Aeolian processes and features in cool climates. Geol. Soc. London Spec. Publ. P. 241-258.

5. Condie K.C. (1993) Chemical composition and evolution of the upper continental crust: contrasting results from surface samples and shales. Chemical Geology. Vol. 104. P. 1-37.

6. Cox R., Lowe D.R., Cullers R.L. (1995) The influence of sediment recycling and basement composition on evolution of mudroc chemistry in southwrstern United States. Geochim. Cosmochim. Acta. Vol. 59. P. 2919-2940.

7. Dinwiddie C.L., McGinnis R.N., Stillman D.E. (2012) Internal sedimentary structure and aqueous-phase distribution of the Great Kobuk Sand Dunes, northwestern Alaska: Insights from an arctic aeolian analog site. In: Third Intern. Planetary Dunes Workshop: Remote Sensing and Image Analysis of Planetary Dunes. Flagstaff: Arizona publ. abstr. No. 7034.

8. Evans M.E., Heller F. (2003) Environmental Magnetism. New York: Academic Press. 299 p.

9. Filippov A.G., Erbaeva M.A., Khenzykhenova F.I. (1995) Use of Upper Cenozoic small mammals of the south of Eastern Siberia in stratigraphy. Irkutsk: VostSibNIIGGiMS. 117 p. (in Russ.)

10. Galanin A.A. (2021) Late Quaternary sand covers of Central Yakutia (Eastern Siberia): structure, facies composition and paleoecological significance. Cryosphere of the Earth. Vol. XXV. No. 1. P. 3-34. (in Russ.)

11. Gradzinski R., Kostecka A., Radomski A. (1980) Sedimentology. Moscow: Nedra. 640 p. (in Russ.)

12. Herron M.M. (1988) Geochemical classification of terrigenous sands and shales from core or log data. J. Sediment. Petrol. Vol. 58. P. 820-829.

13. Ivanova V.V., Shchetnikov A.A., Filinov I.A. et al. (2016) Lithological and geochemical features of deposits of the Ust-Oda reference section of the Upper Neopleistocene of the Irkutsk amphitheater of the Siberian plastic forms. Lithology and mineral resources. Vol. 51. No. 3. P. 215-232. https://doi.org/10.7868/S0024497X16030022

14. Jasonov P.G., Nourgaliev D.K., Bourov B.V. (1998) A modernized coercivity spectrometer. Geologica Carpathica. Vol. 49. No. 3. P. 224-226.

15. Kalinin P.I., Alekseev A.O., Savko A.D. (2009) Loess, paleosols and paleogeography of the Quaternary of the southeast of the Russian Plain. Proceedings of the Scientific Research Institute of Geology of VSU. Vol. 58. 139 p. (in Russ.)

16. Kazansky A.Yu., Matasova G.G., Shchetnikov A.A. et al. (2013) Correlation between magnetic and granulometric parameters in Quaternary deposits of the Ust-Oda reference section (Pre-Baikal region). In: Paleomagnetism and magnetism of rocks. Theory, practice, experiment. Kazan: KSU Publishing House. P. 95-102. (in Russ.)

17. Kazansky A.Yu., Matasova G.G., Shchetnikov A.A. et al. (2022) The Kitoi Bridge section is a new type of section of the Upper Quaternary sediments of the Cis-Baikal region. In: Geodynamic evolution of the lithosphere of the Central Asian mobile belt (from ocean to continent). Irkutsk: IEC SB RAS. P. 117-119. (in Russ.)

18. Kirschvink J.L. (1980) The least squares line and plane and the analysis of paleomagnetic data. Geophys. J. Roy. Astron. Soc. Vol. 62. P. 699-718.

19. Maslov A.V. (2005) Sedimentary rocks: methods for studying and interpreting the data obtained. Ekaterinburg: UGGU Publishing House. 289 p. (in Russ.)

20. Matasova G., Kazansky A.Y. (2004) Magnetic properties and magnetic fabrics of Pleistocene loess/palaeosol deposits along west-central Siberian transect and their palaeoclimatic implications. Geol. Soc. London. Vol. 238, P. 145-173. https://doi.org/10.1144/GSL.SP.2004.238.01.11

21. Medvedev G.I. (1983) Paleolithic of the Southern Angara region. PhD thesis. Novosibirsk: NSU. 44 p. (in Russ.)

22. Mikheeva E.A. (2017) Age boundaries, correlation, sources and areas of provenance of Jurassic deposits of the Irkutsk basin. PhD thesis. Irkutsk: IEC SB RAS. 28 p. (in Russ.)

23. Mikheeva E.A., Demonterova E.I., Frolov A.O. et al. (2017) Change of sources of demolition of the Irkutsk coal basin during the Early and Middle Jurassic according to geochemical and Sm–Nd isotope data. Stratigraphy. Geological correlation. Vol. 25. No. 4. P. 3-25.

24. Nesbitt H.W., Young G.M. (1982) Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature. No. 299 (5885). P. 715-717.

25. Nordt L.C., Driese S.D. (2010) New weathering index improves paleorainfall estimates from Vertisols. Geology. Vol. 38. No. 5. P. 407–410.

26. Raukas A.V. (1981) Classification of clastic rocks and sediments by granulometric composition. Tallinn: Institute of Geology of the Academy of Sciences of the Estonian USSR. 24 p. (in Russ.)

27. Retallack G.J. (2001) Soils of the Past: an Introduction to Paleopedology. Oxford: Blackwell. 600 p.

28. Retallack G.J. (2003) Soils and Global Change in the Carbon Cycle over Geological Time. Treatise on Geochemistry. Vol. 5. P. 1- 28. https://doi.org/10.1016/B0-08-043751-6/05087-8

29. Shchetnikov A.A., Bezrukova E.V. Maksimov F.E. et al. (2016) Environmental and climate reconstructions of the Fore-Baikal area during MIS 5-1: Multiproxy record from terrestrial sediments of the Ust-Oda section (Siberia, Russia). Journal of Asian Earth Sciences. Vol. 129. P. 220-230. https://doi.org/10.1016/j.jseaes.2016.08.015

30. Stratigraphy, paleogeography and archeology of the south of Central Siberia. In: To the XIII Congress of INQUA (1990). Irkutsk: Irkutsk Publishing House. 165 p. (in Russ.)

31. Tauxe L. (2010) Essentials of Paleomagnetism. University of California Press: Berkeley. 512 p.

32. Taylor S.R., McLennan S.M. (1988) Continental crust: its composition and evolution. M.: Mir. 384 pp.

33. Turgeon S., Brumsack H.J. (2006) Anoxic vs dysoxic events reflected in sediment geochemistry during the Cenomanian Turonian Boundary Event (Cretaceous) in the Umbria Marche Basin of central Italy. Chemical Geology. Vol. 234. P. 321-339. https://doi.org/10.1016/j.chemgeo.2006.05.008

34. Vorobyova G.A. (2016) Igetey - a key geoarchaeological object of the Baikal region: climatostratigraphy, pedogenesis, subaerial sedimentation, composition and paleoecological significance. In: Esse quam videri: To the 80th anniversary of the birth of German Ivanovich Medvedev. Irkutsk: ISU Publishing House. P. 152-166. (in Russ.)

35. Vorobieva G., Vashukevich N., Berdnikova N. et al. (2021) Soil Formation, Subaerial Sedimentation Processes and Ancient Cultures during MIS 2 and the Deglaciation Phase MIS 1 in the Baikal–Yenisei Siberia (Russia). Geosciences. Vol. 11. P. 323-335. https://doi.org/10.3390/geosciences11080323

36. Yudovich Ya.E., Ketris M.P. (2000) Fundamentals of lithochemistry. St. Petersburg: Nauka. 479 p. (in Russ.)

37. Zijderveld J.D.A. (1967) Demagnetization of rocks: analysis of results / In: Methods in paleomagnetism. Elsevier: Amsterdam. P. 254-286.