The Lithological and Geochemical Features and Paleoclimatic Conditions for the Formation of the Verkhnyaya Lena Group (Southeast of the Siberian Platform)

Abstract

The Verkhnyaya Lena Group (Є_2–3vl) has been studied in a section on the right bank of the Malaya Chuya River. Concentrations of main oxides and some trace elements (Cr, V, Ni, Cu, Zn, Rb, Sr, Zr, Ba, U, Th, Y, Nb, and Cl) have been determined in samples using an X-ray spectral fluorescence (XRF) analysis. The normative mineral composition has been determined based on the results of the XRF analysis using the MINLITH software. Based on geochemical data, intervals of change in the weathering features (physical/chemical and arid/humid weathering) are clearly differentiated in the denudation area, which are fixed by variations in the values of the Al₂O₃/K₂O and Ln(Al₂O₃/Na₂O) ratios and concentrations of V, Cu, Zn, Rb, and Ni, as well as the normative mineral composition. Apparently, Cr was transported to the basin exclusively by the aeolian process in this case and marks periods of increased wind transport intensity. Under conditions of tectonic activation and progressive isolation of the Upper Lena paleobasin, the described lithological and geochemical features provide some information about the climate changes that accompanied these events.