We present the results of a comprehensive lithologic and mineralogical study of Late Holocene bottom sediments from the meromictic Lake Shira in the North Minusinsk Basin (Republic of Khakassia, Southern Siberia). The methods include X-ray diffractometry (XRD), IR spectroscopy, laser particle-size analysis, and radiocarbon dating. Over the past ~3000 years, intensive authigenic carbonate formation has occurred in the lake, and gypsum has also been observed. For the first time, the differential identification of authigenic carbonates in Lake Shira sediments was performed using mathematical modeling of X-ray diffraction patterns. Their structural and crystallochemical features, as well as quantitative ratios, were determined in the section. It has been established that the assemblage of carbonate minerals in the studied sediments comprises Ca–Mg trigonal varieties (calcite, Mg calcites with varying Mg content, and Ca-excess dolomite), aragonite, and monohydrocalcite. The leading role of calcite–dolomite series carbonates as paleoclimate indicator minerals in the sedimentary records of salt lakes is substantiated. Based on these studies, the evolution of natural and climatic conditions in the northern Minusinsk Basin was reconstructed, and periods of aridization/humidification of the regional climate in the Late Holocene were identified.
Солотчин et al. (Fri,) studied this question.