Herein, we present a synthetic study combining iron (Fe) speciation and biomarkers in sediment samples from Luguhu Lake to investigate their relationship and the environmental significance thereof. Mössbauer spectroscopy and gas chromatography–mass spectrometry were used for these measurements. The results suggest that (a) there is a strong negative correlation between Fe2+/Fe3+ and the ratio of pristane to phytane (Pr/Ph), indicating that both Fe2+/Fe3+ and Pr/Ph effectively present the inorganic and organic aspects, respectively, of the oxidation–deoxidation environment in Luguhu Lake; (b) palaeotemperature may be a factor, in addition to the redox conditions, that affects the Fe2+/Fe3+ ratio, and it might play a favourable role in studies of palaeotemperature; and (c) the relative abundance of Fe in Luguhu Lake is affected by the palaeoclimate and the environment in which the palaeosediment was deposited. The mechanism of change in the total area (the total absorption area of Mössbauer spectrum) with the palaeoenvironment seems to be explained by the loss of Fe, which occurs as the water drains out of the lake, and the increase in Fe loss from the sediment as rainfall levels increase.

A massive ground-ice body was found exposed in the headwall of a thaw flow developed within the Chapman Lake terminal moraine complex on the Blackstone Plateau (Ogilvie Mountains, central Yukon Territory), which is contemporaneous to the Reid glaciation. Based on visible cryostructures in the 4-m-high headwall, two units were identified: massive ground ice, overlain sharply by 2 m of icy diamicton. The nature and origin of the Chapman Lake massive ground ice was determined using cryostratigraphy, petrography, stable O–H isotopes and the molar concentration of occluded gases (CO2, O2, N2 and Ar) entrapped in the ice, a new technique in the field of periglacial geomorphology that allows to distinguish between glacial and non-glacial intrasedimental ice. Collectively, the results indicate that the Chapman Lake massive ground ice formed by firn densification with limited melting–refreezing and underwent deformation near its margin. Given that the massive ground-ice body consists of relict glacier ice, it suggests that permafrost persisted, at least locally, on plateau areas in the central Yukon Territory since the middle Pleistocene. In addition, the d value of Chapman Lake relict glacier ice suggests that the ice covering the area during the Reid glaciation originated from a local alpine glaciation in the Ogilvie Mountains.

Despite being a key location for paleoglaciological research in north-central Asia, with the largest number of modern and Pleistocene glaciers, and in the transition zone between the humid Russian Altai and dry Gobi Altai, little is known about the precise extent and timing of Holocene and late Pleistocene glaciations in western Mongolia. Here we present detailed information on the distribution of modern and late Holocene glaciers, and new results addressing the geomorphological differentiation and numerical dating (by optically stimulated luminescence, OSL) of Pleistocene glacial sequences in these areas. For the Mongolian Altai, geochronological results suggest large ice advances correlative to marine isotope stages (MIS) 4 and 2. This is in contrast to results from the Khangai mountains, central Mongolia, showing that significant ice advances additionally occurred during MIS3. During the Pleistocene, glacial equilibrium-line altitudes (ELAs) were ~500 to >1000m lower in the more humid portion of the Russian and western Mongolian Altai, compared to 300-600 m in the drier ranges of the eastern Mongolian Altai. Pleistocene ELAs in the Khangai mountains were depressed by 700-1000 m, suggesting more humid conditions at times of major glaciation than in the eastern Mongolian Altai. This paleo-ELA pattern reveals that the precipitation gradient from the drier to the more humid regions was more pronounced during glacial times than at present.