Pollen spectra in Holocene ice wedges in the floodplain of the Lyakkatosyo River (Eastern Yamal, Russia)

Study considers horizontal and vertical sampling directions for pollen analysis of ice wedges, taking into account the special mechanism of wedge ice formation. Pollen spectra from the Late Holocene ice-wedges on high polygonal floodplain of the Lyakkatosyo River are studied. Shrub-lichen-moss-polygonal tundra dominates the site. We accounted for the number of elementary veins. The main research methods are pollen and geochemical analyses. We collected samples for pollen analysis along ice wedges' axis and horizontally at depth of 1.20 m, while we also took samples for chemical analysis along the same axis. The high concentration of pollen and spores in ice wedges made it possible to compare results of horizontal and vertical sampling with sufficient degree of accuracy. Pollen spectra characterizing ice wedge horizontally and vertically showed significant differences in the main components. The main difference between horizontal and vertical pollen spectra in AP is the spruce and birch pollen percentages. Along the ice wedge axis, spruce pollen (2.0–13.0%) and birch pollen (6.0–14.0%) are always visible. However, we only find spruce pollen (2.0–4.0%) up to 0.3 m from the vein axis and birch pollen (2.0–14.0%) up to 0.4m from the vein axis. We detected similar-composition pollen spectra in only one case. The sample that is closest to the center of the ice wedge, located at 0.1 m from axis and at depth of 1.2 m, exhibits approximately the same pollen spectra as the sample that is located at depth of 1.2 m from the central part of ice wedge. It is quite natural that certain pollen taxa do not have a general sequence of culminations. Chemical composition of ice wedge suggests that spruce pollen got into the ice due to flooding of the Lyakkatosyo River.

polygonal landscapes, ice wedge, permafrost, macroelements, pollen, spores, pollen grain concentration, flood plain, Lekatosyo River, Yamal Peninsula