Physico-chemical parameters of sediment core PG1975-1 (09-Tik-05) from a Tundra Lake, Northeastern Siberia

The relationships between thermokarst activity, limnogeological processes and climate change in the Siberian Arctic are not well understood. The objective of this paper is to identify the factors controlling the patterns of deposition, using grain size distribution, organic content, elemental composition and mineralogical composition of a 137-cm long sediment core with a maximum age of ~10.9 cal. kyr BP from Lake El'gene-Kyuele in the tundra of northeastern Siberia. Eight fine sand layers are attributed to depositional events associated with thaw slump activity acting upon orthogonally oriented patterns of ice-wedge networks in the ice-rich permafrost on the NW margin of the lake catchment. Sr/Rb ratios, which correspond to the total feldspar and illite content, serve as high-resolution grain size proxies. The Br content relates to the total organic carbon content, and the Fe/Mn ratio reflects the degree of oxidisation. Our results indicate a relationship between repeated phases of fine sand input and retrogressive thaw slumping dependent on hydroclimate variability and orthogonally oriented ice-wedge networks within the catchment.

北极西伯利亚地区的热喀斯特活动（thermokarst activity）、湖沼地质过程（limnogeological processes）与气候变化之间的关联尚未得到充分阐明。本研究旨在通过分析西伯利亚东北部苔原带埃尔金-库耶勒湖（Lake El'gene-Kyuele）一根长137厘米、最大定年年龄约为10.9校准千年BP（cal. kyr BP）的沉积岩芯（sediment core）的粒度分布、有机质含量、元素组成及矿物组成，识别控制沉积格局的影响因素。研究将湖盆西北缘富冰多年冻土（ice-rich permafrost）中正交型冰楔网络（ice-wedge networks）上发生的融滑塌（thaw slump）活动相关的沉积事件，归因于8层细砂沉积层。锶/铷（Sr/Rb）比值对应总长石（feldspar）与伊利石（illite）含量，可作为高分辨率粒度代用指标（grain size proxies）。溴（Br）含量与总有机碳（total organic carbon）含量相关，而铁/锰（Fe/Mn）比值则反映氧化程度（oxidisation）。本研究结果表明，细砂输入的重复阶段与后退式融滑塌（retrogressive thaw slumping）之间存在关联，该关联受流域内水文气候变化（hydroclimate variability）及正交型冰楔网络的调控。