Reconstructing Mid-Late Holocene Arctic Climate Using Loess Deposits From Kangerlussuaq, Greenland

Abstract: The current geological epoch, the Holocene, began 11,700 years ago. During this time, a thermal maximum in temperature was reached somewhere during the early-middle stage at 8-5 kyrs ago which was followed by a period of neoglacial cooling, culminating in the little ice age (LIA). During this period of neoglacial cooling, the Greenland ice sheet (GrIS) experienced periods of advancement and retreat, which affected the local climate near the ice shelf. By looking at loess, a type of silt based wind-blown sediment, changes in stratigraphy can be used to correlate to changes in aeolian environment. The aim of this study is to determine what effects the neoglacial cooling had on the climate and if arctic loess can be used as a proxy to correlate climate change. This was done by using two methods of laboratory testing: grain size analysis and loss on ignition (LOI). Samples were gathered from Kangerlussuaq, Greenland in July 2021 from a 82cm deep loess-palaeosol section. The section consists of alternating loess and peat layers, indicating different depositional environments. The results show a general coarsening of the grainsize from the bottom upwards in the section, with reducing clay/silt content and increasing sand content, resulting in an overall increase in grain size mode. The LOI show a decrease in organic content from the bottom upwards. The increase of grain size mode and decrease of organic content in the loess is interpreted as being a result of changing climate at the sampling site. Previous studies have shown that the GrIS has had multiple distinct advancement events, which maybe can be correlated to the changes seen in the grain size and LOI data. A conclusion is drawn that the climate has changed due to the general cooling of temperature during deposition and glacial advancement, which leads to colder and harsher aeolian activity. This led to an increase in grainsize and reduction of organic content.