Holocene climate and environmental evolution in northeastern Iceland as recorded in the soil

• Main Author: Margrét Gísladóttir 1990-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: Jarðfræði; Viðarvatn; Iceland
• Online Access: http://hdl.handle.net/1946/39625

A soil section by Stóra Viðarvatn in northeastern Iceland, records environmental and climate changes during the Holocene (11.7 ka). The soil section contains several tephra layers that were studied to reconstruct an age model for the soil section. The tephra layers were traced back to their source volcanoes based on chemical composition, stratigraphy and by using bi-elemental discrimination plot. The age model provided information on soil accumulation rate (SAR), making it possible to calculate an approximate age of the tephra layers that proved difficult to trace back to their source volcano. The identification of tephra layers, SAR and grain size distribution make it possible to reconstruct environmental changes in the area based on comparison with proxy records from the nearby Stóra Viðarvatn sediment. The main results of this study reflect the result from the lake sediment and show sharp changes occurring around 9.3, 6.0, 4.0, 3.0, 1.4 and 0.5 ka, when changes in grain size distribution occurred indicating changes in the intensity in soil erosion. The slowest soil accumulation rate occurred between 4.0 and 3.0 ka when the greatest stability was reached but followed by an increase in landscape instability, suggesting cooling and windier times, which are related to the Neoglacial cooling of the Late Holocene. The soil erosion was most active around 0.5 ka and is potentially explained by the Little Ice Age cooling (LIA 1300-1900 CE), where cold and windy periods alternated with warmer periods in between. Jarðvegssnið við Stóra Viðarvatn á norðausturlandi, geymir sögu umhverfis- og loftslagsbreytinga á Nútíma (11.7 þús. ár). Jarðvegssniðið inniheldur fjölda gjóskulaga sem nýtast til aldursgreininga og myndun gjóskulagatímatals fyrir svæðið og sem hjálpa til við að tímasetja óstöðugleika í umhverfinu eins og jarðvegsrof. Hægt var að rekja gjóskulögin sem fundust í jarðvegssniðinu til uppruna síns og þar af leiðandi búa til aldursmódel, sem byggir á efnasamsetningu gjóskunnar og staðsetningu gjóskulaga í ...