Climate variability and glacial processes in eastern Iceland during the past 700 years based on varved lake sediments

TY - JOUR

T1 - Climate variability and glacial processes in eastern Iceland during the past 700 years based on varved lake sediments

AU - Striberger, Johan

AU - Björck, Svante

AU - Ingólfsson, Ólafur

AU - Kjær, Kurt H.

AU - Snowball, Ian

AU - Uvo, Cintia B.

PY - 2011/1

Y1 - 2011/1

N2 - Properties of varved sediments from Lake Lögurinn in eastern Iceland and their link to climate and glacial processes of Eyjabakkajökull, an outlet glacier of the Vatnajökull icecap, were examined. A varve chronology, which covers the period AD 1262-2005, was constructed from visual observations, high-resolution images, X-ray density and geochemical properties determined from X-radiography and X-ray fluorescence scanning. Independent dating provided by 137Cs analysis and eight historical tephras verify the varve chronology. The thickness of dark-coloured seasonal laminae, formed mainly of coarser suspended matter from the non-glacial river Grímsá, is positively correlated (r=0.70) with winter precipitation, and our 743-year-long varve series indicates that precipitation was higher and more varied during the later part of the Little Ice Age. Light-coloured laminae thickness, controlled mainly by the amount of finer suspended matter from the glacial river Jökulsáí Fljótsdal, increased significantly during the AD 1972 surge of Eyjabakkajökull. As a consequence of the surge, the ice-dammed Lake Háöldulón formed and recurrently drained and delivered significant amounts of rock flour to Lake Lögurinn. Based on these observations, and the recurring cyclic pattern of periods of thicker light-coloured laminae in the sediment record, we suggest that Eyjabakkajökull has surged repeatedly during the past 743 years, but with an increased frequency during the later part of the Little Ice Age.

AB - Properties of varved sediments from Lake Lögurinn in eastern Iceland and their link to climate and glacial processes of Eyjabakkajökull, an outlet glacier of the Vatnajökull icecap, were examined. A varve chronology, which covers the period AD 1262-2005, was constructed from visual observations, high-resolution images, X-ray density and geochemical properties determined from X-radiography and X-ray fluorescence scanning. Independent dating provided by 137Cs analysis and eight historical tephras verify the varve chronology. The thickness of dark-coloured seasonal laminae, formed mainly of coarser suspended matter from the non-glacial river Grímsá, is positively correlated (r=0.70) with winter precipitation, and our 743-year-long varve series indicates that precipitation was higher and more varied during the later part of the Little Ice Age. Light-coloured laminae thickness, controlled mainly by the amount of finer suspended matter from the glacial river Jökulsáí Fljótsdal, increased significantly during the AD 1972 surge of Eyjabakkajökull. As a consequence of the surge, the ice-dammed Lake Háöldulón formed and recurrently drained and delivered significant amounts of rock flour to Lake Lögurinn. Based on these observations, and the recurring cyclic pattern of periods of thicker light-coloured laminae in the sediment record, we suggest that Eyjabakkajökull has surged repeatedly during the past 743 years, but with an increased frequency during the later part of the Little Ice Age.

U2 - 10.1111/j.1502-3885.2010.00153.x

DO - 10.1111/j.1502-3885.2010.00153.x

M3 - Journal article

SN - 0344-810X

VL - 40

SP - 28

EP - 45

JO - Boreas

JF - Boreas

IS - 1

ER -