The Depositional History of the Younger Dryas-Preboreal Búdi Moraines in South-Central Iceland

Abstract

Detailed sedimentological analysis of the Búdi morainal complex in south-central Iceland records a rapid accumulation within marine-, coastal, and glacial environments during a recessional phase of the glaciers within the Preboreal chronozone. Three principal outcrop areas are characterized by stratified diamictite, fine-grained silty-sandstone, and diamictite with dropstones; gravel-and sandfills of channels are also important. Elsewhere, the morainal complex is characterized by deltaic sedimentary structures that reflect an interweaving of marine and terrestrial processes. The Búdi morainal complex indicates a recession of the glacier margin, possibly since the Younger Dryas stadial. Sea-level changes, jökulhlaups, and glacier dynamics were responsible for fluctuation of the glacier margin and for the differential rate of calving during the accumulation of the morainal complex. Earlier conclusions on two separated glacier readvances are disputed.