Chronology and styles of glaciation in an inter-fjord setting, northwestern Svalbard
Jon Y. Landvik
Heidi T. Ryen
Summary, in English
A 30-m-thick sedimentary succession at Leinstranda on the southwestern coast of Br circle divide ggerhalv circle divide ya, northwestern Svalbard, spans the two last glacial-interglacial cycles and reveals information on glacial dynamics, sea-level changes and the timing of these events. We investigated the deposits using standard stratigraphical and sedimentological techniques, together with ground-penetrating radar, and established an absolute chronology based mainly on optically stimulated luminescence dating. We identified facies associations that represent depositional settings related to advancing, overriding and retreating glaciers, marine and littoral conditions and periglacial surfaces. The environmental changes show an approximate cyclicity and reflect glaciations followed by high sea levels and later regression. The luminescence chronology places sea-level highstands at 185 +/- 8 ka, 129 +/- 10 ka, 99 +/- 8 ka and 36 +/- 3 ka. These ages constrain the timing of recorded glaciations at Leinstranda to prior to c. 190 ka, between c. 170 and c. 140 ka (Late Saalian) and between c. 120 ka and c. 110 ka (Early Weichselian). The glaciations include phases with glaciers from three different source areas. There is no positive evidence for either Middle or Late Weichselian glaciations covering the site, but there are hiatuses at those stratigraphic levels. A high bedrock ridge separates Leinstranda from the palaeo-ice stream in Kongsfjorden, and the deposits at Leinstranda reflect ice-dynamic conditions related to ice-sheet evolution in an inter-fjord area. The environmental information and the absolute chronology derived from our data allow for an improved correlation with the marine record, and for inferences to be made about the interaction between land, ocean and ice during the last glacial-interglacial cycles.