A sedimentological study of glacial deposits in the upper Sjællandselv area, Jameson Land, East Greenland

• Main Author: Andersson, Torbjörn
• Format: Other/Unknown Material
• Language: English
• Published: Lunds universitet/Geologiska institutionen 1994
• Subjects: geography; geology; sedimentology; glacial deposit; Sjællandselv area; Jameson Land; Greenland; Earth and Environmental Sciences; Eastern Hill; Jyllandselv; Western Hill; East Greenland; North Atlantic
• Online Access: http://lup.lub.lu.se/student-papers/record/2370090

Summary: The fieldwork preceding this Master degree thesis took place in Jameson Land, East Greeniand, within the frame of the PONAM (Polar North Atlantic Margins; Late Cenozoic evolution) project. In central Jameson Land, a plateau area at approximately 500 m.a.s.l. forms a marked height in the area around the uppermost reaches of Jyllandselv. Ac. 2 km wide valley, where river ravines are cut down more than 100 m into the Jurassic bedrock, divides the plateau into a northern and a southern part. The investigated area is located in the southern part of the plateau area, between the two deep river valleys of upper Sjællandselv and upper Jyllandselv, where two elongated hills with top surfaces at approximately 510 m.a.s.l. form a 5 km long till covered complex. The eastern hill has gentle slopes, whereas the western hill has terraced slopes on the northern, eastern and southern sides. Seven sites have been investigated through detailed sedimentological logging of excavated sections and four lithostratigraphic units, A-D, have been distinguished. Unit A shows fine sand and coarse silt sediments dominated by type A and type B ripple cross-lamination and planar parallel-lamination. These sediments are interpreted to be formed by rapid deposition from turbidity currents along a prodelta slope or at the distal parts of a subaqueous fan. Palaeocurrents show a dispersed pattern towards the south, south-east, east, north-east and the north. Unit B consists of a diamicton with a coarse to medium sand matrix and boulders up to 1 m in diameter occur. The diamicton is interpreted to be a till. It covers the two elongated hills and lies on top of unit A. A fabric analysis shows an ice-movement towards the south-east. Unit C comprises sandy fluvial bedforms. Trough cross-lamination formed by the migration of 3-D dunes is the most common lithofacies and is interpreted as in channel deposition of a sandy braided river. Palaeocurrents are opposed to the present drainage system. Unit D is a diamicton with a high silt and clay ...