Challenges and progress in drilling offshore buried glacigenic deposits

• Main Authors: Hanebuth, T., Rebesco, Michele, Urgeles, Roger, Lucchi, Renata G., Freudenthal, Tim, CORIBAR Scientific Party
• Format: Conference Object
• Language: unknown
• Published: Istituto Nazionale di Oceanografia e Geofisica Sperimentale 2014
• Subjects: Arctic; Barents Sea; Ice Sheet
• Online Access: http://hdl.handle.net/10261/125308

II Palaeo-Arctic Spatial and Temporal Gateways (PAST Gateways) International Conference and Workshop, 19-23 May 2014, Trieste.-- 1 page High latitudes are a fundamental player in the Earth’s climate system with regard to ice-sheet history and interaction with global ocean circulation. Polar regions are, however, significantly under-investigated and knowledge gaps are significant at and in proximity to the formerly icecovered regions. The physical characteristics of glacial tills and proximal glacigenic marine deposits, with a highly consolidated cohesive matrix, hinder successful sediment coring. Deep penetration of these deposits by conventional piston and gravity coring, commonly used on multi-purpose research vessels, is usually very limited. Drill ships, in contrast, allow for deep drilling but are incomparably expensive. An alternative with penetration depths ≤ 100 m are multi-barrel seafloor drill rigs deployed from conventional research vessels. From mid July to mid-August 2013 a scientific expedition drilled over 40 m long boreholes through tills and glacigenic sediments in the Kveithola Trough (western Barents Sea; drill rig MeBo), that hosted ice-streams during previous glacial times. Bathymetric and sub-bottom depositional structures indicate episodic ice-stream retreat during the climate warming following the last glacial maximum (LGM), resulting in a succession of transversal ridges inside the trough (grounding-zone wedges, GZWs). Despite high stiffness of the glacigenic deposits forming the GZWs and, thus, considerable adhesion on the drill string that implied a reduced sediment recovery, the target base of the GZW was reached. The experience shows that obtaining marine sediment cores and borehole logs in glacially related sediments is technologically challenging. However, the scientific value of drilling into such deposits is worth the effort. The data collected will allow for the very first time to reconstruct the genesis of glacial sediment wedges Peer Reviewed