The MeBo drilling program and stations on land

But never in the past has there been any drilling in this region, which is why we are always anxious if the drilling is successful and what the core will reveal. How deep can the drill bit penetrate the subsurface below the seafloor? How much sediment core can be recovered in the drill barrels? What is the cored sediment material made of? And of particular importance is the question of how long a drill operation can last before is has to be stopped due to approaching icebergs, large ice floes, a technical problem, or an unexpected early wearing of the drill bit?

Two groups have been busy in the last 10 days using helicopter transport almost daily to fly to the mainland or small islands of Pine Island Bay. The research project of geodesists Mirko Scheinert and Benjamin Ebermann of TU Dresden comprises precise GPS measurements at selected sites on outcropping rock. Highly accurate point coordinates – with an accuracy of 2-4 mm horizontally and 5-7 mm vertically – are measured over several days. By comparing data collected over many years, they can measure differences in the position coordinates and derive temporal changes and deformations from these. The vertical deformation is in particular important as this provides indications on how much the Earth’s crust is uplifted due to the glacial isostatic adjustment (GIA). This GIA effect can be explained by linking past and present ice mass changes with the rheology (material property) of the Earth’s crust and mantle. In our work region, we measured GPS records on point coordinates on Mt. Manthe and on an island north of Pine Island Glacier. These were repeat measurements from earlier measurements conducted in 2006 and 2010. Additional coordinate points were marked and first-time measured, e.g. on the northernmost of the Backer Islands and on Clark Island. We hope that the GPS instrument on Clark Island will continue functioning a while, because the present program of Polarstern will allow us to return to this island for instrument de-installation.

The second group of geologists Max Zundel (University of Bremen) and Yani Najman (Lancaster University, UK) have also used the good weather conditions to land on many of the island in Pine Island Bay. They sample crystalline basement rocks and erratic blocks, which are rocks transported large distances to the islands by movement of glaciers. By age dating of basement rock samples, they can derive the regional cooling history of the rocks, which is an indication of erosion, sedimentation and uplift of this region of the last 100 million years. This information is used to reconstruct the long-term surface development, providing important clues on the beginning and the behaviour of the West Antarctica glaciation. The erratic blocks are age-dated to reveal the time when these rocks, and therefore the islands, were uncovered from ice. This will help to reconstruct the ice sheet retreat in Pine Island Bay for the last 15,000 years.

We all feel that the days are flying by quickly, also because of the permanent re-planning of our research activities. Yesterday was middle time of the expedition, which we celebrated with a traditional ‘Bergfest’. A fantastic BBQ was set on deck by the excellent kitchen team.

The daily arriving satellite images of the German Aerospace Center (DLR) have indicated it already: A large ice-floe field has been drifting into our work area by constant easterly winds. We had to stopped our drilling here and set course to a previously little investigated part of the embayment east of Burke Island. There we will go for another drill target with a different objective …

All are well and send their best regards and wishes

Mirko Scheinert, Max Zundel and Karsten Gohl