ALBERT

Description: The MARUM-MeBo (abbreviation for Meeresboden-Bohrgerät, the German expression for seafloor drill rig) is a robotic drilling system that is developed since 2004 at the MARUM Center for Marine Environmental Sciences at the University of Bremen in close cooperation with Bauer Maschinen GmbH and other industry partners. The MARUM-MeBo drill rigs can be deployed from multipurpose research vessel like, RV MARIA S. MERIAN, RV METEOR, RV SONNE and RV POLARSTERN and are used for getting long cores both in soft sediments as well as hard rocks in the deep sea. The first generation drill rig, the MARUM-MeBo70 is dedicated for drilling depths of more than 70 m (Freudenthal and Wefer, 2013). Between 2005 and 2017 it was deployed on 18 research expeditions and drilled more than. 3 km into different types of lithologies including carbonate and crystalline rocks, gas hydrates, sands and gravel, glacial till and hemipelagic mud with an average recovery rate of 67 %. In February and March 2017 the MeBo70 was used on the West Antarctic continental shelf in the Amundsen Sea Embayment for the first time. The goal of the deployment on RV Polarstern expedition PS104 was to recover a series of sediment cores from different ages that will provide material for investigating the glaciation history of this area known as the most dynamic drainage area of the West Antarctic Ice Sheet. In this presentation we will focus on the operational experiences of this first deployment of a multi-barrel sea floor drill rig on the Antarctic continental shelf. References: Freudenthal, T and Wefer, G (2013) Drilling cores on the sea floor with the remote-controlled sea floor drilling rig MeBo. Geoscientific Instrumentation, Methods and Data Systems, 2(2). 329-337. doi:10.5194/gi-2-329-2013

Description: The main purpose of cruise JR298 was to collect marine geological and geophysical samples and data to support International Ocean Discovery Program (IODP) proposal 732- Full2, “Sediment drifts off the Antarctic Peninsula and West Antarctica” (Channell, Larter, Hillenbrand et al.). The ship time was allocated for this purpose on the basis of a Site Survey Investigation grant from the NERC UK-IODP Programme (NE/J006548/1: Depositional patterns and records in sediment drifts off the Antarctic Peninsula and West Antarctica) to R.D. Larter, C.-D. Hillenbrand (both BAS), D.A. Hodell (University of Cambridge) and A.G.C. Graham (University of Exeter). The data and samples collected will also be used in two Collaborative Gearing Scheme projects, an Antarctic Science Bursary project, a University of Cambridge PhD studentship, and within the National Capability remit of the BAS Science Teams in “Geology and Geophysics” and “Palaeoenvironments and Climate Change”. These projects are: • Tracing and reconstructing the neodymium and carbon isotopic composition of circum-Antarctic waters (CGS-100, PI: A.M. Piotrowski, Department of Earth Sciences, University of Cambridge; cruise participants: A.M. Piotrowski and T.J. Williams). • Structural characterisation of Late Quaternary sediments from West Antarctic contourite drifts using three dimensional X-ray imaging (CT-scanning) (CGS-98, PI: C. Ó Cofaigh, Department of Geography, Durham University; cruise participant: J. Horrocks) • Tracing the Quaternary evolution of the Antarctic Peninsula and West Antarctic Ice Sheets using lead isotopes in ice-rafted feldspar mineral grains (Antarctic Science Bursary awarded to C. Cook). • Seismic imaging of oceanographic structures and processes in the Southern Ocean south of the Polar Front (component of University of Cambridge/BP Institute PhD studentship; primary supervisor: N.J. White, Department of Earth Sciences, University of Cambridge; PhD student and cruise participant: K.L. Gunn). • Modelling crustal structure across the Bellingshausen Gravity Anomaly and oceanic fracture zones formed at the Antarctic-Phoenix Ridge through integration of marine potential field and seismic data (Collaboration between two BAS Science Teams; cruise participant: T.A.R.M. Jordan). 2 The cruise also provided support for physical oceanography projects by deploying six Argo floats and rescuing a malfunctioning sea glider. Towards the end of the cruise, RRS James Clark Ross was diverted to Rothera to uplift 16 personnel who had been flown across from Halley in two ALCI Basler aircraft because the sea ice situation in the Weddell Sea was considered to pose a significant risk to the scheduled last call of the season at Halley by RRS Ernest Shackleton. This uplift resulted in a two-day delay to arrival at Punta Arenas at the end of the cruise, which was in addition to a two-day extension already agreed as a result of departure from Punta Arenas having been delayed by slow refuelling. Adverse weather conditions, particularly during the first half of the cruise, resulted in more downtime than the amount of contingency time that had been allowed in the proposal. As a result, one less piston core and about 20% fewer line-km of seismic data were collected than had been planned. Nevertheless, the key objectives were achieved and the cores and data that were collected are of very good quality. The data and cores collected on cruise JR298, combined with existing data and cores, should satisfy all of the requirements of the Site Characterisation Panel and the Environmental Protection and Safety Panel of IODP. They will also provide a good basis for addressing the science objectives set out in the UK-IODP Site Survey Investigation proposal and those of the ancillary projects listed above.