MSM87 IODP NW-Africa
Summary - MSM87 November 17th to November 25th, 2019 Las Palmas (Canary Islands, Spain) - Mindelo (Cape Verde)
A seismic pre-site survey for an International Ocean Discovery Program (IODP) was conducted on Maria S. Merian research cruise MSM87 in order to find a potential drill-site on the Cape Verde Plateau offshore NW Africa.
The IODP pre-proposal ‘Neogene Climate of NW Africa’ suggests investigating: i) NW Af-rican climate in a warmer world, and ii) High productivity ecosystem response to climates different from today.Sediment cores should be retrieved at five locationsoff NW-Africa. more A central site is proposed on the Cape Verde Plateau close to ODP Site 659but no modern high-resolution seismic data are available for this area. The main goal of Cruise MSM87is to carry out a seismic pre-site sur-vey for an IODP site on the Cape Verde Plat-eau. The survey aims in identifying a site where the Plio-Pleistocene is thinner and the Miocene is thicker than at Site 659. This would allow to APC-XCB deeper into the Mi-ocene, which is crucial for retrieving high-quality cores for paleoclimate investigations.
Hydroacoustic data collection started at 02:40h on November 17 after leaving the Spanish EEZ. A short survey at the headwall area of the Sahara Slide was carried out in the afternoon of the same day. The data were collected to complement the site survey data for two proposed IODP-sites in this area. We also collected some additional data of a landslide scar located slightly south of the Sahara Slide. The transit was continued on November 18. It was interrupted for a short test of the seismic equipment in the afternoon.
The test revealed problems with one streamer section and a trigger box. Both problems could be quickly solved following the test. We reached the northern boundary of the Cape Verde Plateau on November 19 at 08:00h local time. Deployment of the seismic equipment was very smooth. The initial profiles crossed the Cape Verde Plateau from North to South. This set of profiles included crossings of a proposed IODP site at the northern part of the plateau and the old ODP Site 659. The data show relatively homogeneous sediment patterns with a slight thickness decrease of the Plio/Pleistocene sediments to the north. We crossed DSDP-Site 368 around noon on November 20. November 21 was used for a acquiring a long line at the western edge of the Cape Verde Plateau, where the GEBCO bathymetry shows a few embayments of the 3200 m contour, which may indicate erosional processes. The line showed only small variations of the Plio/Pleistocene sediment thickness.
A cross line for a potential site identified on the first seismic line north of the plateau was collected in the evening the same day. This was followed by a long line on the eastern site of the plateau in the night November 21/22. The survey was interrupted for short period in the morning of November 22 due to a leakage of the airgun. This problem was fixed very quickly. The data analysis revealed relatively homogenous sediment patterns for most parts of the surveys but significant variations with a potential thinning ofthe Plio/Pleistocene sediments were identified south of ODP-Site 659. A detailed survey of this area was carried out from noon November 22 and continued until the evening of November 23. These data show some significant thinning of the near surface sedimentary successions and we are optimistic to locate promising drill sites along these seismic lines. On our way to the west, we collected another line across the ODP site 659 and a potential new site on the eastern edge of the Cape Verde Plateau. The seismic gear was retrieved on November 24 at 08:00h. Hydroacoustic imaging was continued until 18:00h the same day during the transit to Mindelo. We arrived in the port of Mindelo on November 25 at 08:30h. RV MARIA S. MERIAN-Cruise MSM87 was a great success. Hydroacoustic data were collected along the entire cruise. Continuous seismic data acquisition at the Cape Verde Plateau over 5 days resulted in 1000 km of high-quality high-resolution seismic data. The data will allow to collected promising sites for drilling in the frame of the International Ocean Discovery Program. In addition, the data can be used to investigate the sedimentary architecture of the Cape Verde Plateau.
Contact persons: Prof. Dr. Sebastian Krastel,
Teilnehmer:
- Rachel Barrett
- Felix Gross
- N. Gross
- Heiko Jähmlich
- Sven Heinrich
- Phillipp Held
- Kristopf König
- Elodie Lebas
- Kai-Frederik Lenz
- Ralph Schneider (KMS)
- Jens Schneider v. Deimling
- Henriette Wilckens