Deutsches Ozeanographisches
Datenzentrum Inventur der Sonne1-Reise SO236 (DOD-Ref-No.20140030)
Inventory of Sonne1 Cruise SO236 (DOD-Ref-No.20140030)

Working area
Sonne1 SO236 09.08.2014 - 30.08.2014 MALSTROM
Indian Ocean  

Chief Scientist
Port of departure
Port of return
Station map
Betzler Christian Institut fur Geologie der Universitat Hamburg Male Colombo   

Ziel der Reise / Objectives of Cruise:

Cruise 236 of the research vessel SONNE has provided data which are an important building block of the research by members of the Institute for Geology of Hamburg University, aimed to understand the interaction of paleoceanographic and climate change and evolution of the Maldives carbonate platform. The efforts undertaken to reach this goal encompass an earlier cruise with RV METEOR in 2007, a cruise with a smaller boat to analyze atoll anatomy in 2011, and IODP Expedition 359 with RV JOIDES RESOLUTION scheduled for October and November 2015. The specific goal of Cruise SO-236 was to acquire seismic, hydroacoustic, sedimentological, CTD and LISST data as well as current and sediment trap data in the area of the seven sites to be drilled during this expedition. A grid of seismic lines was therefore acquired in the dedicated working areas, which, after the corresponding post-cruise processing, will allow reconstructing the shape of the parts of the carbonate platform which underwent consecutive drowning steps during the Miocene and Pliocene. Seismic surveying was continuously accompanied by hydroacoustic measurements. Due to the bad state of the swath echosounder equipment, multibeam data were very noisy and no backscatter data could be acquired. Nevertheless, a careful and very time-consuming on-board processing of the multibeam data produced useful results with spectacular maps showing drowned banks at the sea floor of the Inner Sea. The new hydroacoustic and seismic data also allowed the discovery of sediment destabilization processes in the Inner Sea, a previously unknown process in the archipelago. Post-cruise research will address the question of the geohazard emanating from this process. Sediment sampling was successful at several localities using gravity and box corer as well as the video grab. Sediment cores will allow to reconstruct sedimentological and microfaunal variations thus providing insights into Holocene and late Pleistocene paleoceanographic and climatic variations. The video grab very successfully recovered rock samples from exposed parts of drowned banks and will allow a dating of the features using large benthic foraminifers. CTD and LISST data provided the first oceanographic data in a west to east transect of the archipelago. Preliminary results show the depth zonation of the water masses at the flanks of the archipelago and in the Inner Sea, and allows to show the occurrence of an oxygen minimum zone which probably corresponds to the eastern expansion of the oxygen minimum zone of the Arabian Sea. During the cruise, two moorings were set out in the Inner Sea. Mooring comprise current meters and sediment traps and will be retrieved after 12 months, i.e. after a full monsoon cycle. All of the strategic goals of the cruise were achieved with great success. A very good database was acquired, which forms a solid fundament for the post cruise analyses and research.

Messungen / Measurements

Typ der Messungen
Type of measurements
Daten im DOD
Data in DOD
IFGEO Betzler Christian 2 stations B73
Sediment traps
. no
IFGEO Betzler Christian 2 stations D01
Current meters
. no
IFGEO Betzler Christian 6 stations G02
. no
IFGEO Betzler Christian 13 stations G03
Core-rock (no. of cores)
. no
IFGEO Betzler Christian 163 tracks G73
Single-beam echosounding
. no
IFGEO Betzler Christian 163 tracks G74
Multi-beam echosounding
. no
IFGEO Betzler Christian 62 tracks G76
Multichannel seismic reflection
. no
GPIHH Betzler Christian 1 n miles G90
Other geological or geophysical measurements
EM120 yes
IFGEO Betzler Christian 13 profiles H10
. no
IFGEO Betzler Christian 1 n miles H80
Other physical measurements
Underway measurements during the whole trip such as coordinates, depth, meteorological parameter and so on yes