Bialas, Jörg, Klaucke, Ingo and Haeckel, Matthias, eds. (2014) FS MARIA S. MERIAN Fahrtbericht / Cruise Report MSM34/1 & 2 - SUGAR Site ; Varna – Varna, 06.12.13 – 16.01.14. . GEOMAR Report, N. Ser. 015 . GEOMAR Helmholtz-Zentrum für Ozeanforschung, Kiel, Germany, 111 pp. DOI 10.3289/GEOMAR_REP_NS_15_2014.

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Abstract

During the two legs of cruise MSM34 of R/V MARIA S. MERIAN regional 2D seismic
surveying, high resolution 2D and 3D seismic imaging, geo-chemical sampling, heatflow
measurements and long-term piezometer installations were undertaken.
A grid of 28 2D seismic profiles was collected across the palaeo Danube delta. A number
of inactive and partly buried channel systems could be mapped. Most of them were underlain
by one or more bottom simulation reflectors (BSR). Based on the seismic brute stack images
and the limits of the MeBo drilling device a prospective channel system with indications for
possible gas hydrate formation at shallow depth (BSR, inverted strong amplitudes) could be
identified in about 1500 m water depth. High resolution 2D seismic and 3D P-Cable seismic
were used together with OBS deployments in order to allow structural mapping and physical
description of the channel infill. Heatflow measurements and geochemical analyses of gravity
and multi corer samples accompany these investigations. Neither the multibeam water column
images nor Parasound records show any evidence of flares (gas bubbles in the water column)
in this working area suggesting a well sealed hydrate reservoir.
Active gas expulsion from the seafloor was observed at about 200 m water depth circling
around a slump area. The base plane of the failed sediment volume builds the current seafloor
at about 600 m to 700 m water depth. On regional 2D seismic profiles a BSR has been
mapped underneath the slope failure with unexpectedly strong upward bending. High
resolution 2D and 3D P-Cable seismic investigations with complementary OBS deployment
will allow imaging the BSR outline. Moreover velocity analyses, heatflow measurements and
geo-chemical samples will be available for a detailed description of hydrate distribution and
sediment parameters.
In a third working area high resolution 2D seismic reflection profiles were acquired across
a fully buried channel system. Together with the regional seismic lines slope failure of the
channel fill material can be studied across the slope extension of the system.

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