Volatile und Fluide in Subduktionszonen

Overview Theme B2

The subproject B2 is concerned with the dynamic forces driving mud diapirism. For the second phase of the SFB 574 it will broaden its focus to include mass wasting processes on the Middle America continental margin.

As a result of the initial phase of the SFB574 it is known that mud diapirism on the Costa Rica erosive continental margin is an important mechanism in dewatering the forearc region that influences the overall fluid and volatile budget of this subduction zone. We will continue to describe the nature and internal dynamics of mounds and extend our working area towards the northern part of the Middle America margin to develop a better regional understanding of mud diapir distribution and identify links between mound type and subduction mechanics.

Fig. B2-1:Bathymetric overview of the Costa Rica continental margin showing the location of BGR and GEOMAR slides (rectangle).

Geophysical characterization of mud diapirs, originally carried out within subproject B1, will be continued using high resolution surface seismics, Parasound, and imaging with the deep-tow streamer system. Mapping of the lateral extent of the BSR in the vicinity of mud diapirs, seismic stratigraphy and velocity structure beneath the mounds will help identifying the source region and eruption dynamics of mud diapirs.

Characteristics of shallow mass wasting features near the upper limit of the local gas hydrate stability field off Costa Rica suggest that these are directly related to hydrate dissociation. Through sampling for geotechnical and sedimentological work and the development of in situ observation tools we will characterize the boundary conditions of slope stability off Costa Rica.