Structure and
Sequence
Stratigraphy of an Offshore
Julien, Bailleul1, Chanier Frank1, Gorini Christian1, Mahieux Geoffroy2, Robin Cécile3, Ferriere Jacky1 (1) UMR CNRS 8110 Lille University, Lille, France (2) UMR CNRS 8110 UPJV University, Amiens, France (3) Rennes University, Rennes, France
The initiation and evolution of trench-slope basins on subduction wedges are strongly related to subduction processes. These narrow elongated basins form on
the lower trench slope, their edges consisting of structurally controlled
linear bathymetric highs. In this particular setting, sedimentary processes
may be controlled by both tectonics and sea-level changes. Thus, the study of
the sedimentary record can provide more accurate evaluation of the spatial and
temporal contribution of tectonic activity on the development and stratigraphic evolution of trench-slope basins.
This study is
based on a detailed stratigraphic analysis
of the Titihaoa basin (Hikurangi subduction margin), offshore east coast of
log
(gamma ray and sonic) data, combined with lithostratigraphic
and biostratigraphic data obtained from
well
Titihaoa-1, allows to characterize major unconformities within the sedimentary
infill of the lower trench slope. We interpret most of these unconformities in
terms of
sequence
stratigraphy. On the bases of
comparison with our results with onshore analogues, we propose a stratigraphic and structural conceptual model for
trench-slope basin development taking into account 1) our geophysical study of
the Titihaoa basin which permits to precise the role
of deformation processes on the basin geometry and on
sequence
development and organisation, and 2) the
analysis
of the onshore Akitio basin which provides accurate descriptions and
interpretations of turbidites facies
and related deep-sea deposits with a focus on the evolution of sedimentary
systems in response to changes in style and/or amplitude of tectonic activity.