Publication: Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)
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Publication Date
2009
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Elsevier
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Abstract
Multibeam bathymetry data acquired during the 2005 Spanish R/V Hespérides cruise and reprocessed
multichannel seismic profiles provide the basis for the analysis of the morphology and deformation in the
central Muertos Trough and Muertos thrust belt. The Muertos Trough is an elongated basin developed where
the Venezuelan Basin crust is thrusted under the Muertos fold-and-thrust belt. Structural variations along the
Muertos Trough are suggested to be a consequence of the overburden of the asymmetrical thrust belt and by
the variable nature of the Venezuelan Basin crust along the margin. The insular slope can be divided into
three east–west trending slope provinces with high lateral variability which correspond to different accretion
stages: 1) The lower slope is composed of an active sequence of imbricate thrust slices and closed fold axes,
which form short and narrow accretionary ridges and elongated slope basins; 2) The middle slope shows a
less active imbricate structure resulting in lower superficial deformation and bigger slope basins; 3) The
upper slope comprises the talus region and extended terraces burying an island arc basement and an inactive
imbricate structure. The talus region is characterized by a dense drainage network that transports turbidite
flows from the islands and their surrounding carbonate platform areas to the slope basins and sometimes to
the trough. In the survey area the accommodation of the ongoing east–west differential motion between the
Hispaniola and the Puerto Rico–Virgin Islands blocks takes place by means of diffuse deformation. The asymmetrical development of the thrust belt is not related to the geological conditions in the foreland, but rather may be caused by variations in the geometry and movement of the backstop. The map-view curves of the thrust belt and the symmetry of the recesses suggest a main north–south convergence along the Muertos margin. The western end of the Investigator Fault Zone comprises a broad band of active normal faults which result in high instability of the upper insular slope.