Open AccessPast forearc deformation in Nicaragua and coupling at the megathrust interface: Evidence for subduction retreat?
Author(s) -
Cailleau B.,
Oncken O.
Publication year - 2008
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2007gc001754
Subject(s) - forearc , geology , subduction , seismology , slab , volcanic arc , trench , fault (geology) , tectonics , paleontology , chemistry , organic chemistry , layer (electronics)
Deformation at the boundary between the Cocos and Caribbean plates in Nicaragua is currently focused in the volcanic arc in the form of arc‐parallel shearing. In the middle Miocene, however, there was widespread subsidence with local uplift in the outer‐forearc and inner‐forearc broad uplift. To understand this complex deformation, we use numerical modeling to investigate the effect of inhomogeneous friction at the megathrust fault on strain localization in the upper plate. A good fit is obtained when (1) the interface between the slab and upper plate is not situated at the current Wadati‐Benioff zone but rather is moved 50 km landward to where subduction may have been active in the early Tertiary and (2) there is high stress accumulation between 15 and 25 km depths and low stress accumulation updip and downdip of the thrust interface. The results are consistent with a high‐velocity block being the remnant of an oceanic plateau that subducted in the Eocene and was later incorporated into the upper plate. We suggest that this geometry persisted into the middle Miocene, before the slab broke off and the thrust interface jumped seaward.