Tectonic implications of tomographic images of subducted lithosphere beneath Northwestern South America
- Leeds Univ. (United Kingdom)
- Univ. of Texas, Austin (United States)
Tomographic images and deep seismicity of the mantle beneath northwestern South America support the existence of extensive and continuous subducted slabs which may be important controls on the neotectonic deformation of the overriding South America plate. Using tomographic data, we have estimated lateral continuity, regional dip, downdip length and approximate convergence direction of two, largely aseismic slabs. Tomographic data suggests that the Cauca slab, previously defined using earthquakes beneath southern Colombia, extends 300 km into the mantle beneath northern Colombia, has an average dip of 50[degrees], and is the downdip extension of Eocene to Miocene Panama island arc and Oligocene-Miocene oceanic crust of the Nazca plate. The Maracaibo slab of northern Colombia and western Venezuela extends up to 450 km into the mantle at an average angle of 16[degrees] and is the downdip extension of Late Cretaceous oceanic plateau crust of the Caribbean Sea. The boundary between the two slabs is less than 50 km in width. The Maracaibo and northern Cauca slabs are generally aseismic and not associated with an overlying volcanic arc. Instead, both slabs are overlain by broad zones of diffuse active faulting and topography in the northern Andes. The shallow dip, angle of oblique subduction and thickness of the Maracaibo slab may produce crustal deformation including northward tectonic escape of the Maracaibo block, a triangular wedge of continental crust in the overriding South America plate.
- OSTI ID:
- 6105419
- Report Number(s):
- CONF-930306--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:2; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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58 GEOSCIENCES
580000 -- Geosciences
ANDES
ATLANTIC OCEAN
CARIBBEAN SEA
CENTRAL AMERICA
COLOMBIA
CONTINENTAL CRUST
DEFORMATION
DEVELOPING COUNTRIES
EARTH CRUST
EARTH MANTLE
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
LATIN AMERICA
MOUNTAINS
OCEANIC CRUST
PANAMA
PLATE TECTONICS
SEAS
SEISMICITY
SLABS
SOUTH AMERICA
SUBDUCTION ZONES
SURFACE WATERS
TECTONICS
TOPOGRAPHY
VENEZUELA