Artículo
High resolution images above the Pampean flat slab of Argentina (31-32ºS) from local receiver functions: Implications on regional tectonics
Ammirati, Jean Baptiste
; Perez Lujan, Sofia Beatriz
; Alvarado, Patricia Monica
; Beck, Susan; Rocher, Sebastian
; Zandt, George
Fecha de publicación:
09/2016
Editorial:
Elsevier Science
Revista:
Earth and Planetary Science Letters
ISSN:
0012-821X
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
In the flat slab region of the South Central Andes (∼31–32◦S), geological observations suggest that the regional crustal structure is inherited from the accretion of different terranes during the Ordovician. These structures were later reactivated, first in extension during the Triassic and later in compression during the Andean uplift since the Miocene. Seismological observations confirmed that those fault structures extend to depth with décollement levels that accommodate current crustal shortening in the region. In order to get better insight on the regional tectonics we computed higher frequency receiver functions (RF) from local slab seismicity of intermediate ∼100 km depth. Using a common conversion point (CCP) stacking method we obtained cross sections showing high vertical resolution crustal structure at the transition between the Precordillera and the Frontal Cordillera. In addition we performed a joint inversion of our high frequency RFs with surface wave data from ambient noise tomography allowing us to constrain absolute seismic wave velocities. Our higher resolution images reveal more structural details down to a depth of 80 km and laterally over the flat slab in good agreement with previous studies. Our results help to better identify very shallow discontinuities in seismic velocities. Recent petrological analyses combined with our high-resolution RF structure correlates with a crustal mafic composition and partial eclogitization in the lower crust. We observe a shift in the crustal structure between the Precordillera (east) and the Frontal Cordillera (west). Regional seismicity and previously determined focal mechanisms superimposed over our images indicate this shifting is a thrust structure extending down to a depth of 40 km. Our results suggest the presence of a master fault between the Cuyania (Western Precordillera) and Chilenia (Frontal Cordillera) terranes that probably accommodates the crustal deformation in the Pampean flat slab region since the Late Ordovician.
Palabras clave:
Andean Retroarc
,
Subduction
,
Body Waves
,
Eclogite
,
Surface Waves
,
South America
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Colecciones
Articulos(CIGEOBIO)
Articulos de CENTRO DE INVESTIGACIONES DE LA GEOSFERA Y BIOSFERA
Articulos de CENTRO DE INVESTIGACIONES DE LA GEOSFERA Y BIOSFERA
Articulos(CRILAR)
Articulos de CENTRO REGIONAL DE INV. CIENTIFICAS Y TRANSFERENCIA TECNOLOGICA DE ANILLACO
Articulos de CENTRO REGIONAL DE INV. CIENTIFICAS Y TRANSFERENCIA TECNOLOGICA DE ANILLACO
Articulos(IDEAN)
Articulos de INSTITUTO DE ESTUDIOS ANDINOS "DON PABLO GROEBER"
Articulos de INSTITUTO DE ESTUDIOS ANDINOS "DON PABLO GROEBER"
Articulos(OCA CIUDAD UNIVERSITARIA)
Articulos de OFICINA DE COORDINACION ADMINISTRATIVA CIUDAD UNIVERSITARIA
Articulos de OFICINA DE COORDINACION ADMINISTRATIVA CIUDAD UNIVERSITARIA
Citación
Ammirati, Jean Baptiste; Perez Lujan, Sofia Beatriz; Alvarado, Patricia Monica; Beck, Susan; Rocher, Sebastian; et al.; High resolution images above the Pampean flat slab of Argentina (31-32ºS) from local receiver functions: Implications on regional tectonics; Elsevier Science; Earth and Planetary Science Letters; 450; 9-2016; 29-39
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