Paleomagnetism of the Mid-Tertiary Ayacara Formation, southern Chile: Counterclockwise rotation in a dextral shear zone

C. Rojas, M. E. Beck, R. F. Burmester, J. Cembrano, F. Hervé

Resultado de la investigación: Contribución a una revistaArtículo

28 Citas (Scopus)

Resumen

Relative motions of the southern Chilean forearc are assessed through a paleomagnetic study of teh Eocene-Miocene Ayacara Formation. This marine volcaniclastic unit was studied at three localities, all immediately west of the Liquiñe-Ofqui fault zone (LOFZ), a 1000-km-long, NS-trending intracontinental shear zone with probable Cenozoic right-lateral displacement. A paleomagnetic pole (74.8S; 44.0E; A-95, 8.5°) was calculated by combining 11 site-mean VGP from the Ayacara Fm. with three sites from the nearby Oligocene Cocotue Beach basalts (previously published). When compared with a 20-40 Ma North American cratonic pole rotated into the South American reference framework this pole implies counterclockwise rotation of 14.6±11.8. We speculate that this counterclockwise rotation results from processes that tend to impel a detached sliver of continental crust northward along the continental margin, against a buttress. In our model, northward displacement of the trailing edge of the sliver is accomplished by segmenting the sliver into lens-shaped blocks which rotate counterclockwise as they move northward. The geometry of the LOFZ clearly supports this model, which may have application to other buttressed strike-slip fault zones.

Idioma originalInglés
Páginas (desde-hasta)45-56
Número de páginas12
PublicaciónJournal of South American Earth Sciences
Volumen7
N.º1
DOI
EstadoPublicada - 1 ene 1994

Áreas temáticas de ASJC Scopus

  • Geología
  • Procesos de la superficie terrestre

Huella Profundice en los temas de investigación de 'Paleomagnetism of the Mid-Tertiary Ayacara Formation, southern Chile: Counterclockwise rotation in a dextral shear zone'. En conjunto forman una huella única.

  • Citar esto