AMS criteria for determining the azimuth and dip of a subduction zone from a mafic dyke swarm

J. P. Lefort, T. Aïfa, F. Hervé

Resultado de la investigación: Conference contribution

4 Citas (Scopus)

Resumen

Study of a Miocene dyke swarm located in Southern Patagonia (Chile) shows that the simultaneous opening of the dykes arises many theoretical difficulties. However, if we consider at the same time the general structural pattern and the macroscopic and AMS (anisotropy of magnetic susceptibility) evidence for dextral or sinistral transtensions in many dykes, a general kinematic model based on a physical indentation experiment can be proposed. We postulate that a dramatic acceleration of the subduction at the time of formation of all these structures acted like a large indenter. The direction of extension which prevailed during this acceleration and which corresponds to the orientation of the feldspars or the magnetic tiling can be used to restore the original azimuth of the oceanic convergence. Study of the corrected degree of anisotropy (P′) across each dyke shows that most of the dykes display a higher value close to their Andean edge. We also observed that the location of the highest P′ value does not depend on the sense of the transtensional opening. P′ can be thus used to decipher the sense of dip of an old subduction.

Idioma originalEnglish
Título de la publicación alojadaDyke Swarms - Time Markers of Crustal Evolution - Proceedings of the 5th International Conference, IDC-5
Páginas49-62
Número de páginas14
EstadoPublished - 2006
Evento5th International Dyke Conference: Dyke Swarms - Time Markers of Crustal Evolution, IDC-5 - Rovaniemi, Finland
Duración: 31 jul 20053 ago 2005

Other

Other5th International Dyke Conference: Dyke Swarms - Time Markers of Crustal Evolution, IDC-5
PaísFinland
CiudadRovaniemi
Período31/07/053/08/05

Huella dactilar

magnetic anisotropy
dike swarm
Magnetic susceptibility
azimuth
subduction zone
dip
Anisotropy
subduction
transtension
indentation
Indentation
dike
Kinematics
anisotropy
kinematics
Miocene
experiment
Experiments
Direction compound

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geotechnical Engineering and Engineering Geology

Citar esto

Lefort, J. P., Aïfa, T., & Hervé, F. (2006). AMS criteria for determining the azimuth and dip of a subduction zone from a mafic dyke swarm. En Dyke Swarms - Time Markers of Crustal Evolution - Proceedings of the 5th International Conference, IDC-5 (pp. 49-62)
Lefort, J. P. ; Aïfa, T. ; Hervé, F. / AMS criteria for determining the azimuth and dip of a subduction zone from a mafic dyke swarm. Dyke Swarms - Time Markers of Crustal Evolution - Proceedings of the 5th International Conference, IDC-5. 2006. pp. 49-62
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Lefort, JP, Aïfa, T & Hervé, F 2006, AMS criteria for determining the azimuth and dip of a subduction zone from a mafic dyke swarm. En Dyke Swarms - Time Markers of Crustal Evolution - Proceedings of the 5th International Conference, IDC-5. pp. 49-62, 5th International Dyke Conference: Dyke Swarms - Time Markers of Crustal Evolution, IDC-5, Rovaniemi, Finland, 31/07/05.

AMS criteria for determining the azimuth and dip of a subduction zone from a mafic dyke swarm. / Lefort, J. P.; Aïfa, T.; Hervé, F.

Dyke Swarms - Time Markers of Crustal Evolution - Proceedings of the 5th International Conference, IDC-5. 2006. p. 49-62.

Resultado de la investigación: Conference contribution

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N2 - Study of a Miocene dyke swarm located in Southern Patagonia (Chile) shows that the simultaneous opening of the dykes arises many theoretical difficulties. However, if we consider at the same time the general structural pattern and the macroscopic and AMS (anisotropy of magnetic susceptibility) evidence for dextral or sinistral transtensions in many dykes, a general kinematic model based on a physical indentation experiment can be proposed. We postulate that a dramatic acceleration of the subduction at the time of formation of all these structures acted like a large indenter. The direction of extension which prevailed during this acceleration and which corresponds to the orientation of the feldspars or the magnetic tiling can be used to restore the original azimuth of the oceanic convergence. Study of the corrected degree of anisotropy (P′) across each dyke shows that most of the dykes display a higher value close to their Andean edge. We also observed that the location of the highest P′ value does not depend on the sense of the transtensional opening. P′ can be thus used to decipher the sense of dip of an old subduction.

AB - Study of a Miocene dyke swarm located in Southern Patagonia (Chile) shows that the simultaneous opening of the dykes arises many theoretical difficulties. However, if we consider at the same time the general structural pattern and the macroscopic and AMS (anisotropy of magnetic susceptibility) evidence for dextral or sinistral transtensions in many dykes, a general kinematic model based on a physical indentation experiment can be proposed. We postulate that a dramatic acceleration of the subduction at the time of formation of all these structures acted like a large indenter. The direction of extension which prevailed during this acceleration and which corresponds to the orientation of the feldspars or the magnetic tiling can be used to restore the original azimuth of the oceanic convergence. Study of the corrected degree of anisotropy (P′) across each dyke shows that most of the dykes display a higher value close to their Andean edge. We also observed that the location of the highest P′ value does not depend on the sense of the transtensional opening. P′ can be thus used to decipher the sense of dip of an old subduction.

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Lefort JP, Aïfa T, Hervé F. AMS criteria for determining the azimuth and dip of a subduction zone from a mafic dyke swarm. En Dyke Swarms - Time Markers of Crustal Evolution - Proceedings of the 5th International Conference, IDC-5. 2006. p. 49-62