Volcano-tectonic evolution of the Santa Maria Island (Azores) : implications for paleo-stress evolution at the western Eurasia-Nubia plate boudnary - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Volcanology and Geothermal Research Année : 2015

Volcano-tectonic evolution of the Santa Maria Island (Azores) : implications for paleo-stress evolution at the western Eurasia-Nubia plate boudnary

A.L.R. Sibrant
  • Fonction : Auteur
  • PersonId : 926850
A. Hildenbrand
F.O. Marques
  • Fonction : Auteur
  • PersonId : 926849

Résumé

The growth and decay of oceanic volcanoes developed close to plate boundaries are intrinsically related to a competition between construction and destruction processes, partly controlled by tectonic strain and stresses. From morphologic, stratigraphic, tectonic and new high-precision K-Ar data, we present a comprehensive picture of the volcano-tectonic evolution of Santa Maria, and discuss its significance regarding the stress evolution and regional deformation in the Azores. Our new data show that: (1) the western flat portion of the island is mostly composed of west-dipping volcanic rocks here dated between 5.70 ± 0.08 and 5.33 ± 0.08 Ma, which we consider the remnants of an Older Shield Volcano; (2) more than half of this early volcanic complex has been removed by an east-directed large-scale sector collapse; (3) a second volcano, here coined the Younger Shield Volcano, grew rapidly on the collapse scar between at least 4.32 ± 0.06 and 3.94 ± 0.06 Ma; (4) more than half of this new volcano was removed by a second large-scale sector collapse most probably around 3.6 Ma, based on the ages of parasitic scoria cones sitting unconformably on the Younger Shield Volcano; (5) the latest parasitic volcanic activity is here dated at 2.84 ± 0.04 Ma, extending significantly the known eruptive history of Santa Maria. Morpho-structural data (shape of the island, faults, dikes, and distribution of volcanic cones) show a significant control of construction and destruction along the N045° and N150° directions. The age of the lavas intruded by dikes suggests that the N045° and the N150° trends are ca. 5.3 Ma old and younger than ca. 4.3 Ma, respectively. Based on the new data, we conclude that a change in the regional stress field occurred between 5.3 and 4.3 Ma, most likely associated with a major reconfiguration of the Eurasia/Nubia plate boundary in the Azores.
Fichier non déposé

Dates et versions

hal-01099976 , version 1 (05-01-2015)

Identifiants

  • HAL Id : hal-01099976 , version 1

Citer

A.L.R. Sibrant, A. Hildenbrand, F.O. Marques, A.C. Goulart da Costa. Volcano-tectonic evolution of the Santa Maria Island (Azores) : implications for paleo-stress evolution at the western Eurasia-Nubia plate boudnary. Journal of Volcanology and Geothermal Research, 2015, pp.doi:10.1016/j.jvolgeores.2014.12.017 (IF 2,515). ⟨hal-01099976⟩
37 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More