Palaeomagnetic study of a subaerial volcanic ridge (Sao Jorge Island, Azores) for the past 1.3 Myr: evidence for the CobbMountain Subchron, volcano flank instability and tectonomagmatic implications

We present a palaeomagnetic study on 38 lava flows and 20 dykes encompassing the past 1.3 Myr on S. Jorge Island (Azores Archipelago—North Atlantic Ocean). The sections sampled in the southeastern and central/western parts of the island record reversed and normal polarities, respectively. They indic...

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Bibliographic Details
Published in:Geophysical Journal International
Main Authors: Silva, P. F., Henry, B., Marques, F. O., Hildenbrand, A., Madureira, P., Mériaux, C. A., Kratinová, Z. (Zuzana)
Format: Article in Journal/Newspaper
Language:English
Published: 2012
Subjects:
palaeomagnetic secular variation
magnetostratigraphy
rock and mineral magnetism
Atlantic Ocean
Jorge Island
Tilting
North Atlantic
Online Access:https://doi.org/10.1111/j.1365-246X.2011.05320.x
http://hdl.handle.net/11104/0212140
Description
Summary:We present a palaeomagnetic study on 38 lava flows and 20 dykes encompassing the past 1.3 Myr on S. Jorge Island (Azores Archipelago—North Atlantic Ocean). The sections sampled in the southeastern and central/western parts of the island record reversed and normal polarities, respectively. They indicate a mean palaeomagnetic pole with a latitude shallower than that expected from Geocentric Axial Dipole assumption, suggesting an effect of non-dipolar components of the Earth magnetic field. Virtual Geomagnetic Poles of eight flows and two dykes closely follow the contemporaneous records of the Cobb Mountain Subchron (ODP/DSDP programs) and constrain the age transition from reversed to normal polarity. Volcano flank instabilities, probably related to dyke emplacement along an NNW–SSE direction, led to southwestward tilting of the lava pile towards the sea.

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