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Rift‐zone development around a plume‐related magma centre on the Isle of Skye (Scotland): a model for stress inversions
Author(s) -
Doubre Cécile,
Geoffroy Laurent
Publication year - 2003
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.2003.00494.x
Subject(s) - geology , rift , magma chamber , magma , stress field , petrology , volcano , rift zone , intrusion , lava , basalt , gabbro , seismology , geochemistry , finite element method , tectonics , physics , thermodynamics
Using the example of the Isle of Skye in Scotland, we investigate the influence of pressure variations in upper‐crustal magma reservoirs on the development of rift‐type normal faulting around central volcanoes. The regional synmagmatic stress regime is of strike‐slip type in Scotland during the Lower Tertiary. During a prolonged period of overall high pressure in the Skye magma reservoir (gabbro intrusion stage), crustal extension results from the injection of basaltic dykes parallel to the trend of the far‐field maximum stress. During a subsequent period of pressure decrease in the reservoir (granites intrusion stage) normal faults trending parallel to the dykes are initiated. These faults tilt the upper‐crustal blocks along with the former dyke swarm and associated lava pile. Finite‐element modelling shows that a decrease of magma pressure in a circular cavity may lead, as in Skye, to a change from a regional strike‐slip to a local rift‐type normal stress regime.