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Switches in the minimum compressive stress direction induced by overpressure beneath a low‐permeability fault zone
Author(s) -
Collettini C.,
De Paola N.,
Goulty N. R.
Publication year - 2006
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 - 10.1111/j.1365-3121.2006.00683.x
Subject(s) - geology , overpressure , extensional definition , seismology , fault (geology) , permeability (electromagnetism) , stress field , petrology , stress (linguistics) , compressive strength , echelon formation , tectonics , composite material , linguistics , philosophy , physics , genetics , materials science , finite element method , membrane , biology , thermodynamics
The Zuccale fault is a gently east‐dipping normal fault exposed on Elba. Its displacement of 7–8 km occurred from the mid‐Miocene to the Early Pliocene and the fault has been exhumed from a depth of 3–6 km. A complex hydrofracture system exposed in the footwall block consists of three orthogonal vein sets: two vertical sets trending N–S and E–W and one sub‐horizontal. The veins show a crack‐and‐seal texture and mutually cross‐cut each other. Throughout the period when the Zuccale fault was active, the regional stress field was extensional with the minimum principal stress oriented E–W, consistent only with the N–S trending set of vertical hydrofractures. We attribute the three sets of orthogonal fractures beneath the low‐permeability phyllosilicate‐rich fault core to switches in the minimum compressive stress direction induced by cyclic build‐up and release of overpressure.