Record number :
2326724
Title of article :
Thermally induced brittle deformation in oceanic lithosphere and the spacing of fracture zones
Author/Authors :
Choi، نويسنده , , Eun-seo and Gurnis، نويسنده , , Michael، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2008
Pages :
12
From page :
259
To page :
270
Abstract :
Brittle deformation of oceanic lithosphere due to thermal stress is explored with a numerical model, with an emphasis on the spacing of fracture zones. Brittle deformation is represented by localized plastic strain within a material having an elasto-visco-plastic rheology with strain softening. We show that crustal thickness, creep strength, and the rule governing plastic flow control the formation of cracks. The spacing of primary crack decreases with crustal thickness as long as it is smaller than a threshold value. Creep strength shifts the threshold such that crust with strong creep strength develops primary cracks regardless of crustal thicknesses, while only a thin crust can have primary cracks if its creep strength is low. For a thin crust, the spacing of primary cracks is inversely proportional to the creep strength, suggesting that creep strength might independently contribute to the degree of brittle deformation. Through finite versus zero dilatation in plastic strain, associated and non-associated flow rule results in nearly vertical and V-shaped cracks, respectively. Changes in the tectonic environment of a ridge system can be reflected in variation in crustal thickness, and thus related to brittle deformation. The fracture zone-free Reykjanes ridge is known to have a uniformly thick crust. The Australian-Antarctic Discordance has multiple fracture zones and thin crust. These syntheses are consistent with enhanced brittle deformation of oceanic lithosphere when the crust is thin and vice versa.
Keywords :
Thermal Stress , fracture zone , Oceanic lithosphere , Brittle deformation
Journal title :
Earth and Planetary Science Letters
Journal title :
Earth and Planetary Science Letters
Serial Year :
2008
Link To Document :
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