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Origin, damping, and pattern of development of faults in granite
Author(s) -
Granier Thérèse
Publication year - 1985
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc004i007p00721
Subject(s) - geology , massif , echelon formation , fault plane , shear (geology) , seismology , brittleness , fault (geology) , joint (building) , petrology , geochemistry , structural engineering , materials science , engineering , composite material
Observations of brittle fractures in the granite of the Massif de la Borne as well as in other rocks allow us to discuss the different hypotheses regarding the origin of faults. It seems that all faults originate by shear along a preexisting plane which can be an important fracture (joint, former fault) or a microflaw (pore, grain boundary). The shear on the plane gives rise to an array of en echelon cracks that makes the rock less resistant and permits the lengthening of the fault. We also found an arrangement of “horsetail” fractures damping the movements on the faults. We then propose a pattern for the development of the faults. They originate on preexisting plane and propagate by initiating en echelon cracks. The movements are damped by horsetails which permit, by faults connection in relays, the creation of larger faults.