Premium
Transient creep, aseismic damage and slow failure in Carrara marble deformed across the brittle‐ductile transition
Author(s) -
Schubnel A.,
Walker E.,
Thompson B. D.,
Fortin J.,
Guéguen Y.,
Young R. P.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026619
Subject(s) - brittleness , creep , differential stress , materials science , cataclastic rock , coalescence (physics) , overburden pressure , acoustic emission , composite material , dislocation creep , stress (linguistics) , deformation (meteorology) , geology , geotechnical engineering , seismology , fault (geology) , linguistics , physics , philosophy , astrobiology
Two triaxial compression experiments were performed on Carrara marble at high confining pressure, in creep conditions across the brittle‐ductile transition. During cataclastic deformation, elastic wave velocity decrease demonstrated damage accumulation (microcracks). Keeping differential stress constant and reducing normal stress induced transient creep events (i.e., fast accelerations in strain) due to the sudden increase of microcrack growth. Tertiary creep and brittle failure followed as damage came close to criticality. Coalescence and rupture propagation were slow (60–200 seconds with ∼150 MPa stress drops and millimetric slips) and radiated little energy in the experimental frequency range (0.1–1 MHz). Microstructural analysis pointed out strong interactions between intra‐crystalline plastic deformation (twinning and dislocation glide) and brittle deformation (microcracking) at the macroscopic level. Our observations highlight the dependence of acoustic efficiency on the material's rheology, at least in the ultrasonic frequency range, and the role played by pore fluid diffusion as an incubation process for delayed failure triggering.