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Diffusion creep of fine‐grained garnetite: Implications for the flow strength of subducting slabs
Author(s) -
Wang Zichao,
Ji Shaocheng
Publication year - 2000
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 - 10.1029/1999gl008474
Subject(s) - creep , diffusion creep , geology , diffusion , grain boundary diffusion coefficient , grain boundary , grain boundary sliding , grain size , lithosphere , materials science , mineralogy , thermodynamics , composite material , microstructure , seismology , tectonics , physics , geomorphology
Creep experiments were performed on synthetic fine‐grained garnetite to investigate the flow strength of the Earth's subducting slabs. Experiments were conducted at temperatures ( T ) of 1373–1543 K and total pressure ( P ) of 0.1 MPa in controlled atmospheres of f O 2 =10 −17 ‐10 –8 MPa. The mechanical data indicate a grain‐size sensitive diffusion flow and the creep behavior can be described by an equation of the form: where T in Kelvin, d in meter, σ and f O 2 in MPa. Based on the diffusivities ( D ) calculated from creep and diffusion experiments, we proposed that grain boundary diffusion is the dominant mechanism for high temperature creep of the fine‐grained garnetite. Normalized creep strength of the garnetite is found to be comparable to those of feldspar and olivine in diffusion creep regime, suggesting that garnetite may not form a strong layer in the subducted oceanic lithosphere if it deforms by grain boundary diffusion creep.