Experimental Constraints on the Strength of the Lithospheric Mantle

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/2009JB006873· OSTI ID:1019792

Mei, S; Suzuki, A; Kohlstedt, D; Dixon, N; Durham, W

To provide a better understanding of rheological properties of mantle rocks under lithospheric conditions, we carried out a series of experiments on the creep behavior of polycrystalline olivine at high pressures ({approx}4-9 GPa), relatively low temperatures (673 {le} T {le} 1273 K), and anhydrous conditions, using a deformation-DIA. Differential stress and sample displacement were monitored in situ using synchrotron X-ray diffraction and radiography, respectively. Experimental results were fit to the low-temperature plasticity flow law. On the basis of this analysis, the low-temperature plasticity of olivine deformed under anhydrous conditions is well constrained by our data with a Peierls stress of {sigma}{sub P} = 5.9 {+-} 0.2 GPa, a zero-stress activation energy of E{sub k}(0) = 320 {+-} 50 kJ mol{sup -1}, and A{sub P} = 1.4 x 10{sup -7} s{sup -1} MPa{sup -2}. Compared with published results for high-temperature creep of olivine, a transition from low-temperature plasticity to high-temperature creep occurs at {approx}1300 K for a strain rate of {approx}10{sup -5} s{sup -1}. For a geological strain rate of 10{sup -14} s{sup -1}, extrapolation of our low-temperature flow law to 873 K, the cutoff temperature for earthquakes in the mantle, yields a strength of {approx}600 MPa. The low-temperature, high-stress flow law for olivine in this study provides a solid basis for modeling tectonic processes occurring within Earth's lithosphere.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1019792
• Report Number(s): BNL--95638-2011-JA
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Vol. 115; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ACTIVATION ENERGY
CREEP
EARTHQUAKES
EXTRAPOLATION
OLIVINE
PLASTICITY
SIMULATION
STRAIN RATE
SYNCHROTRONS
TECTONICS
X-RAY DIFFRACTION
national synchrotron light source