Rheology of ice II at low differential stresses

Details Rheology of ice II at low differential stresses Rheology of ice II at low differential stresses

Dec 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agufm.p31a0954k&link_type=abstract

American Geophysical Union, Fall Meeting 2004, abstract #P31A-0954

Physics

5430 Interiors (8147), 5460 Physical Properties Of Materials, 6020 Ice, 6062 Satellites, 3902 Creep And Deformation

Scientific paper

Knowledge of the rheology of high-pressure phases of water ice is crucial for understanding the thermal structure and internal dynamics within medium- and large-size icy moons of the outer planets. In previous studies of ice at relatively high differential stresses, the flow laws of the several high-pressure phases were inferred to lie mainly in the dislocation creep regime. In this study, we have carried out creep experiments of fine-grained ice II at confining pressures of 200-250 MPa and temperatures of 200-220 K using a gas-medium triaxial deformation apparatus to measure rheology at lower stress conditions. We make fine-grained ice II by multiple I-II transitions at lower temperatures and larger overpressure conditions from the equilibrium boundary. Microstructures of deformed ice II aggregates were examined by cryogenic SEM. Clear differences in creep behavior between ice II made by single and triple I-II transitions were observed at stresses of 4-18 MPa and strain rates of 10-8-10-7 s-1. In the former case, the stress exponent is about 5, which is consistent with the flow law previously obtained at differential stresses above 20 MPa. In the latter case, the ice II is much weaker and the stress exponent is about 2.4. Preliminary estimates of the grain size of ice II are about 50 micron and 10 micron, respectively. These experimental results imply that the grain-size sensitive creep of ice II dominates plastic strain at low stress conditions, making ice II the second phase of ice (after ice I) to manifest a change from a grain-size insensitive rheology to a weaker grain-size sensitive rheology at low stresses and finer grain sizes. The implications for icy moons are towards more convective instability, and lower internal stresses, temperatures, and/or grain sizes.

Affiliated with

Also associated with

No associations

Rating

Rheology of ice II at low differential stresses does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Rheology of ice II at low differential stresses, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rheology of ice II at low differential stresses will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1452938