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Geology topics

M. A. Daley

Publications and source records attributed to M. A. Daley.

2 recordsLinked to original sources

Thin sectioning and surface replication of ice at low temperature.

We have developed a new technique for making thin sections and surface replicas of ice at temperatures well below 273 K. Cyanoacrylate glue forms a strong bond with ice and glass at 245 K, eliminating the need to fix the sample to the thin-section slide by melting and freezing. Surface replicas are made by melting away sample material once the glue has cured. Glue replicas are permanent and highly detailed, making them suitable for microstructural and textural studies at room temperature . Thin sections glued with cyanoacrylate glue are comparable in quality to melted-on sections. The ability to make thin sections without melting sample material is important in textural and microstructural studies of ice deformed at low temperatures because of annealing effects we have observed during conventional section making.

Journal of Glaciology

Inelastic properties of ice Ih at low temperatures and high pressures

The aim of our research programme is to explore the rheological behavior of H 2 O ices under conditions appropriate to the interiors of the icy satellites of the outer planets in order to give insight into their deformation. To this end, we have performed over 100 constant-strain-rate compression tests at pressures to 500 MPa and temperatures as low as 77 K. At P > 30 MPa, ice I h fails by a shear instability producing faults in the maximum shear stress orientation and failure strength typically is independent of pressure. This unusual faulting behavior is thought to be connected with phase transformations localized in the shear zones. The steady-state strength follows rheological laws of the thermally-activated power-law type, with different flow law parameters depending on the range of test temperatures. The flow laws will be discussed with reference to the operating deformation mechanisms as deduced from optical-scale microstructures and comparison with other work.

Journal de Physique Colloques