Decrepitation and crack healing of fluid inclusions in San Carlos olivine

Journal Article · Mon Sep 10 00:00:00 EDT 1990 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JB095iB10p15623· OSTI ID:6099840

Wanamaker, B J ^[1]; Wong, Tengfong ^[2]; Evans, B ^[3]

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1. Lawrence Livermore National Lab., CA (USA)
2. State Univ. of New York, Stony Brook (USA)
3. Massachusetts Institute of Technology, Cambridge (USA)

Fluid inclusions break, or decrepitate, when the fluid pressure exceeds the least principal lithostatic stress by a critical amount. After decrepitation, excess fluid pressure is relaxed, resulting in crack arrest; subsequently, crack healing may occur. The authors developed a linear elastic fracture mechanics model to analyze new data on decrepitation and crack arrest in San Carlos Olivine, compared the model with previous fluid inclusion investigations, and used it to interpret some natural decrepitation microstructures. The common experimental observation that smaller inclusions may sustain higher internal fluid pressures without decrepitating may be rationalized by assuming that flaws associated with the inclusion scale with the inclusion size. According to the model, the length of the crack formed by decrepitation depends on the lithostatic pressure at the initiation of cracking, the initial sizes of the flaw and the inclusion, and the critical stress intensity factor. Further experiments show that microcracks in San Carlos olivine heal within several days at 1,280 to 1,400{degree}C; healing rates depend on the crack geometry, temperature, and chemistry of the buffering gas. The regression distance of the crack tip during healing can be related to time through a power law with exponent n = 0.6. Chemical changes which become apparent after extremely long heat-treatments significantly affect the healing rates. Many of the inclusions in the San Carlos xenoliths stretched, decrepitated, and finally healed during uplift. The crack arrest model indicates that completely healed cracks had an initial fluid pressure of the order of 1 GPa. Using the crack arrest model and the healing kinetics, they estimate the ascent rate of these xenoliths to be between 0.001 and 0.1 m/s.

• OSTI ID: 6099840
• Journal Information: Journal of Geophysical Research; (USA), Vol. 95:B10; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CRACKS
CLOSURES
FRACTURE MECHANICS
MATHEMATICAL MODELS
OLIVINE
CRACK PROPAGATION
GROUND UPLIFT
INCLUSIONS
INHIBITION
MICROSTRUCTURE
RESERVOIR FLUIDS
RESERVOIR PRESSURE
STRESS INTENSITY FACTORS
STRESS RELAXATION
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
CRYSTAL STRUCTURE
FLUIDS
IRON COMPOUNDS
IRON SILICATES
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
MECHANICS
MINERALS
OXYGEN COMPOUNDS
RELAXATION
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
580000* - Geosciences