Darcy E. Baker

1994 - The David Barlow Memorial Award

B. Sc. Honours Thesis

Fluid inclusions and microstructure of flexural-slip bedding-concordant veins within the Ovens Anticline, Lunenburg, Nova Scotia

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Fluid inclusions and microstructure of flexural-slip bedding-concordant quartz veins (FSBCVs) from the Ovens Anticline of the Meguma Group, were assessed and provide data on conditions and mechanisms of flexural-slip folding. These veins formed within a saddle reef type setting along movement horizons and are constrained as having formed during flexural-slip folding.

Geobarometric results from planar fluid inclusion assemblages indicate that fluid pressure fluctuated and supralithostatic fluid pressures were present. Pressure results, when combined with an independent Tt, range from 0.5 to 5.0 kbars. The fluid was mixed H₂O-NaCl-CO₂-CH₄ type.

FSBCVs coinicide with flexural-slip movement horizons, contain abundant wall-rock inclusion layers (WRIL) that originally were continuous but now are separted by layers of quartz, host preferrentially oriented fluid inclusion planes (FIP), and are composed of elongate quartz crystals which have a preferred crystallographic orientation with respect to elongation and possibly with respect to the fold. FIP orientation appears to be related to crystallographic orientation rather than to fold-related stress conditions.

Kwywords: flexural-slip, fluid inclusion, supralithostatic pressure, laminated vein, Meguma Group
Pages: 83
Supervisor: Nicholas Culshaw