Mitchell Brogan

B. Sc. Honours Thesis

Gravity Modelling of the Liscomb "Satellite" Pluton

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The Liscomb "Satellite" Pluton is a small granitoid mass located northwest of the main Liscomb Complex in central Nova Scotia. Detailed gravity data has been obtained over the smaller pluton, and from the surrounding area. Due to the density contrast that normally exists between intrusive bodies and their metamorphosed hosts it is possible to model the subsurface geometry of the intrusive body using Bouguer gravity data. The aim of this study has been to model the subsurface geometry of the Liscomb "Satellite" Pluton and to establish its physical connection to the main Liscomb Complex.

During this study 96 gravity stations were surveyed over 22 km with an average station spacing of 200 m. Over approximately 11 km of the survey gravity data was collected on a regional scale at a station spacing of 200 to 1000 m. Approximately 11 km of the survey was conducted on, or in the immediate vicinity, of the Liscomb "Satellite" Pluton using a station spacing of 100 to 200 m. In most cases the maximum amount of error associated with the Bouguer gravity values is + 0.05 mgal.

Bouguer gravity contours show a -5.0 mgal anomaly over the Liscomb "Satellite" Pluton. Gravity modelling of this anomaly indicates that the pluton is an oval-shaped vertical cylinder with a convex upper surface. Results also indicate that the minimum depth extent of the pluton is 20 km, and that the pluton is connected to the main Liscomb Complex at a depth of 0.5 km. However, the connection between the pluton and main Liscomb Complex does not appear to be consistent along the entire southern margin of the pluton.

Kwywords:
Pages: 40
Supervisor:  Patrick J. C. Ryall