3D inversion modelling of the Nechako Basin, British Columbia, magnetotelluric data set

Drew, Matthew Charles (2012) 3D inversion modelling of the Nechako Basin, British Columbia, magnetotelluric data set. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (48MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The Nechako Basin is an intermontane basin situated in south central British Columbia, Canada. Due to a desire for an alternative source of employment stemming from the impact of the mountain pine beetle on the forestry industry, the government of British Columbia has commissioned several geophysical and geological surveys of the area in order to assess its hydrocarbon potential. This sedimentary basin is covered with a layer of volcanic extrusive rocks which renders seismic methods nearly ineffective. As an alternative, a magnetotelluric (MT) survey was performed in order to determine subsurface conductivity and structure. Data from this survey were used in this thesis to produce a 3D conductivity model of the subsurface, by running multiple inversions with varied parameters. Data from four profiles as well as additional sites filling in gaps between profiles were used: Profile A ran west of Nazko. Profile B ran south of Nazko, Profile C ran north-west of Nazko, and Profile D ran east from Nazko toward Quesnel. Models from inversion of this MT survey show sensitivity to thicker surface volcanic rock and show where these bodies may thin or pinch out (e.g. conductivity at the west end of profile A and south end of Profile B). Additionally potential faulting and partial melt is seen in the subsurface, in profile D and at depth between profiles A and C respectively. 3D inversion models have provided information in addition to previous 2D results, giving a different placement of features out of the restricted plane of 2D inversion and showing lateral extent of conductivity anomalies, thus contributing to hydrocarbon exploration in the Nechako Basin.

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