Delineating the alteration zone at the big easy prospect using geophysical methods

Wall, Adam (2017) Delineating the alteration zone at the big easy prospect using geophysical methods. Masters thesis, Memorial University of Newfoundland.

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The Big Easy Prospect is a low-sulphidation (LS) style epithermal system located along the northern extension of the Burin Peninsula High Sulphidation Belt in Newfoundland. It is believed to have formed during an extensional magmatic episode during the rifting of Avalonia from Gondwana in the late Neoproterozoic era. Despite its age, the Big Easy is well preserved which is likely due to rapid burial shortly after it was formed. Overlying sediments have since been eroded exposing what is believed to be the paleosurface of the Big Easy LS system. However, the property is covered extensively with overburden, forests, bogs, and ponds resulting in limited outcrop exposure. Therefore, delineating the alteration zone has proved to be challenging. The alteration zone associated with the auriferous mineralization should be detectable through the use of various geophysical methods. Several surveys were conducted over the property, including magnetics, gravity, and ground penetrating radar (GPR) in an attempt to gain a better understanding of the lateral and vertical extent of the alteration zone. These surveys were followed by two-dimensional forward and inverse modelling. Results of the magnetic survey mainly revealed features caused by mafic dykes. Since mafic dykes are noted to be spatially related to faulting in the area, a new potential boundary for the eastern extent of the epithermal alteration is identified. Bathymetry profiles of the bogs and lakes were created using data collected from the GPR survey. This allowed for proper corrections in the gravity data as well as more accurate modelling of the near subsurface. The gravity survey was the most effective for estimating the depth of the alteration zone since the altered material was slightly less dense than the surrounding units but further drilling is required to confirm this conclusion.

Item Type: Thesis (Masters)
Item ID: 12996
Additional Information: Includes bibliographical references (pages 113-117).
Keywords: gravity, magnetics, GPR
Department(s): Science, Faculty of > Earth Sciences
Date: May 2017
Date Type: Submission
Library of Congress Subject Heading: Hydrothermal alteration -- Measurement -- Newfoundland and Labrador; Geophysics -- Methodology

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