The Sudbury Structure is located <10 km from the Grenville Front; the northern boundary of the Grenville metamorphic terrane. Previous geological studies have suggested that late Grenvillian deformation (1000-1070 Ma) of the Sudbury Structure was limited to minor brittle deformation. Olivine diabase dykes, which were intruded at 1238 Ma, before the last pulse of Grenville deformation, cross much of the Sudbury Structure. Any Grenville age deformation of the Sudbury Structure therefore should produce systematic displacements in the geometry of the dykes. This study uses information derived from an aeromagnetic survey of the Sudbury Structure to map and measure fault displacements. Lateral displacements of dyke segments define a progressive increase in fault rotation from NE to SW across the basin. A two-dimensional inversion modelling of magnetic anomaly profiles across segments of the dykes outlines a series of fault blocks with common dip. The dyke dip detected by the inversion models suggests that displacement on the faults included rotation about an axis perpendicular to the trend of the fault. The resulting model of scissor, or splay faults is compatible with previously published palaeomagnetic studies of the olivine dykes in the Sudbury region.
Uranium exploration in the Thelon Basin has been has been revitalized by developments and discoveries reported by AREVA Resources Canada and Cameco Corporation in structurally intercalated metasedimentary and metavolcanic rocks of the Neoarchean Woodburn Lake group and early Paleoproterozoic Ketyet River group south and east of the Aberdeen Subbasin. This study integrates geophysics and geology to model a proposed basement klippe located south of Schultz Lake in central NTS map area 66A. Orthogonal high-resolution ground gravity transects were acquired in 2010, based on initial definition of the structure by a published 2004 geological map. These were integrated with high-resolution aeromagnetic and electromagnetic data from Forum Uranium Corporation, CanVec topographic data, and initial detailed geological observations in 2010 to 2011 by parallel studies under the Northern Uranium for Canada Project, part of the Geomapping for Energy and Minerals (GEM) Program The subsurface geology was computed by integrating surface geological contacts, unconstrained geophysical inversions and forward models. The unconstrained magnetic inversions defined several dyke arrays and suggest a deep seated mafic-to-felsic pluton tentatively assigned to the 2.6 Ga Snow Island Suite. High-resolution electromagnetic data provide strong constraints on near-surface lithology and steeply dipping faults, discriminating between Paleoproterozoic quartzite, Paleoproterozoic grey schist, and Neoarchean arkosic metagreywacke. The forward models, primarily constrained by generic rock properties and the clear gravity signal, support the klippe hypothesis. Further improvement could be achieved with a detailed gravity grid and more site-specific rock properties, and through collaborative integration and feed-back analysis of the full structural mapping data set.
Airborne geophysical surveys provide spatially continuous regional data coverage, which directly reflects subsurface petrophysical differences and thus the underlying geology. A modern geologic mapping exercise requires the fusion of this information to complement what is typically limited regional outcrop. Often, interpretation of the geophysical data in a geological context is done qualitatively using total field and derivative maps. With a qualitative approach, the resulting map product may reflect the interpreter's bias. Source edge detection provides a quantitative means to map lateral physical property changes in potential and non‐potential field data. There are a number of Source edge detection algorithms, all of which apply a transformation to convert local signal inflections associated with source edges into local maxima. As a consequence of differences in their computation, the various algorithms generate slightly different results for any given source depth, geometry, contrast, and noise levels. To enhance the viability of any detected edge, it is recommended that one combines the output of several Source edge detection algorithms. Here we introduce a simple data compilation method, deemed edge stacking, which improves the interpretable product of Source edge detection through direct gridding, grid addition, and amplitude thresholding. In two examples, i.e., a synthetic example and a real‐world example from the Bathurst Mining Camp, New Brunswick, Canada, a number of transformation algorithms are applied to gridded geophysical data sets and the resulting Source edge detection solutions combined. Edge stacking combines the benefits and nuances of each Source edge detection algorithm; coincident or overlapping and laterally continuous solutions are considered more indicative of a true edge, whereas isolated points are taken as being indicative of random noise or false solutions. When additional data types are available, as in our example, they may also be integrated to create a more complete geologic model. The effectiveness of this method is limited only by the resolution of each survey data set and the necessity of lateral physical property contrasts. The end product aims at creating a petrophysical contact map, which, when integrated with known lithological outcrop information, can be led to an improved geological map.
Modern mineral exploration involves making discoveries in geological environments where detecting deposits is increasingly difficult. This study presents an integrated, knowledgedriven prospectivity mapping approach to exploration in the glacial till-covered region of the Quesnel Terrane in British Columbia, Canada. The Quesnel Terrane hosts base and precious metal deposits; however, a ∼20,000 km 2 area consisting of variably thick glacial overburden truncates surface exposure, likely masking buried deposits. Through a combined fuzzy logic and index overlay approach, geophysical, structural, and geochemical criteria were integrated into a prospectivity model. Three concealed porphyry Cu targets were identified in the tillcovered region and were validated by statistical analysis of lake and stream sediment geochemistry. The process of integrating various geoscientific disciplines and identification of targets has provided valuable insight for future exploration in covered regions. Moreover, the adopted approach leverages open-source public datasets, highlighting advantages of utilising such datasets for regional-scale exploration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.