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Use of the analytic signal to identify magnetic anomalies due to kimberlite pipes

Pierre Keating and Pascal Sailhac
Use of the analytic signal to identify magnetic anomalies due to kimberlite pipes
Geophysics (January 2004) 69 (1): 180-190

Abstract

The magnetic signature of most kimberlite pipes is, at high magnetic latitudes, a circular anomaly. At lower magnetic latitudes, it becomes asymmetric; and at the magnetic equator, the anomaly is mostly negative. The shape of the anomaly is also influenced by the presence of remanent magnetization. For a vertical cylinder, the shape of the analytic signal of the magnetic field is nearly independent of field orientation and remanence and always results in a compact, almost circular anomaly. A simple pattern recognition technique, based on a first-order regression over a moving window, between the analytic signal of the observed magnetic field and the theoretical analytic signal of a magnetic vertical cylinder is an effective tool to identify potential targets. Results where the correlation coefficient between the analytic signal and the theoretical analytic signal within a moving window are above a certain threshold are retained, and additional criteria can later be used to refine the target selection. The method's practical utility is demonstrated by applying it to three different sites. The first is a well-documented area located at high magnetic latitude (Ontario, Canada), the second is at low magnetic latitude (West Africa), and the last one is an area where many pipes have a negative magnetization (Lac de Gras, Canada).


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 69
Serial Issue: 1
Title: Use of the analytic signal to identify magnetic anomalies due to kimberlite pipes
Affiliation: Geological Survey of Canada, Ottawa, ON, Canada
Pages: 180-190
Published: 200401
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 31
Accession Number: 2005-021954
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Accessed on March 7, 2005
Illustration Description: illus. incl. 4 tables
N48°12'00" - N48°17'60", W79°55'60" - W79°46'60"
Secondary Affiliation: Institut de Physique du Globe de Strasbourg, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 200511
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