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TitleUpper mantle structure underlying the diamondiferous Slave craton from teleseismic body-wave tomography
AuthorEsteve, C; Schaeffer, A JORCID logo; Audet, P
SourceTectonophysics vol. 757, 2019 p. 187-202,
Alt SeriesNatural Resources Canada, Contribution Series 20190089
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
NTS64E; 64F; 64K; 64L; 64M; 64N; 65C; 65D; 65E; 65F; 65K; 65L; 65M; 65N; 66C; 66D; 66E; 66F; 66K; 66L; 66M; 66N; 67B; 67C; 67F; 67G; 74E; 74F; 74G; 74H; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P; 75; 76; 77; 84E; 84F; 84G; 84H; 84I; 84J; 84K; 84L; 84M; 84N; 84O; 84P; 85; 86; 87; 94E; 94F; 94G; 94H; 94I; 94J; 94K; 94L; 94M; 94N; 94O; 94P; 95; 96; 97; 104H; 104I; 104P; 106A; 106H; 106I; 106P; 107A; 107D; 107E; 107H
AreaGreat Slave Lake; Great Bear Lake; Cape Barrow
Lat/Long WENS-129.0000 -100.0000 72.0000 57.0000
Subjectsstructural geology; geophysics; Archean; crustal studies; continental crust; craton; mantle; seismic models; crustal thickness; geophysical interpretations; seismic interpretations; seismic waves; p waves; s waves; seismic velocities; anomalies; seismic arrays; bedrock geology; structural features; faults; shear zones; lithology; igneous rocks; intrusive rocks; kimberlites; intrusions; metasomatism; terranes; tectonic setting; seismology; earthquakes; epicentres; Slave Craton; Canadian Shield; Lac de Gras Kimberlite Field; Cordillera Deformation Front; Canadian Cordillera; Buffalo Head Terrane; Great Bear Arc; Bathurst Fault; Great Slave Lake Shear Zone; Wopmay Orogen; Thelon Orogen; Taltson-Thelon Magmatic Arc; Coronation Gulf Kimberlite Field; Jericho Kimberlite Field; Southern Slave Kimberlite Field; Western Slave Kimberlite Field; Phanerozoic; Cenozoic; Tertiary; Mesozoic; Cretaceous; Precambrian
Illustrationsgeoscientific sketch maps; seismograms; cross-sections; profiles
ProgramPublic Safety Geoscience Assessing Earthquake Geohazards
Released2019 03 02
AbstractCratons are, by definition, the most tectonically stable and oldest parts of the continental lithosphere on Earth. The Archean Slave craton is located in the northwestern part of the Canadian Shield. The propensity of diamondiferous kimberlite pipes in the Central Slave Craton raises many questions regarding their structural environment and source. Here, we provide the most robust teleseismic P and S body wave tomography models over the Slave craton region based on 20,547 P-wave delay times, 6140 direct S-wave delay times and 3381 SKS delay times. The P-wave model reveals an alternating pattern of relative positive and negative anomalies over a fine scale region within the Central Slave Craton. Furthermore, the P-wave model reveals two fine structures located in the lithosphere beneath the Lac de Gras kimberlite field, with relatively slow anomalies (B-C) that extend from 75 km to 350 km depths with an apparent dip to the north. These relatively slow P-wave anomalies are associated with metasomatised regions within the lithosphere. The most recent kimberlite pipes (75-45 Ma) in the Lac de Gras field are located on steep VP and VS gradients. The S-wave model displays a slow S-wave anomaly lying from 300 km depth to the transition zone beneath the Central Slave Craton. This anomaly is located beneath the Lac de Gras kimberlite field. We suggest that this anomaly is not the cause of the actual kimberlites at the surface since the last eruptions occurred 75-45 Ma ago but may be related to a potential kimberlite magma ascent in the asthenosphere.
Summary(Plain Language Summary, not published)
Cratons are, largely by definition, stable regions in continental interiors, which are typically devoid of seismic activity. However, they often play host to large, economically viable mineral and resource potential. The emplacement of such deposits strikes back to periods of time where these now stable regions were once undergoing some form of tectonic deformation, or active processes. Furthermore, in order to accurately locate infrequent earthquakes within cratons or within more active regions outside their borders, we need accurate 3D velocity models. In this study, we focus on the Slave Craton in Canada's north, the host of many of Canada's economically viable kimberlite deposits, in addition to precious metals, etc. We compute a new, more accurate 3D velocity model geared at examining the deep structure of the craton with respect to the surface location of diamond deposits. We find numerous mantle velocity anomalies that likely represent events associated with the ancient assembly and subsequent attempted reworking of the Slave craton. The velocity models produced through the course of this study will also provide valuable information for more precisely locating seismicity within and around this remote craton.

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