The electrical structure of the Slave craton

Jones, Alan G.; Lezaeta, Pamela; Ferguson, Ian J.; Chave, Alan D.; Evans, Robert; García, Xavier; Spratt, J.

doi:10.1016/j.lithos.2003.08.001

Cited by 134 publications

(133 citation statements)

References 81 publications

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“…Jun Korenaga is thanked for providing a preprint of a paper containing new analyses of olivine creep parameters. (Li and Burke, 2006) > 150 km (Chen et al, 2007) Consistent with 250 km (Bruneton et al, 2004a) S-Receiver function~ 250-300 km (Kumar et al, 2007) Magnetotelluric (MT) 230 km (Miensopust et al, 2006) 210 km at LdG 260 km average (Jones et al, 2003) 205 km at NAT (Jones, 1999) > 300 km (Korja, 2007) . The LAB may also correlate with a downward extinction of seismic anisotropy (e.g., Gaherty and Jordan, 1995) or a change in the direction of anisotropy (e.g., Debayle and Kennett, 2000a;2000b;Sebai et al, 2006).…”

Section: Discussionmentioning

confidence: 91%

“…Although the MT experiments were initially designed to image the LAB, they led to the discovery of an unusual conductive region at depths of 80-120+ km (the Central Slave Mantle Conductor; CSMC) that is spatially coincident with a geochemically defined ultradepleted harzburgitic layer (Jones et al, 2001;. The inferred base of the CSMC possibly coincides with the graphite-diamond boundary, suggesting that carbon interconnected along grain boundaries may represent the conductive mantle phase (Jones et al, 2003).…”

Section: Slave Cratonmentioning

confidence: 99%

“…Using the average MT response for stations distributed throughout the Slave craton, Jones et al (2003) showed that a minimum of five homogeneous layers are required to fit the data. Based on their average model (see Fig.…”

Section: Slave Cratonmentioning

confidence: 99%

“…12), the electrical LAB beneath the Slave craton is located on average at 260 (225 -310) km and represents a decrease from 300 (150 -600) ⋅m to 75 (55 -95) ⋅m. Noting that the majority of the MT stations are located in the southern Slave region, Jones et al (2003) suggested that the lithospheric thickness at Lac de Gras in the centre of the craton, is less than this value based on the data from the ocean-bottom instrument located in the lake. A LAB at around 200 km is suggested by Jones et al (2003), consistent with petrological observations .…”

Section: Slave Cratonmentioning

confidence: 99%

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The elusive lithosphere–asthenosphere boundary (LAB) beneath cratons

Eaton

Darbyshire

Evans

et al. 2009

Lithos

392

288

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The lithosphere-asthenosphere boundary (LAB) is a first-order structural discontinuity that accommodates differential motion between tectonic plates and the underlying mantle. Although it is the most extensive type of plate boundary on the planet, its definitive detection, especially beneath cratons, is proving elusive. Different proxies are used to demarcate the LAB, depending on the nature of the measurement. Here we compare interpretations of the LAB beneath three The seismic LAB beneath cratons is typically regarded as the base of a high-velocity mantle lid, although some workers infer its location based on a distinct change in seismic anisotropy.Surface-wave inversion studies provide depth-constrained velocity models, but are relatively insensitive to the sharpness of the LAB. The S-receiver function method is a promising new seismic technique with complementary characteristics to surface-wave studies, since it is 2 sensitive to sharpness of the LAB but requires independent velocity information for accurate depth estimation. Magnetotelluric (MT) observations have, for many decades, imaged an "electrical asthenosphere" layer at depths beneath the continents consistent with seismic lowvelocity zones. This feature is most easily explained by the presence of a small amount of water in the asthenosphere, possibly inducing partial melt. Depth estimates based on various proxies considered here are similar, lending confidence that existing geophysical tools are effective for mapping the LAB beneath cratons.

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Section: Discussionmentioning

confidence: 91%

Section: Slave Cratonmentioning

confidence: 99%

Section: Slave Cratonmentioning

confidence: 99%

Section: Slave Cratonmentioning

confidence: 99%

See 2 more Smart Citations

The elusive lithosphere–asthenosphere boundary (LAB) beneath cratons

Eaton

Darbyshire

Evans

et al. 2009

Lithos

392

288

View full text Add to dashboard Cite

show abstract

“…The method allowed qualitative recognition of the main 3-D conductivity anomalies which served as important input information for the forward 3-D modeling in both the Andean subduction zone and the Slave Craton [Lezaeta, 2001;Jones et al, 2003].…”

Section: Discussionmentioning

confidence: 99%

Beyond magnetotelluric decomposition: Induction, current channeling, and magnetotelluric phases over 90°

Lezaeta

Haak

2003

J. Geophys. Res.

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[1] This paper presents a method to examine strong current channeling affecting the magnetotelluric (MT) impedances, going beyond existing tensor decomposition schemes. The method allows recognition of elongated conductors in the crust and is also useful for a qualitative recognition of general three-dimensional (3-D) high-conductivity anomalies. This has been tested with synthetic data from 3-D and 2-D anisotropic models. The current channeling analysis has been applied to MT data collected in the Andean subduction zone, where the Atacama megafault system close to the Pacific Ocean and oriented subparallel to the coast line is located. The analysis suggests the presence of vertical dike-like conductors of limited lateral extent along the fault zone. Several MT sites distributed along the faults have impedance phases of the electric field tangential to the local azimuth far exceeding 90°at longer periods. We are able to explain this as being the result of strong current channeling producing magnetic distortion due to an electromagnetic coupling between the conductive ocean and the continental elongated conductors.

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Lithospheric architecture of the Slave craton, northwest Canada, as determined from an interdisciplinary 3‐D model

Snyder

Hillier

Kjarsgaard

et al. 2014

Geochem Geophys Geosyst

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Regional-scale geologic structures characteristic of mantle lithosphere within cratons found in continent interiors are interpreted using geo-registered diverse data sets from the Slave craton of northwest Canada. We developed and applied a new method for mapping seismic discontinuities in three dimensions using multiyear observations at sparse, individual broadband receivers. New, fully 3-D conductivity models used all available magnetotelluric data. Discontinuity surfaces and conductivity models were geo-registered with previously published P-wave and surface-wave velocity models to confirm first-order structures such as a midlithosphere discontinuity. Our 3-D model to 400 km depth was calibrated by ''drill hole'' observations derived from xenolith suites extracted from kimberlites. A number of new structural discontinuities emerge from direct comparison of coregistered data sets and models. Importantly, we distinguish primary mantle layers from secondary features related to younger metasomatism. Subhorizontal Slave craton layers with tapered, wedge-shaped margins indicate construction of the craton core at 2.7 Ga by underthrusting and flat stacking of lithosphere. Mapping of conductivity and metasomatism in 3-D, the latter inferred via mineral recrystallization and resetting of isotopic ages in xenoliths, indicates overprinting of the primary layered structures. The observed distribution of relatively conductive mantle at 100-200 km depths is consistent with pervasive metasomatism; vertical ''chimneys'' reaching to crustal depths in locations where kimberlites erupted or where Au mineralization is known.

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The electrical structure of the Slave craton

Cited by 134 publications

References 81 publications

The elusive lithosphere–asthenosphere boundary (LAB) beneath cratons

The elusive lithosphere–asthenosphere boundary (LAB) beneath cratons

Beyond magnetotelluric decomposition: Induction, current channeling, and magnetotelluric phases over 90°

Lithospheric architecture of the Slave craton, northwest Canada, as determined from an interdisciplinary 3‐D model

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