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Conductivity structure of the lithosphere-asthenosphere boundary beneath the eastern North American margin

Conductivity structure of the lithosphere-asthenosphere boundary beneath the eastern North American margin
Conductivity structure of the lithosphere-asthenosphere boundary beneath the eastern North American margin
Tectonic plate motion and mantle dynamics processes are heavily influenced by the characteristics of the lithosphere-asthenosphere boundary (LAB), yet this boundary remains enigmatic regarding its properties and geometry. The processes involved in rifting at passive margins result in substantial alteration of the lithosphere through the transition from continental to oceanic lithologies. Here we employ marine magnetotelluric (MT) data acquired along a ?135 km long profile, offshore Martha’s Vineyard, New England, USA, to image the electrical conductivity structure beneath the New England continental margin for the first time. We invert the data using two different MT 2-D inversion algorithms and present a series of models that are obtained using three different parameterizations: fully unconstrained, unconstrained with an imposed LAB discontinuity and a-priori constrained lithosphere resistivity. This suite of models infers variability in the depth of the LAB, with an average depth of 115 km at the eastern North America passive margin. Models robustly detect a ?350 ?m lithospheric anomalous conductivity zone (LACZ) that extends vertically through the entire lithosphere. Our preferred conductivity model is consistent with regional P-to-S receiver function data, shear-wave velocity, gravity anomalies and prominent geological features. We propose that the LACZ is indicative of paleo lithospheric thinning, either resulting from Kimberlite intrusions associated with rifting and the New England Great Meteor hotspot track, or from shear-driven localized deformation related to rifting.
1525-2027
676-696
Attias, Eric
abf34bba-f99f-47f9-ba89-92df1c488a5e
Evans, Rob L.
38559971-706c-4ea9-a886-13fded783539
Naif, Samir
efb82be7-11b9-45c2-8740-7f2cb2d62896
Elsenbeck, Jimmy
562a1b2e-4ac4-4244-89fc-b1f47a89ab73
Key, Kerry
73dfeafa-0b11-4033-8cf9-49837ae17bb9
Attias, Eric
abf34bba-f99f-47f9-ba89-92df1c488a5e
Evans, Rob L.
38559971-706c-4ea9-a886-13fded783539
Naif, Samir
efb82be7-11b9-45c2-8740-7f2cb2d62896
Elsenbeck, Jimmy
562a1b2e-4ac4-4244-89fc-b1f47a89ab73
Key, Kerry
73dfeafa-0b11-4033-8cf9-49837ae17bb9

Attias, Eric, Evans, Rob L., Naif, Samir, Elsenbeck, Jimmy and Key, Kerry (2017) Conductivity structure of the lithosphere-asthenosphere boundary beneath the eastern North American margin Geochemistry, Geophysics, Geosystems, 18, (2), pp. 676-696. (doi:10.1002/2016GC006667).

Record type: Article

Abstract

Tectonic plate motion and mantle dynamics processes are heavily influenced by the characteristics of the lithosphere-asthenosphere boundary (LAB), yet this boundary remains enigmatic regarding its properties and geometry. The processes involved in rifting at passive margins result in substantial alteration of the lithosphere through the transition from continental to oceanic lithologies. Here we employ marine magnetotelluric (MT) data acquired along a ?135 km long profile, offshore Martha’s Vineyard, New England, USA, to image the electrical conductivity structure beneath the New England continental margin for the first time. We invert the data using two different MT 2-D inversion algorithms and present a series of models that are obtained using three different parameterizations: fully unconstrained, unconstrained with an imposed LAB discontinuity and a-priori constrained lithosphere resistivity. This suite of models infers variability in the depth of the LAB, with an average depth of 115 km at the eastern North America passive margin. Models robustly detect a ?350 ?m lithospheric anomalous conductivity zone (LACZ) that extends vertically through the entire lithosphere. Our preferred conductivity model is consistent with regional P-to-S receiver function data, shear-wave velocity, gravity anomalies and prominent geological features. We propose that the LACZ is indicative of paleo lithospheric thinning, either resulting from Kimberlite intrusions associated with rifting and the New England Great Meteor hotspot track, or from shear-driven localized deformation related to rifting.

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Accepted/In Press date: 18 January 2017
e-pub ahead of print date: 31 January 2017
Published date: 1 February 2017
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 404952
URI: http://eprints.soton.ac.uk/id/eprint/404952
ISSN: 1525-2027
PURE UUID: 48f02b96-13be-4bc5-bbb8-0e8650ae4162

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Date deposited: 20 Jan 2017 10:19
Last modified: 31 Oct 2017 05:01

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Contributors

Author: Eric Attias
Author: Rob L. Evans
Author: Samir Naif
Author: Jimmy Elsenbeck
Author: Kerry Key

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