Joint inversion of marine magnetotelluric and gravity data incorporating seismic constraints: preliminary results of sub-basalt imaging off the Faroe Shelf

Jegen-Kulcsar, Marion, Hobbs, Richard W., Tarits, Pascal and Chave, Alan (2009) Joint inversion of marine magnetotelluric and gravity data incorporating seismic constraints: preliminary results of sub-basalt imaging off the Faroe Shelf Earth and Planetary Science Letters, 282 . pp. 47-55. DOI 10.1016/j.epsl.2009.02.018.

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Abstract

Breakup of the North Atlantic during the early tertiary was accompanied by widespread and massive magmatism, resulting in the coverage of large areas of the North Atlantic with flood basalts. These flood basalts hamper seismic investigations of underlying sequences and thus the understanding of the rifting, subsidence and evolution of the margin which, in turn, increases the risk for hydrocarbon exploration. In this paper we present a methodology for the simultaneous joint inversion of diverse geophysical datasets, i.e. free air gravity and magnetotelluric soundings (MT) using seismic a priori constraints. The attraction of the joint inversion approach is that different geophysical measurements are sensitive to different properties of the sub-surface, so through joint inversion we significantly reduce the null space and produce a single model that fits all datasets within a predefined tolerance. Using sensitivity analysis of synthetic data, we show how each data set contains complementary important information of the supra and sub-basalt structure. While separate inversions of individual datasets fail to image through the basalt layer, our joint inversion approach leads to a much improved sub-basalt structure. Application of the joint inversion algorithm to satellite gravity data and MT data acquired on the FLARE10 seismic line south west of Faroe islands supports the existence of a 1 km to 2 km thick low velocity region that might be indicative of the existence of a sedimentary basin underneath the basalt layer. Though in this paper we demonstrate the use of joint inversion on a sub-basalt target, we believe it has wider applicability to other areas where conventional seismic imaging fails.

Document Type: Article
Keywords: joint inversion, marine electromagnetics, sub-basalt imaging, North Atlantic, Faroe-Shetland Trough
Research affiliation: OceanRep > SFB 574
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
OceanRep > SFB 574 > N01
Refereed: Yes
DOI etc.: 10.1016/j.epsl.2009.02.018
ISSN: 0012-821X
Projects: Future Ocean, SFB574, SIMBA
Contribution Number:
ProjectNumber
SFB 574148
Date Deposited: 17 Sep 2009 10:59
Last Modified: 10 Feb 2017 09:31
URI: http://eprints.uni-kiel.de/id/eprint/1911

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