Tectonic interpretation of regional conductivity anomalies

Brown, Colin

doi:10.1007/bf00689858

Cited by 56 publications

(15 citation statements)

References 157 publications

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“…Their presence was modeled in other Brazilian regions as below the Parana basin (Stanley et al, 1985;Beamish and Travassos, 1992) and the Solimoes Basin (Porsani, 1991). Otherwise crustal resistivities of 200-1000 ohm.m are compatible with the figures found in other cratonic regions (Haak and Hutton, 1986;Hyndman and Shearer, 1989;Brown, 1994). Moreover conductors situated below a resistive and homogeneous upper and medium crust with resistivities compatible to ours have been reported extensively in the literature (Simpson, 1998) and are usually explained as a result of the presence of saline fluids, sulfide and graphite.…”

Section: Discussionsupporting

confidence: 55%

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Geoelectric structure beneath limestones of the Sao Francisco Basin, Brazil

Travassos

Menezes

2014

Earth Planet Sp

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A reconnaissance MT survey was conducted in the southern portion of the Sao Francisco Sedimentary Basin, Brazil, for mapping the subsurface structure. The objective was to provide a regional model and in helping to select areas to be further surveyed with seismics. The data collected at seven EMAP-style spreads of 500 m, with an average spacing of 30 km. The field procedure allowed for the correction of statics and the production of 7 inverted models, smooth representations of the regional structure as seen below each site. A 2-D forward model tested and refined the regional structure revealed by the inversions and yielded an earth composed of 4 main geologic units. A 100 ohm.m limestone layer on the top of 20 ohm.m shales, followed by a 1000-200 ohm.m structured basement. Crustal resistivities do not change until reaching depths of more than 30 km. The model ends at a conductive half-space of 30 ohm.m. A suture zone between an orogenic belt and the Sao Francisco craton was modeled below the sedimentary section bringing its know limits 60 km to the east.

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Section: Discussionsupporting

confidence: 55%

“…Crustal conductors are very common throughout the earth's crust (Haak and Hutton, 1986;Schwarz, 1990;Brown, 1994;Haak et al, 1996). Their presence was modeled in other Brazilian regions as below the Parana basin (Stanley et al, 1985;Beamish and Travassos, 1992) and the Solimoes Basin (Porsani, 1991).…”

Section: Discussionmentioning

confidence: 99%

Geoelectric structure beneath limestones of the Sao Francisco Basin, Brazil

Travassos

Menezes

2014

Earth Planet Sp

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“…Other reviews covering aspects of marine EM include: Filloux (1973Filloux ( , 1979, Cox (1980), Fonarev (1982), Law (1983), Constable (1990), Chave et al (1991), Brown (1994), Palshin (1996), Heinson (1999), Constable and Srnka (2007) and Constable (2010).…”

Section: Introductionmentioning

confidence: 98%

Marine Electromagnetic Studies of Seafloor Resources and Tectonics

Key

2011

Surv Geophys

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The past decade has been a period of rapid growth for marine electromagnetic (EM) methods, predominantly due to the industrial adoption and promotion of EM as a valuable tool for characterizing offshore hydrocarbon reservoirs. This growth is illustrated by a database of marine EM publications spanning from the early developments in the 1960's to the present day; while over 300 peer-reviewed papers on marine EM have been published to date, more than half of these papers have been published within the last decade. This review provides an overview of these recent developments, covering industrial and academic use of marine EM for resource exploration and tectonic investigations, ranging from acquisition technology and modeling approaches to new physical and geological insights learned from recent data sets.

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“…In tectonically active regions, small percentages of partial melt and free saline fluids form conducting structures that are distinct for different tectonic environments (e.g., Hjelt and Korja 1993;Brown 1994). In stable regions ancient tectonic processes have often left electrically conducting traces of collisions of various crustal units revealing the location of palaeosuture zones or even more specific tectonic assemblages such as foredeeps (e.g., Boerner et al 1996).…”

Section: Introductionmentioning

confidence: 99%

How is the European Lithosphere Imaged by Magnetotellurics?

Korja

2007

Surv Geophys

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I review recent investigations on the electrical conductivity of the lithosphere and asthenosphere in Europe. The principal method in the reviewed studies is the magnetotelluric method, but in many cases other electromagnetic methods (e.g., magnetovariational profilings and geomagnetic depth soundings) have provided additional information on subsurface conductivity or have been the primary method. The review shows that the magnetotelluric method has been used, and is being used, in all kinds of environments and for many different processes shaping the crust and lithosphere. The crust is very heterogeneous, both with respect to the scale of conductive/resistive features and interpretations: research targets vary from Archaean palaeostructures to ongoing processes. The European database of the depth to the lithosphere-asthenosphere boundary (LAB) in Europe is updated, and a new map showing lateral variations of the depth of LAB is provided. The compilation shows that (1) the Phanerozoic European lithosphere, with considerable variations (45-150 km), is much thinner than the Precambrian European lithosphere, (2) the Trans-European Suture Zone is a major electrical border in Europe separating electrically (as well as geophysically and geologically in general) two quite different settings, (3) the thinnest lithosphere is found under the extensional Pannonian Basin (45-90 km), (4) in most of the East European Craton there are no indications of a high conductivity zone in upper mantle. In many regions there is no information at all on upper mantle conductivity, which calls for pan-European projects to operate arrays of simultaneously recording instruments with long recording periods (2-8 months) and dense spatial sampling (20-50 km).

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Tectonic interpretation of regional conductivity anomalies

Cited by 56 publications

References 157 publications

Geoelectric structure beneath limestones of the Sao Francisco Basin, Brazil

Geoelectric structure beneath limestones of the Sao Francisco Basin, Brazil

Marine Electromagnetic Studies of Seafloor Resources and Tectonics

How is the European Lithosphere Imaged by Magnetotellurics?

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