Salt Interpretation with Special Focus on Magnetic Data, Nordkapp Basin, Barents Sea

Fichler, Christine; Rueslåtten, Håkon; Gram, C.; Ingebrigtsen, A.; Olesen, Odleiv

doi:10.3997/2214-4609-pdb.166.c_op_06

Cited by 6 publications

(4 citation statements)

References 4 publications

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“…there are units from the Lower Cretaceous (Johansen et al, 1992). This result confirms that the magnetic effects generated by the contact of saline diapirs with the Cretaceous layers, that contain ferrous minerals (siderite), are predominant when compared with those generated by discontinuities in other layers with low magnetic susceptibility (Fichler et al, 2007).…”

Section: Multiridge Analysis Of the Nordkapp Diapirssupporting

confidence: 75%

“…Other types of geophysical methods, such as magnetic and gravity techniques, can give important contributions to the interpretation and modeling of the whole salt structures, provided that data are at high resolution (e.g., Fichler et al, 2007; Geletti et al, 2014; Gernigon et al, 2011; Olesen et al, 2010; Stadtler et al, 2014). In addition, magnetic methods have low costs compared to seismic methods.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Field Imaging of Salt Structures at Nordkapp Basin, Barents Sea

Paoletti

Milano

Baniamerian

et al. 2020

Geophysical Research Letters

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We show that high-resolution aeromagnetic surveys, although rarely employed in the research of salt structures, may be an effective and low-cost tool for mapping diapirism. A multiscale analysis of a high-resolution magnetic data set at Nordkapp Basin in the Barents Sea, allows a clear reconstruction of the main salt diapirs of the basin using Multiridge and Compact Depth from Extreme Points methods. We provide a 3-D model of the diapirs extended from 500 to 4,000 m below sea level, characterized by a general low magnetization contrast no larger than −0.08 A/m. The 3-D model is consistent with the salt top depth estimated by 2-D seismics, with borehole data and with the 2-D gravity model of the Uranus diapir. Our imaging shows the capability of the magnetic method that gives new and comprehensive pictures of salt diapirism.

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Section: Multiridge Analysis Of the Nordkapp Diapirssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Magnetic Field Imaging of Salt Structures at Nordkapp Basin, Barents Sea

Paoletti

Milano

Baniamerian

et al. 2020

Geophysical Research Letters

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“…Gravity and gravity gradiometry are gaining attention due to their ability to improve salt imaging (e.g., Pratson et al, 1998, Huston andSestak, 1999;Millegan, 2005;O'Brien et al, 2005;Saad, 2006;Fichler et al, 2007;Hokstad et al, 2011). The effect is due to the contrasting density of salt compared with surrounding sediments.…”

mentioning

confidence: 99%

“…Salt interpretation including magnetic data has been rare (Prieto 1998;Fichler et al, 2007;Gernigon et al, 2011). Induced magnetic susceptibilities (from now on simply called 'susceptibilities') of sediments are caused by amount and distinct chemical forms of iron bearing minerals in the sediments (cf., Gunn 1997) and exhibit as such almost no depth dependence.…”

mentioning

confidence: 99%

Improved salt imaging in a basin context by high resolution potential field data: Nordkapp Basin, Barents Sea

Stadtler

Fichler

Hokstad

et al. 2014

Geophysical Prospecting

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The seismic imaging of salt diapirs in the Nordkapp Basin gave rise to considerable problems in defining their shape and volume. Independent information was added by integrating the interpretation with high resolution gravity and magnetic data. We developed a novel, iterative workflow, separated into sub‐categories: sediments, salt structures, basement and Moho. Distinctions between the sources of the anomalies from different depths was achieved by utilizing the different decay characteristics of gravity, gravity gradiometry and high resolution magnetic anomalies. The workflow was applied to the southern part of the Nordkapp Basin. It started with the sedimentary model derived from seismics, populated with measured densities and magnetic susceptibilities and a starting model for the base salt. The residual after the removal of this model was interpreted in terms of a crustal model, including flexural isostatic calculations for the Moho with the sedimentary load. The residual after the removal of crustal and early sedimentary model was used to tune the salt model. As these major and minor modelling steps depend on each other, an iterative process was applied to stepwise improve the density and magnetic susceptibility model. The first vertical gradient of gravity and the magnetic field were found to give most information about the cap rock of the diapirs. The improvement in salt imaging, integrated with results from controlled‐source electromagnetic and magneto‐telluric modelling is shown for the salt diapir Uranus, where a well, terminated in the salt, constrains the minimum of the depth to base salt.

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New aeromagnetic and gravity compilations from Norway and adjacent areas: methods and applications

Olesen

Brönner

Ebbing

et al. 2010

PGC

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169

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The Geological Survey of Norway (NGU) has produced new aeromagnetic and gravity maps from Norway and adjacent areas, compiled from ground, airborne and satellite data. Petrophysical measurements on core samples, hand specimens and on in situ bedrock exposures are essential for the interpretation of these maps. Onshore, the most prominent gravity and magnetic anomalies are attributed to lower crustal rocks that have been brought closer to the surface. The asymmetry of the gravity anomalies along the Lapland Granulite Belt and Kongsberg–Bamble Complex, combined with the steep gradient, points to the overthrusted high-density granulites as being the main source of the observed anomalies. The Kongsberg–Bamble anomaly can be traced southwards through the Kattegat to southern Sweden. This concept of gravity field modelling can also be applied to the Mid-Norwegian continental shelf and could partially explain the observed high-density rocks occurring below the Møre and Vøring basins and in the Lofoten area. Extrapolations of Late-Caledonian detachment structures occurring on the mainland can be traced on aeromagnetic and gravimetric images towards the NW across the continental margin. Subcropping Late Palaeozoic to Cenozoic sedimentary units along the mid-Norwegian coast produce a conspicuous magnetic anomaly pattern. The asymmetry of the low-amplitude anomalies, with a steep gradient and a negative anomaly to the east and a gentler gradient to the west, relates the anomalies to gently westward dipping strata. Recent aeromagnetic surveys in the Barents Sea have revealed negative magnetic anomalies associated with shallow salt diapirs. Buried Quaternary channels partly filled with gravel and boulders of crystalline rocks generate magnetic anomalies in the North Sea. The new maps also show that the opening of the Norwegian–Greenland Sea occurred along stable continental margins without offsets across minor fracture zones, or involving jumps in the spreading axis. A triple junction formed at 48 Ma between the Lofoten and Norway Basins.

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Salt Interpretation with Special Focus on Magnetic Data, Nordkapp Basin, Barents Sea

Cited by 6 publications

References 4 publications

Magnetic Field Imaging of Salt Structures at Nordkapp Basin, Barents Sea

Magnetic Field Imaging of Salt Structures at Nordkapp Basin, Barents Sea

Improved salt imaging in a basin context by high resolution potential field data: Nordkapp Basin, Barents Sea

New aeromagnetic and gravity compilations from Norway and adjacent areas: methods and applications

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