Geological modeling of the new CHAMP magnetic anomaly maps using a geographical information system technique

Hemant, Kumar; Maus, Stefan

doi:10.1029/2005jb003837

Cited by 99 publications

(111 citation statements)

References 74 publications

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“…They could not completely explain the observed anomalies just by induced magnetisation of the crust. This result is also confirmed by the recent analysis of CHAMP magnetic anomaly maps over Europe (Hemant and Maus, 2004). There is also evidence from the modelling results over western and central Africa (Hemant and Maus, 2004) that either the magnetised lower crust extends deeper, or magnetisation extends into the upper mantle, or significant remanent magnetisation of the lower crust is also contributing to the observed anomaly.…”

Section: Bulk Remanent Magnetisation Modelsupporting

confidence: 77%

“…This result is also confirmed by the recent analysis of CHAMP magnetic anomaly maps over Europe (Hemant and Maus, 2004). There is also evidence from the modelling results over western and central Africa (Hemant and Maus, 2004) that either the magnetised lower crust extends deeper, or magnetisation extends into the upper mantle, or significant remanent magnetisation of the lower crust is also contributing to the observed anomaly. Due to non-uniqueness, it is generally difficult to separate the individual contribution of induced and remanent magnetisation to the observed anomaly (Maus and Haak, 2003).…”

Section: Bulk Remanent Magnetisation Modelsupporting

confidence: 77%

“…Next, using the global seismic crustal structure, a vertically integrated susceptibility (VIS) model is computed by taking the product of susceptibility and thickness at each point of the region. All Precambrian and Phanerozoic provinces of the world are assigned susceptibility values according to the modelling procedure described in Hemant and Maus (2004). To model the oceans, the oceanic crust is divided into three layers following White et al (1992).…”

Section: Global Vertically Integrated Susceptibility Modelmentioning

confidence: 99%

“…The crustal model for the oceanic region is same as used for derivation of VIS model. The intensity and remanent magnetisation vectors used in this paper are taken from Hemant and Maus (2004).…”

Section: Bulk Remanent Magnetisation Modelmentioning

confidence: 99%

“…The VIS values for the oceans are computed by multiplying the susceptibility values of the individual oceanic layers with their average thicknesses. The global VIS map is derived by knitting together the VIS values for the continents and oceanic regions (Hemant and Maus, 2004;Hemant, 2003Hemant, (http://www.diss.fuberlin.de/2003). Fig.…”

Section: Global Vertically Integrated Susceptibility Modelmentioning

confidence: 99%

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Why no anomaly is visible over most of the continent–ocean boundary in the global crustal magnetic field

Hemant

Maus

2005

Physics of the Earth and Planetary Interiors

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Section: Bulk Remanent Magnetisation Modelsupporting

confidence: 77%

Section: Bulk Remanent Magnetisation Modelsupporting

confidence: 77%

Section: Global Vertically Integrated Susceptibility Modelmentioning

confidence: 99%

Section: Bulk Remanent Magnetisation Modelmentioning

confidence: 99%

Section: Global Vertically Integrated Susceptibility Modelmentioning

confidence: 99%

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Why no anomaly is visible over most of the continent–ocean boundary in the global crustal magnetic field

Hemant

Maus

2005

Physics of the Earth and Planetary Interiors

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The deep crust beneath the Trans‐European Suture Zone from a multiscale magnetic model

Milano

Fedi

Fairhead³

2016

JGR Solid Earth

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We present a 3‐D interpretation of the deep magnetic sources beneath the main geological structure of central‐eastern Europe, the “Trans‐European Suture Zone” (TESZ). We used a multiscale analysis of aeromagnetic data, based on a multiscale data set generated by upward continuation of the European and Mediterranean Magnetic Project data set from 5 to 100 km altitude. We also computed the multiscale total gradient |∇T| of the multiscale field. Both of the multiscale data sets allow us to discriminate the main crustal contributions to the field at various scales, and we showed that at large altitudes the field is dominated by the sole effect of the TESZ. The multiridge geometric method was very useful in studying the complex features of the main crustal interfaces, either shallow or deep. The interpreted interfaces are largely agreement with geological models based on seismic surveys and, in some cases, complete the models out of the analyzed region. In order to estimate the deepest source depths in the TESZ region, we applied the multiridge method to the large scales (50–100 km altitude), obtaining a set of singular points at depths ranging between 35 and 40 km. Considering the heat flow trend and the geological models around the TESZ area, we found a meaningful correspondence among the location of the estimated singular points and the most abrupt variations and complex morphology features of the Moho boundary. The multiridge estimates are consistent with known structural information and can be used for a 3‐D representation of the Moho depth along the TESZ.

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Magnetism at Depth: A View from an Ancient Continental Subduction and Collision Zone

McEnroe

Robinson

Church

et al. 2018

Geochem Geophys Geosyst

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Recent sophisticated global data compilations and magnetic surveys have been used to investigate the nature of magnetization in the lower crust and upper mantle. Two approaches to constraining magnetizations are developed, providing minimum (0.01 SI) and maximum (0.04 SI) susceptibility estimates, given some assumed thickness (15+ km here). These values are higher than are found in many continental rocks. Are there rocks deeper in the crust or upper mantle that are more magnetic than expected, or are the model assumptions incomplete? What is the magnetic behavior of deep‐crustal and upper mantle rocks, when slightly cooler than the Curie or Néel temperatures of their magnetic minerals, after being exhumed from locations of high‐grade metamorphism at greater depth? Different sets of equilibrium metamorphic minerals can be considered that would form under different conditions. Results on 1,501 samples from the Western Gneiss Region (WGR) Norway, mainly from mafic and ultramafic bodies subducted to depths of 60–200 km and temperatures of 750 up to 950°C at the very highest pressures, show that rocks did not fully equilibrate to the dominant metamorphic‐facies conditions. There is a large variation in petrophysical properties, oxide minerals, and mineral assemblages in WGR samples, though they cannot explain the broad high‐amplitude (deep‐seated) anomalies measured in this region. The presence of magnetite, and exsolved titanohematite and hemoilmenite in samples, shows those magnetic phases are preserved even at eclogite‐facies conditions, in part because complete eclogite‐facies equilibrium was rarely achieved.

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Geological modeling of the new CHAMP magnetic anomaly maps using a geographical information system technique

Cited by 99 publications

References 74 publications

Why no anomaly is visible over most of the continent–ocean boundary in the global crustal magnetic field

Why no anomaly is visible over most of the continent–ocean boundary in the global crustal magnetic field

The deep crust beneath the Trans‐European Suture Zone from a multiscale magnetic model

Magnetism at Depth: A View from an Ancient Continental Subduction and Collision Zone

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