Magnetic signatures related to orogenic gold mineralization, Central Lapland Greenstone Belt, Finland

Airo, Meri-Liisa; Mertanen, S.

doi:10.1016/j.jappgeo.2007.10.003

Cited by 30 publications

(12 citation statements)

References 9 publications

(12 reference statements)

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“…The use of high remanent magnetization in modelling is necessary in order to fit the measured magnetic data since high susceptibility values from the gabbroic rocks and volcanites cannot explain the measured high magnetic anomalies. Pyrrhotite‐bearing sediments often have a high remanent magnetization and low resistivity, which can explain both the very high magnetic anomalies and the low resistivities found (e.g., Airo and Mertanen 2008).…”

Section: Discussionmentioning

confidence: 99%

Combined magnetic, electromagnetic and resistivity study over a highly conductive formation in Orrivaara, Northern Sweden

Persson

Lundin

Pedersen

et al. 2011

Geophysical Prospecting

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Different geophysical methods were used to determine the characteristics of a highly conductive structure in Northern Sweden, first discovered on airborne data. Airborne electromagnetic (very low frequency) data indicate a high conductivity structure coincident with low magnetic patterns. The airborne data were processed in different ways to enhance various structures/features. In particular we introduce a new transformation to current density that is suitable for delineating conductive structures. Ground measurements of the total magnetic field, radiomagnetotelluric measurements and resistivity imaging provided valuable information that was used in the compilation of a new bedrock map over the area. The results of our measurements indicate that the conducting structure consists of metasedimentary rocks containing thin horizons of pyrrhotite and graphite.

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Section: Discussionmentioning

confidence: 99%

Combined magnetic, electromagnetic and resistivity study over a highly conductive formation in Orrivaara, Northern Sweden

Persson

Lundin

Pedersen

et al. 2011

Geophysical Prospecting

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“…2 Digital elevation map of the study area structural and geological observations, they serve as a means of locating anomalous sources: their depths, dimension, magnetization and in providing lithological information and structural frameworks for inferring information about tectonic evolution, mineralization, etc. (Jaques et al 1997;Aitken and Betts 2009;Gobashy and Al-Garni 2008;Airo and Mertanen 2007;Sultan et al 2009). …”

Section: High-resolution Aeromagnetic (Hram) Data: Processing and Intmentioning

confidence: 99%

Existence of a possible subsurface ring complex in the northwestern part of the Nigerian Younger Granite province: a contribution from aeromagnetic and remote sensing data

2014

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The study area lies within the north-western part of the Nigerian Younger Granite province. It is bounded by latitude 10°30′N and 11°00′N and longitude 8°00′E and 9°00′E. Previous geological and geophysical studies that were carried out in the study area focused mainly on the ring complexes with surface exposure while nothing is known about those without the surface exposure. This has resulted in gap in geo-scientific knowledge which this study aimed to fulfill. First vertical derivative (FVD) and Euler deconvolution of the aeromagnetic data along with processed DEM were used to achieve this purpose. Results of the interpretation revealed a magnetic anomaly, almost circular in shape, with characteristics that are similar to the anomalies that spatially coincide with the prominent ring complexes but without the outcrops that are associated with the complexes. This anomaly is interpreted to be an unexposed ring. Lineaments revealed by the results are mainly oriented in the E-W, NE-SW and NW-SE. The lineaments in the NE-SW and its conjugate are the most developed lineament system. Presence of ring complexes on and along the lineaments favours the opinion that the emplacement sites of the complexes are influenced by the reactivated Pan-African shear zones and transcurrent faults. In particular, the cross-over of major lineaments at the nonoutcropping anomaly may suggest a very weak zone that probably allowed the volcanic eruption that initiated the emplacement of the unexposed ring complex. Results of the Euler deconvolution suggest a cylindrical-like body for the unexposed ring complex, which is consistent with pluton geometry, and a depth that range from outcrop to 1,200 m for it.

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“…Province-and continental-scale compilations of magnetic data sets provide a useful framework for identifying regional crustal structures that control distribution of mineralization and favorable geological environments (e.g., Hildenbrand et al 2000;Chernicoff and Nash 2002;Betts et al 2004;Sandrin and Elming 2006;Airo and Mertanen 2008;Mertanen 2008, 2009;Anand and Rajaram 2006;Anand et al 2009), particularly if these data sets are integrated with other geophysical data.…”

Section: Resource Explorationmentioning

confidence: 99%

Mapping and Interpretation of the Lithospheric Magnetic Field

Purucker

Clark

2010

Geomagnetic Observations and Models

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We review some of the controversial and exciting interpretations of the magnetic field of the earth's lithosphere occurring in the four year period ending with the IAGA meeting in Sopron in 2009. This period corresponds to the end of the Decade of Geopotential Research, an international effort to promote and coordinate a continuous monitoring of geopotential field variability in the near-Earth environment. One of the products of this effort has been the World Digital Magnetic Anomaly Map, the first edition of which was released in 2007. A second, improved, edition is planned for 2011. Interpretations of the lithospheric magnetic field that bear on impacts, tectonics, resource exploration, and lower crustal processes are reviewed. Future interpretations of the lithospheric field will be enhanced through a better understanding of the processes that create, destroy, and alter magnetic minerals, and via routine measurements of the magnetic field gradient. IntroductionThe magnetic field originating in the earth's lithosphere is part of the earth's magnetic field complex, a dynamic system (Friis-Christensen et al. 2009) dominated by the interaction of the earth's magnetic field dynamo with that of the sun's. The lithospheric field M.E. Purucker ( ) Raytheon at Planetary Geodynamics Lab, Goddard Space Flight Center, Code 698, Greenbelt, MD 20771, USA e-mail: michael.e.purucker@nasa.gov is dominated by static (on a human time scale) contributions that typically represents less than 1% of the overall magnitude of the magnetic field complex, and originate from rocks in the crust and locally, the uppermost mantle. Interpretation of the lithospheric magnetic field is used in (1) structural geology and geologic mapping, and extrapolation of surface observations of composition and structure, (2) resource exploration and 3) plate tectonic reconstructions and geodynamics.This article is designed as a review describing recent progress in mapping and interpreting the lithospheric magnetic field, and also includes some highlights from the 2009 IAGA meeting in Sopron, Hungary. Since IAGA meets every four years, we have designed this review to highlight progress in the four year period from 2005 through 2009, although references to earlier important works are not neglected, especially in the area of resource exploration. Several reviews bearing on the mapping and interpretation of the lithospheric magnetic field have appeared between 2005 and 2009. Review articles within books and encyclopedias have included those within the Encyclopedia of Geomagnetism and Paleomagnetism (Gubbins and

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Magnetic signatures related to orogenic gold mineralization, Central Lapland Greenstone Belt, Finland

Cited by 30 publications

References 9 publications

Combined magnetic, electromagnetic and resistivity study over a highly conductive formation in Orrivaara, Northern Sweden

Combined magnetic, electromagnetic and resistivity study over a highly conductive formation in Orrivaara, Northern Sweden

Existence of a possible subsurface ring complex in the northwestern part of the Nigerian Younger Granite province: a contribution from aeromagnetic and remote sensing data

Mapping and Interpretation of the Lithospheric Magnetic Field

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