Regional Magnetic Anomalies and Geology in Fennoscandia: A discussion

1972 ◽  
Vol 9 (3) ◽  
pp. 219-232 ◽  
Author(s):  
R. P. Riddihough
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Fracture Zones ◽  
West Central ◽  
Anomaly Map ◽  
The Baltic

A contoured magnetic anomaly map constructed from aeromagnetic profiles reflects the established tectonic patterns of the Fennoscandian region and permits speculations about such features as continental discontinuities colinear with oceanic fracture zones. An interpretation of the most outstanding magnetic anomaly of the region, in west-central Sweden, shows that its source is associated with a Precambrian anorogenic complex and has an unusually high magnetization. Magnetic similarities between the Baltic and Canadian shields are briefly discussed.

Analysis of the Czech magnetic anomaly data obtained by ground-based and airborne magnetic surveys

2020 ◽  
Author(s):  
Pavel Hejda ◽  
Dana Čápová ◽  
Eva Hudečková ◽  
Vladimír Kolejka
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Data File ◽  
Ore Deposits ◽  
Substantial Contribution ◽  
Magnetic Survey ◽  
Contour Maps ◽  
Anomaly Map ◽  
Ground Magnetic ◽  
Airborne Survey

<p>The modern epoch of ground magnetic surveying activity on the Czech territory was started by the Institute of Geophysics by setting up a fundamental network of the 1<sup>st</sup> order in 1957-58. It consists of 199 points and was reoccupied in 1976-78 and 1994-96. The anomaly maps were constructed by subtraction of the IGRF model.</p><p>Extensive aeromagnetic measurements have been performed from 1959 to 1972 by permalloy probe of Soviet provenience. The accuracy of the instrumentation was about (and often above) 10 nT. The second period of airborne survey started in 1976. Thanks to the deployment of proton precession magnetometer, the accuracy improved to ~ 2 nT. Since 2004 the measurements were carried out by caesium magnetometer. The data were digitized, known anthropogenic anomalies were cleared away and data were transformed to the regular grid with step 250 m. The final data file of magnetic anomalies ΔT, administered by the Czech Geological Survey, represents a substantial contribution to the exploration of ore deposits and to the structure geology in general.</p><p>In view of the fact that data file of magnetic anomalies was compiled from data acquired by heterogeneous methods in the course of more than 50 years, our recent study is aimed at looking into the homogeneity of the data by comparison them with ground-based magnetic survey. A simple comparison of the contour maps showed good similarity of the large regional anomalies. For more detailed analysis, the variation of ΔT in the neighbourhood of all points of the fundamental network was inspected and the basic statistic characteristics were computed. Summary results as well as several examples will be presented accordingly as the INSPIRE compliant services and eventually as the user-friendly web map application and made available on the CGS Portal http://mapy.geology.cz/ and on the updated web of the CzechGeo/EPOS consortium www.czechgeo.cz. Incorporating the map into the World Digital Magnetic Anomaly Map (WDMAM – IAGA) is also under consideration. This data will also be interesting for the EPOS.</p>

Magnetic anomaly lineations and fracture zones deduced from vector magnetic anomalies in the West Enderby Basin

1996 ◽  
Vol 108 (1) ◽  
pp. 265-273 ◽  
Author(s):  
Yoshifumi Nogi ◽  
Nobukazu Seama ◽  
Nobuhiro Isezaki ◽  
Yoichi Fukuda
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Fracture Zones ◽  
The West

scholarly journals Detection of ferromagnetic objects in local magnetic anomaly of the Baltic Sea

2008 ◽  
Vol 15 (2) ◽  
pp. 77-82 ◽  
Author(s):  
Mirosław Wołoszyn
Keyword(s):  
Magnetic Field ◽  
Mathematical Model ◽  
Baltic Sea ◽  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Mobile Platforms ◽  
The Baltic Sea ◽  
Magnetic Systems ◽  
The Baltic ◽  
The Mathematical Model

Detection of ferromagnetic objects in local magnetic anomaly of the Baltic Sea In geological researches several kinds of methods are applied to discovering the natural resources. Planes, helicopters and UAVs (UnmAnned Vehicle) are used in researches in large areas. The gravity, electromagnetic and magnetic methods, which are used in geological researches, are presented in this paper. The special attention was paid to magnetic systems installed on mobile platforms. The magnetic field of the Earth obtained from mathematical model was compared to the real magnetic field in the selected part of the Baltic Sea. The results of the calculations showed that the mathematical model of the Earth's magnetic field does not consider local magnetic anomalies. The strong local magnetic anomalies cause serious problems with detection of underwater objects. Special problems appear in the magnetic system on a helicopter, which are presented in this paper.

scholarly journals Acquisition procedures, processing methodologies and preliminary results of magnetic and ROV data collected during the TOMO-ETNA experiment

2016 ◽  
Vol 59 (4) ◽  
Author(s):  
Danilo Cavallaro ◽  
Luca Cocchi ◽  
Mauro Coltelli ◽  
Filippo Muccini ◽  
Cosmo Carmisciano ◽  
...  
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
High Amplitude ◽  
Structural Features ◽  
Magnetic Survey ◽  
Remotely Operated Vehicle ◽  
Ne Sicily ◽  
Mt Etna ◽  
Source Study ◽  
Anomaly Map

<p>The TOMO-ETNA experiment was devised for the investigation of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands, through an active source study. In this experiment, a large amount of geophysical data was collected both inland and in the Ionian and Tyrrhenian Seas for identifying the major geological and structural features offshore Mt. Etna and NE Sicily. One of the oceanographic cruises organized within the TOMO-ETNA experiment was carried out on the hydrographic vessel “Galatea” by Italian Navy. During the cruise a detailed magnetic survey and a set of ROV (remotely operated vehicle) dives were performed offshore Mt. Etna. The magnetic survey allowed the compilation of a preliminary magnetic map revealing a clear direct relationship between volcanic structures and high frequency magnetic anomalies. Significant positive magnetic anomalies were identified offshore the Timpa area and along the easternmost portion of the Riposto Ridge <span>and</span> correlated to a primitive volcanic edifice and to shallow volcanic bodies, respectively. On the whole, the magnetic anomaly map highlights a clear SW-NE decreasing trend, where high amplitude positive magnetic anomaly pattern of the SW sector passes, northeastwardly, to a main negative one. ROV dives permitted to directly explore the shallowest sectors of the Riposto Ridge and to collect several videos and seafloor samples, allowing us to identify some locally developed volcanic manifestations.</p>

Intermediate‐scale magnetic anomalies of the Earth

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2817-2830 ◽  
Author(s):  
J. Arkani‐Hamed ◽  
D. W. Strangway
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Anomaly ◽  
Correlation Coefficients ◽  
Sedimentary Basins ◽  
Magnetic Anomalies ◽  
The Earth ◽  
Asymmetric Component ◽  
Anomaly Map ◽  
Well Correlation

Four separate magnetic anomaly maps of the earth are derived from magnetometer satellite data acquired at dawn and at dusk using two different altitude ranges. The magnetic anomalies on the two dawn maps (or dusk maps) are well correlated for spherical harmonics of degree less than 51, suggesting that the time varying external magnetic field and leveling noise have negligible effects on these harmonics. Dawn and dusk maps have an appreciable asymmetric component for harmonics of degree n ⩽ 5 and n = 15 and 17, arising from the quasi‐stable external magnetic field. Dawn‐dusk covariant harmonics of degree [Formula: see text] with signal‐to‐noise ratios greater than 1.5 correlate well. Correlation coefficients are higher than 0.75, implying that these harmonics can be repeatably derived. A global scalar magnetic anomaly map is derived based on these harmonics. The map is then converted to a magnetic susceptibility anomaly map by an inversion technique. The susceptibility anomalies delineate the ocean‐continent differences as well as the boundaries of tectonic provinces, modern uplifts, crustal rifts, and sedimentary basins.

scholarly journals Mapping and interpretation of satellite magnetic anomalies from POGO data over the Antarctic region

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
M. E. Purucker ◽  
R. R. B. von Frese ◽  
P. T. Taylor
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Oceanic Lithosphere ◽  
Crustal Thickness ◽  
Time Varying ◽  
Antarctic Region ◽  
Magnetic Field Data ◽  
Anomaly Map ◽  
The Antarctic ◽  
Lateral Variations

A satellite magnetic anomaly map made using the POGO magnetic field data is compared to three maps made using Magsat data. A total of 14 anomalies with magnitudes greater than 3 nT can be identified in all four of the maps poleward of 60°S latitude. Forward models of the Antarctic continental and oceanic lithosphere are produced which use magnetic crustal thickness based on seismic and heat flow data, and which also use the distribution of the Cretaceous Quiet Zone from marine geophysics. These simple models can explain significant parts of eight of the 14 identified anomalies. The remaining anomalies may be caused by lateral variations of magnetization, inadequate models of the magnetic crustal thickness, or remanent magnetizations in directions other than the present field. In addition, contamination of the magnetic anomaly maps by fields of time-varying external origin (and their corresponding internal parts) is still a significant problem in the Antarctic region.

Sign in / Sign up

Export Citation Format

Share Document