Magnetic anomalies associated with salt tectonism, deep structure and regional tectonics in the Maritimes Basin, Atlantic Canada

2013 ◽  
Vol 26 (2) ◽  
pp. 320-337 ◽  
Author(s):  
N. Hayward ◽  
S. A. Dehler ◽  
A. C. Grant ◽  
Paul Durling
Keyword(s):  
Deep Structure ◽  
Magnetic Anomalies ◽  
Atlantic Canada ◽  
Maritimes Basin ◽  
Regional Tectonics

NEW RESULTS OF POLYMETALLIC, PGE AND REE MINERALIZATION RESEARCH IN THE SUWAŁKI ANORTHOSITE MASSIF (NE POLAND)

2018 ◽  
Vol 472 (472) ◽  
pp. 271-284 ◽  
Author(s):  
Janina Wiszniewska ◽  
Ewa Krzemińska ◽  
Olga Polechońska ◽  
Zdzisław Petecki ◽  
Michał Ruszkowski ◽  
...  
Keyword(s):  
Deep Structure ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Ore Deposits ◽  
Borehole Data ◽  
Ne Poland ◽  
Anorthosite Massif ◽  
Deep Boreholes ◽  
Thick Overburden ◽  
Rock Suite

Suwałki Anortosite Massif (SAM) occurs in the crystalline basement of NE Poland within 200 km of the magmatic, Mesoproterozoic AMCG (anorthosite–mangerite–charnockite–granite) rock suite terrane called the Mazury Complex. SAM was discovered as a result of the drilling research of the prominent negative magnetic and gravimetric anomalies. There is an extensive negative anomaly of both potential fields related to the anorthosite massif. Gravimetric anomaly is surrounded by the bands of positive anomalies caused by rocks with elevated densities, such as granitoids, monzondiorites and granodiorites. A negative magnetic anomaly is surrounded by the bands of positive anomalies with significant amplitudes, particularly strongly marked from the south, west and north. Positive magnetic anomalies are associated with the presence of rocks with proven strong magnetic susceptibility due to the content of ferrolites (ilmenite-magnetite rocks) with accompanying Fe-Cu-Ni-Co sulphide mineralization. Fe-Ti-(V) ore deposits in the SAM were discovered in the early 1960s, in the region of Krzemianka and Udryn, but also Jeleniewo and Jezioro Okrągłe, under a thick overburden of Phanerozoic sedimentary rocks within small positive magnetic anomalies. These deposits were documented in about 100 deep boreholes to a depth of 2300 m, and the resources in C1 + C2 category were estimated for about 1.5 billion tons of titanium-magnetite ores with vanadium, mainly in the Krzemianka and Udryn ore fields. The model age obtained by the Re-Os NTIMS method for Fe-Ti-V ores and sulphides from the Krzemianka and Jezioro Okrągłe ore deposits was 1559 ±37 Ma with an initial ratio of 187Os/188Os = 1.16 ±0.06. This age was recognized as the age of the entire Suwałki Massif. Despite many years of research, the deep structure and the form of the massif has not been fully recognized. At present, geophysical and geological 3D modelling of borehole data is carried out using the OasisMontaj (Geosoft) software package. The 3D model is generated in the GeoModeller 3D application (Intrepid Geophysics) in order to recognize the geological correctness and interpretation of magnetic-gravity anomalies of the whole massif and its cover.

scholarly journals Crustal Density and Susceptibility Structure beneath Achankovil Shear Zone, India

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 6) ◽  
Author(s):  
M. Prasad ◽  
C. P. Dubey ◽  
K. B. Joshi ◽  
V. M. Tiwari
Keyword(s):  
Shear Zone ◽  
Western Ghats ◽  
Deep Structure ◽  
Far East ◽  
Joint Modeling ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Gravity Gradient ◽  
Crustal Density ◽  
The Western Ghats

Abstract The Southern Granulite Terrain (SGT) is a large tract of exposed Archean continental crust, divided into the Madurai Block (MB), Trivandrum Block (TB), and Nagercoil Block (NB). These crustal domains are linked with the NW-SE trending Achankovil Shear Zone (AKSZ). We combine gravity and magnetic data with previously published ground observations and geochronological data to re-evaluate the crustal architecture, evolution of the AKSZ, and possible extension of AKSZ into Madagascar. Analyses indicate that the long wavelength trends of the magnetic anomalies originate at ~20 km depth of different SGT blocks. These observations are corroborated with the gravity as well as computed gravity gradient anomalies. The presence of khondalite outcrops in Trivandrum Block implies that high magnetization crust is the main source of positive magnetic anomalies. Such magnetic anomalies advocate that SGT preserves the remanent of Archean crustal blocks in South India, a part due to variation in thermal and geochemical processes. The AKSZ, TB, and MB exhibit contrasting magnetic crustal signatures. The joint modeling results reveal a three-layered crustal configuration with varying Moho ranging from 41 to 34 km in NE to SW, respectively. It is also noted that AKSZ is a narrow and deep structure near to the Western Ghats Escarpment while it is wide and shallow in the far-east, which implies that the evolution of the Western Ghats is a late geological event.

scholarly journals Correlation between lithospheric magnetic anomalies and tectonic structures in the Norwegian-Greenland region of the Arctic

2018 ◽  
Vol 9 (4) ◽  
pp. 1163-1172 ◽  
Author(s):  
D. Yu. Abramova ◽  
L. M. Abramova ◽  
S. V. Filippov
Keyword(s):  
Geomagnetic Field ◽  
Large Scale ◽  
Deep Structure ◽  
Magnetic Anomalies ◽  
Field Vector ◽  
Point Of View ◽  
The Arctic ◽  
Tectonic Structures ◽  
Champ Satellite ◽  
Marginal Seas

The studies of the deep structure and tectonics of the Arctic are important for solving the fundamental problems of modern geodynamics and developing its natural resources. This region is also of interest from the geopolitical point of view, in particular, considering the boundaries of the marginal seas. Our study aims to investigate the lithospheric (anomalous) geomagnetic field in the Norwegian-Greenland region of the Arctic and to correlate the identified anomalies with tectonic structures located in the region under study. The database includes the CHAMP satellite measurements of the modulus of the total geomagnetic field vector (the satellite operated at the altitude of ~280 km). This article describes the satellite data processing method applied to distinguish between the lithospheric part and other components of the geomagnetic field. Map showing the total vector modulus of the lithospheric field has been constructed for the studied area. The article discusses the possible nature of the lithospheric magnetic anomalies and their relation to the processes that occur under the territory of Greenland. According to our interpretation of the maps, the geomagnetic field anomalies are related to the modern large-scale geological and tectonic structures located in the studied area. The obtained results can facilitate further comprehensive geological and geophysical studies and contribute to modeling of the evolution of the lithosphere.

scholarly journals DEEP STRUCTURE OF OSBORN PLATO (INDIAN OCEAN) ACCORDING TO MAGNETIC AND GRAVITY MODELING

2020 ◽  
Vol 48 (2) ◽  
pp. 69-90
Author(s):  
A. M. Gorodnitskiy ◽  
A. N. Ivanenko ◽  
O. V. Levchenko ◽  
I. A. Veklich ◽  
N. A. Shishkina
Keyword(s):  
Deep Structure ◽  
Classical Model ◽  
Bouguer Anomaly ◽  
Magnetic Layer ◽  
Magnetic Anomalies ◽  
Oceanic Lithosphere ◽  
Gravity Modeling ◽  
Multi Stage ◽  
Southern Central ◽  
Density Modeling

According to the data of hydro-magnetic surveying and satellite altimetry, using the original technology for solving the inverse problem, 2D models of the magnetic layer for three latitudinal profiles crossing the submarine plateau of Osborne in the southern, central and northern parts were constructed. Density modeling for these three profiles was carried out using the available worldwide data on free air anomalies, reduced to the Bouguer anomaly. On all profiles, zones of increased effective magnetization with complex morphology are confidently distinguished. The distinguished sources of magnetic anomalies are tending toward two deep horizons. The upper one corresponds to layer 2 of the classical model of the magnetic layer of the oceanic lithosphere and is a source of local magnetic anomalies of both signs. The lower magnetic layer, the bottommost part of which approximately corresponds to the depth of the Moho surface according to density modeling, is apparently composed of serpentinites. The crust is broken by a system of sub-meridional faults, to which confined deep magnetic bodies, possibly associated with serpentinite protrusions. The revealed laterally inhomogeneous deep structure of the magnetic layer of the Osborne plateau and the adjacent NER segment testifies to their complex multi-stage volcano-tectonic evolution, which continues to present day.

scholarly journals Martin Harold Phillips Bott. 12 July 1926—20 October 2018

2019 ◽  
Vol 67 ◽  
pp. 89-117
Author(s):  
Anthony Brian Watts
Keyword(s):  
Oil And Gas ◽  
Deep Structure ◽  
Oil And Gas Industry ◽  
Magnetic Anomalies ◽  
Earth’S Crust ◽  
Field Methods ◽  
Crust And Upper Mantle ◽  
Geological Interpretation ◽  
Gravity And Magnetic ◽  
Earth's Crust

Martin Bott was a geophysicist who made fundamental contributions to our understanding of gravity and magnetic anomalies and their geological interpretation. His research on the deep structure of the Earth's crust was both pioneering and innovative, and he showed how field geophysical measurements could be used to address geological problems such as the mechanics of granite emplacement, sedimentary basin formation and mountain building. When he began his research, the use of gravity and magnetic anomalies to understand deep crustal structure was in its infancy and largely confined to research laboratories in the oil and gas industry. Four decades later his lifetime efforts have seen the emergence of potential field methods as one of the principal means of constraining the structure, stress state and long-term strength of the Earth's crust and upper mantle in continents and oceans. Martin was an inspiring undergraduate teacher and outstanding supervisor, as reflected by his many research students who went on to prominent leadership positions in academia, government and industry. He leaves a legacy of more than 150 scientific papers in peer-reviewed journals and a lucidly written and beautifully illustrated textbook. As well as his many scientific achievements, Martin was an accomplished mountaineer, a dedicated churchgoer and an avid gardener. He saw no conflict between his science and his enduring Christian faith.

Sign in / Sign up

Export Citation Format

Share Document