A Geological Interpretation of the Bouguer Anomaly Field of Newfoundland

10.4095/8585 ◽  
1967 ◽  
Author(s):  
D F Weaver
Keyword(s):  
Bouguer Anomaly ◽  
Anomaly Field ◽  
Geological Interpretation

A detailed gravity profile across the English River Subprovince, northwestern Ontario

1984 ◽  
Vol 21 (2) ◽  
pp. 145-151 ◽  
Author(s):  
V. K. Gupta ◽  
R. B. Barlow
Keyword(s):  
Seismic Data ◽  
Bouguer Anomaly ◽  
Density Data ◽  
Density Measurements ◽  
Anomaly Field ◽  
Red Lake ◽  
Northwestern Ontario ◽  
Crustal Model ◽  
Regional Gravity ◽  
Gravity Profile

This paper presents the results of a detailed gravity profile measured across the two lithotectonic domains of the English River Subprovince from Vermilion Bay to Red Lake, a distance of 190 km, in northwestern Ontario. Along the profile 283 fresh rock samples were collected for density measurements. The density data clearly suggest that there is a measurable and significant density difference between the migmatized metasediments and plutonic rocks.A crustal model based on the seismic data, along the profile, has been used for computing a regional gravity field, which in turn has been used in isolating the residual anomalies from the Bouguer anomaly field. A strong correlation has been found to exist between the residual anomalies, the rock densities, and the surface lithologies. The Northern Supracrustal Domain, which is at its widest (60 km) along the profile, is dominated by a pronounced 15 mGal (150 μm s−2) positive residual anomaly believed to be caused by outcropping, anomalously dense metasediments extending to a modelled depth of approximately 10 km. In the Southern Plutonic Domain the residual anomalies along the profile are small (less than 5 mGal (50 μm s−2)) and limited in depth. The Mystery Lake dome extends to a modelled depth of approximately 2.5 km.

AEROMAGNETIC AND GEOLOGICAL INTERPRETATION OF A SECTION OF THE APPALACHIAN BELT IN CANADA

1967 ◽  
Vol 4 (6) ◽  
pp. 1015-1037 ◽  
Author(s):  
B. K. Bhattacharyya ◽  
B. Raychaudhuri
Keyword(s):  
Prince Edward Island ◽  
Bouguer Anomaly ◽  
Polarization Vector ◽  
Fault System ◽  
Aeromagnetic Data ◽  
Eastern Canada ◽  
Geological Interpretation ◽  
Vertical Displacements ◽  
Regional Tectonic ◽  
Anomaly Map

Studies were made of total field aeromagnetic data over an area covering a section of the Appalachian belt in eastern Canada. This area is bounded by latitudes 45 °N and 47°40′ N and longitudes 62°30′ W and 67 °W. The residual magnetic values were filtered analytically in order to accentuate the effects of regional tectonic trends in the area. The second vertical derivative values were evaluated for outlining the contacts of magnetized geological formations with a reasonable degree of accuracy. Results of the analysis of the Bouguer anomaly map for the area seemed to correspond well with the tectonic trends indicated by the aeromagnetic data. Sixty-five anomalies were chosen from the residual and filtered maps to determine the following parameters of the causative bodies: (1) intensity of polarization; (2) direction-cosines of the polarization vector; and (3) depths to the top and bottom of the bodies.The picture of the pre-Carboniferous basement, as inferred from aeromagnetic data, is that of a valley and ridge configuration characterized by a series of subparallel, elongated basement blocks with relative vertical displacements. The basement blocks are bounded by major fault systems, known or inferred, mostly of pre-Carboniferous age. These blocks are aligned mostly in the direction of major tectonic trend in the area. The details of subsurface Basement topography are discussed on the basis of the results of interpretation of aeromagnetic data. Most interesting of all is a belt of high magnetic intensity running roughly in a NW–SE direction over the Gulf of St. Lawrence and Prince Edward Island. It has been suggested that this belt is caused by a pre-Taconic topographic high, or alternatively, by a pre-Carboniferous basement high bounded by fault zones subparallel with the fault system under the Cabot Strait.

X.—A Gravity Survey in Ayrshire and its Geological Interpretation

1966 ◽  
Vol 66 (10) ◽  
pp. 239-265 ◽  
Author(s):  
Adam C. McLean
Keyword(s):  
Gravity Field ◽  
Bouguer Anomaly ◽  
Gravity Survey ◽  
Normal Faults ◽  
Red Sandstone ◽  
Geological Interpretation ◽  
The North ◽  
Close Relationship ◽  
Lower Palaeozoic ◽  
Western Limb

SynopsisBouguer anomaly maps covering most of Ayrshire at a density of about one station per sq. km., show a close relationship between anomalies and the distribution of the Upper Palæozoic rocks in the area south of the Inch-gotrick Fault, but are less clearly interpreted to the north, where thick dense igneous masses are present.In central and south Ayrshire the gravity field may be largely interpreted in terms of the known density-contrasts at the interfaces separating Upper and Lower Old Red Sandstone, and Lower Old Red Sandstone and Lower Palæozoic rocks. The major structure, the Mauchline Basin, is reflected clearly in the largest anomaly, and there is evidence of a culmination of its south-western limb near Kirkoswald. The important N.E.–S.W. faults also give rise to large anomalies, which may be connected with the known geology. It is inferred that they moved as normal faults in Carboniferous times, and that the adjacent synclines are essentially sags associated with the fault displacements. There is geophysical evidence that both the Southern Upland and Kerse Loch Faults existed in Middle O.R.S. (proto-Armorican) times. It is concluded that a hypothesis of N.–S. Armorican stress is not valid in south Ayrshire.In north Ayrshire, many of the anomalies are best explained by changes of thickness of the Millstone Grit lavas and of the Clyde Plateau lavas, and by the presence of thick dolerite intrusions. Additional evidence is needed, however, before final conclusions may be drawn.

scholarly journals Bouguer Anomaly Field, northeastern British Columbia

1990 ◽  
Author(s):  
D A Seemann
Keyword(s):  
British Columbia ◽  
Bouguer Anomaly ◽  
Anomaly Field

scholarly journals High resolution Slovak Bouguer gravity anomaly map and its enhanced derivative transformations: new possibilities for interpretation of anomalous gravity fields

2017 ◽  
Vol 47 (2) ◽  
pp. 81-94 ◽  
Author(s):  
Roman Pašteka ◽  
Pavol Zahorec ◽  
David Kušnirák ◽  
Marián Bošanský ◽  
Juraj Papčo ◽  
...  
Keyword(s):  
Gravity Field ◽  
Slovak Republic ◽  
Bouguer Anomaly ◽  
Gradient Field ◽  
Horizontal Gradient ◽  
Lateral Direction ◽  
Geological Interpretation ◽  
Gravity Fields ◽  
Anomalous Gravity ◽  
Anomaly Map

AbstractThe paper deals with the revision and enrichment of the present gravimetric database of the Slovak Republic. The output of this process is a new version of the complete Bouguer anomaly (CBA) field on our territory. Thanks to the taking into account of more accurate terrain corrections, this field has significantly higher quality and higher resolution capabilities. The excellent features of this map will allow us to re-evaluate and improve the qualitative interpretation of the gravity field when researching the structural and tectonic geology of the Western Carpathian lithosphere. In the contribution we also analyse the field of the newCBAbased on the properties of various transformed fields – in particular the horizontal gradient, which by its local maximums defines important density boundaries in the lateral direction. All original and new transformed maps make a significant contribution to improving the geological interpretation of theCBAfield. Except for the horizontal gradient field, we are also interested in a new special transformation ofTDXAS, which excellently separates various detected anomalies of gravity field and improves their lateral delimitation.

Interpretation of the gravity anomaly field in the Noranda – Val d'Or region, Abitibi Greenstone Belt, Canadian Shield

1992 ◽  
Vol 29 (5) ◽  
pp. 962-971 ◽  
Author(s):  
Pierre Keating
Keyword(s):  
Apparent Density ◽  
Cross Sections ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Geological Interpretation ◽  
Vertical Derivative ◽  
Generalized Inversion ◽  
Density Map ◽  
Anomaly Map ◽  
First Vertical Derivative

Gravity data from the Noranda – Val d'Or region have been reprocessed: the Bouguer anomaly map, the first vertical derivative map, and an apparent density map have been used for geological interpretation of the gravity field in this region. It is found that variations in the Bouguer anomaly can be mainly explained by density structures located within the uppermost 5 km of the crust. The vertical derivative map helps to better locate some geological contacts, and the apparent density map allows the easy distinction between thin and thick batholiths. Generalized inversion was used to calculate density cross sections from the Bouguer anomaly values, and measured surface formation densities were used as constraints. Analysis of a detailed profile in the Rouyn–Noranda area shows that steep north-dipping reflectors observed in a seismic reflection survey are associated with a north-dipping density structure.

A geological interpretation of the Bouguer anomalies adjacent to the Churchill–Superior boundary in northern Manitoba

1968 ◽  
Vol 5 (3) ◽  
pp. 439-453 ◽  
Author(s):  
R. A. Gibb
Keyword(s):  
Bouguer Anomaly ◽  
Gravity Gradient ◽  
Southern Limit ◽  
Near Surface ◽  
Surface Mass ◽  
Geological Interpretation ◽  
Bouguer Anomalies ◽  
Mass Distributions ◽  
Gravity Effects ◽  
Anomaly Map

The Bouguer anomaly map of nothern Manitoba and part of northeastern Saskatchewan was updated by a gravity survey in 1965. Density determinations of some 2000 Precambrian rock samples provide a sound basis for interpretation of the Bouguer anomalies in terms of relatively near-surface mass distributions in the upper crust. In some parts of the area there is excellent correlation between the surface rocks, their densities, and the Bouguer anomalies. The Nelson River gravity high outlines a belt of dense granulites. To the northwest three gravity lows are interpreted as the gravity effects of granitic intrusions, of which one is exposed at Split Lake and the others are largely subjacent, although their presence is supported by the occurrence of numerous mappable stocks of granite within the gravity lows. The Nelson River gravity high is separated from these lows by a steep gravity gradient, which marks a boundary between rocks of predominantly different ages (Hudsonian and Kenoran) between latitudes 54 °N and 56 °N. Age determinations are consistent with an interpretation of the Pikwitonei subprovince as an inlier of Kenoran age within the Churchill Province. The main Churchill–Superior boundary may then be moved south to what is at present the southern limit of the Cross Lake subprovince, which is a return to approximately the position originally selected by M. E. Wilson.

The Bouguer anomaly field of the Notre Dame Bay area, Newfoundland

10.4095/8785 ◽  
1978 ◽  
Author(s):  
H G Miller ◽  
E R Deutsch
Keyword(s):  
Bouguer Anomaly ◽  
Anomaly Field ◽  
Bay Area

Optimal Density Determination of Bouguer Anomaly Using Fractal Analysis (Case of study: Charak area,IRAN)

2005 ◽  
Vol 1 (1) ◽  
pp. 21-24
Author(s):  
Hamid Reza Samadi
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Fractal Geometry ◽  
Host Rock ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Density Difference ◽  
Optimal Density

In exploration geophysics the main and initial aim is to determine density of under-research goals which have certain density difference with the host rock. Therefore, we state a method in this paper to determine the density of bouguer plate, the so-called variogram method based on fractal geometry. This method is based on minimizing surface roughness of bouguer anomaly. The fractal dimension of surface has been used as surface roughness of bouguer anomaly. Using this method, the optimal density of Charak area insouth of Hormozgan province can be determined which is 2/7 g/cfor the under-research area. This determined density has been used to correct and investigate its results about the isostasy of the studied area and results well-coincided with the geology of the area and dug exploratory holes in the text area

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