Low‐amplitude Aeromagnetic Anomalies in Southeastern Missouri

Allingham, John W.

doi:10.1190/1.1439390

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…Previous work shows that magnetic highs in Missouri can be correlated with enrichment of magnetite in felsic volcanic rocks and with the presence of mafic and therefore magnetite-rich intrusions [Ailingham, 1964;Phelan, 1969;Cordell, 1979]…”

Section: Information On the Distribution Of Precambrian Rock Types Inmentioning

confidence: 99%

Identification of a Precambrian Rift through Missouri by digital image processing of geophysical and geological data

Guinness¹,

Arvidson²,

Strebeck³

et al. 1982

J. Geophys. Res.

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Digital free air and Bouguer gravity anomaly images have been constructed from approximately 287,000 station readings for the region bordered by 25ø--49øN latitude and 80ø-110øW longitude. The technique used to interpolate between station locations was based on a two-dimensional spatial filter, where the average of the anomaly values located within the filter area was computed. The images contain as many as 256 contours (values in byte variable), so that subtle anomaly patterns can be identified and traced with much greater certainty than on most contour maps. A newly discovered feature in the midcontinent is a gravity low that begins at a break in the midcontinent gravity high in SE Nebraska, extends across Missouri in a NW-SE direction, and intersects the Mississippi Valley graben to form the Pascola arch. The anomaly varies from 120 to 160 km in width, extends about 700 km, and is best expressed in southern Missouri, where it has a Bouguer amplitude of approximately -34 mGal.The magnitude of the anomaly cannot be explained on the basis of a thickened section of Paleozoic sedimentary rock. The gravity data and the sparse seismic refraction data for the region are consistent with an increased crustal thickness beneath the gravity low. Some of the discrete positive magnetic anomalies in Missouri are located along the borders of the gravity low. Digitally enhanced thermal infrared images from the Heat Capacity Mapping Mission show a distinct alignment of linear struqtures with the gravity feature. The linear features in some cases correspond to mapped high-angle normal faults, to drape folds over relief within the Precambrian basement, and in some cases to extensions of mapped structures. The gravity anomaly also cuts across the major Precambrian boundary in SE Missouri, marking the change from older, sheared granites and metasedimentary rocks to younger granites and rhyolites. Given the cumulative evidence, the gravity anomaly is probably the present expression of a failed arm of a rifting event, perhaps one associated with the spreading that led to or preceded formation of the granite and rhyolite terrain of southern Missouri. basement rocks of southern Missouri and the locations and genesis of ore deposits. The area is a well-known lead mining district, where Mississippi Valley type Pb-Zn-Cu ores have accumulated in Cambrian carbonate rocks associated with stromatolitic reef and back-reef facies [Gerdemann and Meyers, 1972]. The location of these facies was controlled by the location of the shoreline, which was in turn controlled by t.he pattern of faulting of the Precambrian basement [Grundmann, 1977; Sweeney et al., 1977; Evans, 1977; Paarlberg and Evans, 1977; Mouat and Clendenin, 1977]. In addition, iron ores of magmatic origin can be found in the Precambrian basement rocks along fracture zones [Kisvarsanyi, 1976]. Structural studies of basement rocks in southern Missouri have been pursued for a considerable amount of time [see Kisvarsanyi and Kisvarsanyi, 1976], and a significant amount of information has ...

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Section: Information On the Distribution Of Precambrian Rock Types Inmentioning

confidence: 99%

Identification of a Precambrian Rift through Missouri by digital image processing of geophysical and geological data

Guinness¹,

Arvidson²,

Strebeck³

et al. 1982

J. Geophys. Res.

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The historical development of the magnetic method in exploration

et al. 2005

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The magnetic method, perhaps the oldest of geophysical exploration techniques, blossomed after the advent of airborne surveys in World War II. With improvements in instrumentation, navigation, and platform compensation, it is now possible to map the entire crustal section at a variety of scales, from strongly magnetic basement at regional scale to weakly magnetic sedimentary contacts at local scale. Methods of data filtering, display, and interpretation have also advanced, especially with the availability of low-cost, high-performance personal computers and color raster graphics. The magnetic method is the primary exploration tool in the search for minerals. In other arenas, the magnetic method has evolved from its sole use for mapping basement structure to include a wide range of new applications, such as locating intrasedimentary faults, defining subtle lithologic contacts, mapping salt domes in weakly magnetic sediments, and better defining targets through 3D inversion. These new applications have increased the method's utility in all realms of exploration — in the search for minerals, oil and gas, geothermal resources, and groundwater, and for a variety of other purposes such as natural hazards assessment, mapping impact structures, and engineering and environmental studies.

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9. Magnetic Exploration Methods

Nabighian¹,

Grauch²,

Hansen³

et al. 2010

Geophysics Today

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The magnetic method, perhaps the oldest of geophysical exploration techniques, blossomed after the advent of airborne surveys in World War II. With improvements in instrumentation, navigation, and platform compensation, it is now possible to map the entire crustal section at a variety of scales, from strongly magnetic basement at regional scale to weakly magnetic sedimentary contacts at local scale. Methods of data filtering, display, and interpretation have also advanced, especially with the availability of low-cost, high-performance personal computers and color raster graphics. The magnetic method is the primary explo-ration tool in the search for minerals. In other arenas, the magnetic method has evolved from its sole use for mapping basement structure to include a wide range of new applications, such as locating intrasedimentary faults, defining subtle lithologic contacts, mapping salt domes in weakly magnetic sediments, and better defining targets through 3D inversion. These new applications have increased the method's utility in all realms of exploration -in the search for minerals, oil and gas, geothermal resources, and groundwater, and for a variety of other purposes such as natural hazards assessment, mapping impact structures, and engineering and environmental studies.

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Low‐amplitude Aeromagnetic Anomalies in Southeastern Missouri

Cited by 3 publications

References 4 publications

Identification of a Precambrian Rift through Missouri by digital image processing of geophysical and geological data

Identification of a Precambrian Rift through Missouri by digital image processing of geophysical and geological data

The historical development of the magnetic method in exploration

9. Magnetic Exploration Methods

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