U.S. National Magnetic Anomaly Survey Specifications Workshop Report

Geophysics ◽  
1979 ◽  
Vol 44 (5) ◽  
pp. 991-992
Author(s):  
William J. Hinze
Keyword(s):  
Magnetic Anomaly ◽  
North American ◽  
Executive Committee ◽  
Ad Hoc ◽  
Magnetic Data ◽  
Aeromagnetic Data ◽  
Workshop Report ◽  
The North ◽  
Anomaly Map ◽  
The U.S

The National Magnetic Anomaly Map (NMAM) Committee, which was formed as an ad hoc committee in 1975 by the SEG Executive Committee, has recommended a multistage program for improving the aeromagnetic data of the U.S. On behalf of the geoscience community, the committee and the U.S. Geological Survey are currently engaged in the preparation of a photo‐composite map of the U.S. derived from publicly available data plus regional magnetic data contributed from the private sector. This map is at present being compiled and is to be pulished by the U.S.G.S. at a scale of [Formula: see text]. Eventually, utilizing this map, the committee plans to assist in the preparation of a North American magnetic anomaly map to supplement the North American tectonic map and the proposed continental gravity anomaly map.

North American Gravity and Magnetic Anomaly Workshops

Geophysics ◽  
1981 ◽  
Vol 46 (11) ◽  
pp. 1611-1617
Author(s):  
W. J. Hinze ◽  
N. W. O’Hara ◽  
M. S. Reford ◽  
J. G. Tanner
Keyword(s):  
Gravity Anomaly ◽  
Magnetic Anomaly ◽  
North American ◽  
North American Continent ◽  
The North ◽  
Terrain Effects ◽  
Gravity And Magnetic ◽  
Anomaly Map ◽  
Map Series ◽  
Gravity And Magnetic Anomaly

The North American Gravity and Magnetic Anomaly Map Workshops, realizing the importance of regional gravity and magnetic anomalies to investigating the structure and composition of the earth, enthusiastically support the preparation of North American gravity and magnetic anomaly maps. Sufficient magnetic and gravity anomaly data are available over the North American continent, the Caribbean, and adjacent marine areas to produce geologically meaningful maps. These maps will be published within the decade at a scale of 1:5 million on the same map base being used by a variety of organizations to produce other geologic/geochemical/geophysical maps in cooperation with the Geological Society of America’s Centennial Map Series. The anomaly maps will be published in color with transparent overlays also available. The gravity anomaly map will be contoured at a 10 mgal interval using Bouguer anomalies onshore corrected wherever possible and necessary for terrain effects and free‐air anomalies offshore. Existing or soon to be completed magnetic and gravity anomaly maps of Canada, the U.S., and Mexico will provide the nuclei for preparing the North American maps. Programs for producing these maps in a timely manner are organized based upon a series of committees and the cooperation of agencies of the involved North American nations.

Limitations of the long‐wavelength components of the North American magnetic anomaly map

Geophysics ◽  
1990 ◽  
Vol 55 (12) ◽  
pp. 1577-1588 ◽  
Author(s):  
J. Arkani‐Hamed ◽  
W. J. Hinze
Keyword(s):  
Magnetic Anomaly ◽  
North American ◽  
Data Set ◽  
Long Wavelength ◽  
Related Data ◽  
The North ◽  
North American Data ◽  
Crustal Magnetization ◽  
Anomaly Map ◽  
Lateral Variations

The magnetic anomaly map of North America and its related data set provide the opportunity not only to view the obvious short‐wavelength anomalies (<300 km) in a continental context, but to isolate and analyze the longer wavelength anomalies. However, care must be used in analyzing the longer wavelengths because of the effects of noncrustal sources on these anomalies. Inversion of the anomalies into lateral variations of crustal magnetization suggests that the long‐wavelength anomalies (>2600 km) are strongly affected by core field components that have not been completely removed from the North American data set. Furthermore, the piecewise matching of the magnetic anomalies of adjacent survey areas in the map compilation has contaminated the intermediate wavelength anomalies (300–2600 km).

Insights into the Red Sea area from magnetic and gravity analysis

2021 ◽  
Author(s):  
Ran Issachar ◽  
Jörg Ebbing ◽  
Dilixiati Yixiati ◽  
Nils Holzrichter
Keyword(s):  
Magnetic Anomaly ◽  
Red Sea ◽  
Magnetic Measurements ◽  
Magnetic Data ◽  
Lithosphere Structure ◽  
The North ◽  
Southern Central ◽  
Anomaly Map ◽  
Sea Floor Spreading ◽  
Sea Area

&lt;p&gt;We explore the lithosphere structure of the Red Sea using gravity and magnetic data.&lt;/p&gt;&lt;p&gt;We re-processed marine data form past surveys conducted during the 70&amp;#8217;s and the 80&amp;#8217;s, available at the NGDC database. By correcting the magnetic measurements according to the DGRF (definitive magnetic reference field), leveling and replacing the long wavelengths with satellite data (LCS1 model) we managed to generate a consistent magnetic anomaly map for the entire length of the Red Sea that is composed of 10 different surveys and contain overs 100,000 measuring points. The magnetic anomaly map highlights structural differences between the southern, central and northern parts of the Red Sea.&lt;/p&gt;&lt;p&gt;Using forward gravity approach, constrains from seismic, wells and petrophysical data, and by integrating insights from magnetic analysis, we define the lithospheric model of the Red Sea to address key questions regarding rifting, sea floor spreading and transition processes.&amp;#160; For example, the southern parts of the Red Sea are characterized by shallow and wide asthenosphere upwelling, while in the axial trough lithosphere is thin with thicknesses of less than 15 km. The lithosphere thickness increase asymmetrically towards the rift shoulders. In general, the lithosphere is thicker on the eastern sides than on the western sides. In the central parts of the Red Sea, the lithosphere structure is not significantly different from the southern parts, however, asthenosphere upwelling is slightly narrower. In northern parts of the Red Sea asthenosphere upwelling significantly narrows and focused mainly beneath the axial trough and the lithosphere is thicker. This architecture reflects the currently transition from continental rifting (in the north) to oceanic seafloor spreading (in the south) in the Red Sea.&lt;/p&gt;

Too Close for Comfort: Canada, the U.S. Civil Rights Movement, and the North American Colo(u)r Line

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Asa McKercher
Keyword(s):  
Civil Rights ◽  
Civil Rights Movement ◽  
North American ◽  
The North ◽  
The U.S

Too Close for Comfort: Canada, the U.S. Civil Rights Movement, and the North American Colo(u)r Line

scholarly journals PEMODELAN BAWAH PERMUKAAN MANIFESTASI MINERAL DENGAN METODE GEOMAGNETIK DAERAH PACITAN JAWA TIMUR

KURVATEK ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 25-33
Author(s):  
Fatimah Fatimah
Keyword(s):  
Image Data ◽  
Geological Structure ◽  
Magnetic Data ◽  
Magnetic Intensity ◽  
Magmatic Arc ◽  
The North ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Extensional Structure ◽  
Anomaly Map

Tulakan Subdistrict, Pacitan Regency, East Java Province. This area is part of the Southern Mountain Zone of East Java, which is the Sunda-Banda magmatic arc of Oligo-Miocene age, where there are alterations and indications of valuable ore minerals. Field magnetic data is taken in an area of 1 x 1 km, with the looping method on the grid trajectory within 200 x 100 m. Then, magnetic data correction and data processing were carried out with Oasis Montaj. From the magnetic anomaly map, the value of high magnetic intensity in the southern part is fresh (intrusive) andesit-dasitic rock as host rock which causes alteration, in the middle has a low magnetic intensity value which is in the direction of the relatively NE-SW river direction, whereas in the north with high intensity is fresh andesite lava. From the image data, it can be seen that the straightness pattern of the geological structure which is dominated by the extensional structure with the direction of NE-SW and E-W is the main trap of epithermal veins carrying ore mineralization mainly Cu, Pb in the study area.

Changing the U.S. Sugar Program into a Standard Crop Program: Consequences under the North American Free Trade Agreement and Doha

2008 ◽  
Vol 30 (1) ◽  
pp. 82-102 ◽  
Author(s):  
David Abler ◽  
John C. Beghin ◽  
David Blandford ◽  
Amani Elobeid
Keyword(s):  
Free Trade ◽  
North American ◽  
Free Trade Agreement ◽  
Trade Agreement ◽  
The North ◽  
The U.S

scholarly journals Trade Creation and Trade Diversion in the North American Free Trade Agreement: The Case of the Agricultural Sector

2007 ◽  
Vol 39 (1) ◽  
pp. 121-134 ◽  
Author(s):  
Dwi Susanto ◽  
C. Parr Rosson ◽  
Flynn J. Adcock
Keyword(s):  
Free Trade ◽  
North American ◽  
Free Trade Agreement ◽  
Agricultural Sector ◽  
Trade Agreement ◽  
Trade Diversion ◽  
The North ◽  
Tariff Rates ◽  
Agricultural Imports ◽  
The U.S

This paper examines the effect of the U.S.-Mexico trade agreement under the North American Free Trade Agreement (NAFTA). The results suggest that U.S. agricultural imports from Mexico have been responsive to tariff rate reductions applied to Mexican products. A one percentage point decrease in tariff rates is associated with an increase in U.S. agricultural imports from Mexico by 5.31% in the first 6 years of NAFTA and by 2.62% in the last 6 years of NAFTA. U.S. imports from Mexico have also been attributable to the pre-NAFTA tariff rates. Overall, the results indicate that the U.S-Mexico trade agreement under NAFTA has been trade creating rather than trade diverting.

Neoliberalism and Counterinsurgency

Colombia ◽  
2020 ◽  
Author(s):  
Richard D. Mahoney
Keyword(s):  
United States ◽  
Free Trade ◽  
Latin American ◽  
North American ◽  
Free Trade Agreement ◽  
Trade Agreement ◽  
The United States ◽  
The North ◽  
Trade Promotion ◽  
The U.S

How did the U.S.-Colombia free trade agreement come about? The officially named “U.S.-Colombia Trade Promotion Agreement” was the stepchild of a rancorous hemispheric divorce between the United States and five Latin American governments over the proposal to extend the North American Free Trade Agreement...

scholarly journals Effect of Liberalized U.S.-Mexico Dry Onion Trade: A Spatial and Intertemporal Equilibrium Analysis

1996 ◽  
Vol 28 (1) ◽  
pp. 135-147 ◽  
Author(s):  
Stephen Fuller ◽  
Melanie Gillis ◽  
Houshmand A. Ziari
Keyword(s):  
Free Trade ◽  
North American ◽  
Equilibrium Model ◽  
Equilibrium Analysis ◽  
Farm Level ◽  
The North ◽  
Storage Methods ◽  
Intertemporal Equilibrium ◽  
The Impact ◽  
The U.S

AbstractA spatial, intertemporal equilibrium model of the North American dry onion economy is constructed to analyze the impact of liberalized U.S.-Mexico trade. In a free-trade environment, exports of Mexican onions to the U.S. are projected to increase about 50%, while Mexico's share of the U.S. market increases from 8.7 to 12.8%. Farm-level prices in the U.S. are projected to decline 8.9%, while production declines 2.4%. The effect of free trade on U.S. producers is disproportional across regions. Northwest storage onion producers experience the greatest decline in production; however, analysis suggests that improved storage methods may offset a portion of the unfavorable impacts of liberalized trade on these producers. In spite of the unfavorable impact of free trade on U.S. dry onion producers, the industry would not be economically devastated.

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