Giovanni Moreira , Marcia Ernesto , Angelo De Min , Andrea Marzoli , Fábio Braz Machado , Eleonora Maria Gouvea Vasconcellos , Giuliano Bellieni
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引用次数: 0
Abstract
The Penatecaua magmatism (∼201 Ma) is part of the Central Atlantic Magmatic Province (CAMP) and is represented by voluminous sills in the Amazonas Basin, north Brazil. The sills appear south of the Amazonas River, particularly in the Medicilândia, Placas, and Rurópolis cities. To the north of the river, near Monte Alegre and Alenquer, smaller sills and NNE-SSW dikes prevail. Paleomagnetic data from 28 sampling sites of sills and dikes from all areas gave consistent results of normal polarity. Despite the large area of occurrence, the VGPs show small dispersion, consistent with a very brief emplacement time, as indicated by the radiometric ages. However, some sites, mainly from Alenquer and the southern sills, gave anomalous directions that may represent the record of a transitional geomagnetic field. The calculated paleomagnetic pole includes former data from Guerreiro and Schult (1986) plotting at 260.1°E 77.5°S (N = 30; A95 = 3.8°; k = 48) and agrees with other high-quality CAMP poles for South America.
期刊介绍:
Launched in 1968 to fill the need for an international journal in the field of planetary physics, geodesy and geophysics, Physics of the Earth and Planetary Interiors has now grown to become important reading matter for all geophysicists. It is the only journal to be entirely devoted to the physical and chemical processes of planetary interiors.
Original research papers, review articles, short communications and book reviews are all published on a regular basis; and from time to time special issues of the journal are devoted to the publication of the proceedings of symposia and congresses which the editors feel will be of particular interest to the reader.