Paleomagnetismo de um Enxame de Diques Toleíticos de Idade Meso-cenozóicas, Localizados no Rio Grande do Norte
Abstract
Thirteen sites from I probably Lower Cretaceous tholeiitic dike swarm in Rio Grande do Norte (approx. 5.5oS, 36.8oWl have been sampled (128 samples). After the alternating field cleaning, their mean direction is D=186.60, l=+20.6o withα95 = 14.0, K = 12.9, N = 10. This yields a pole at 80.60S, 274.80E with A95 9.5 and K = 26.8, which for South America is nearer to the Upper Cretaceous poles than to the Lower Cretaceous poles. This may reflect an uncertainty in determination of the age of the dikes: although some existing radiometric determinations indicate ages of about 130 m.y., some authors attribute a younger age (Upper Cretaceous or Tertiary) to the dikes. Rock magnetic investigations showed that the magnetic phase in the tholeiitic rocks is mainly magnetite and maghemite with poor titanium content.
Full Text:
PDFReferences
ADE-HALL, J.M., WILSON, R.L. e SMITH, P.J. - 1964 - The petrology, Curie points and natural magnetizations of basic lavas. Geophys, J. R. Astron. Soe. 9: 323-336.
BEURLEN, K. - 1967 - Geologia da região de Mossoró. Editora Pongete, 137 pp.
GREEN, O.H. e RINGWOOD, A.E. - 1967 - The genesis of basaltic magmas. Contr. Mineral. and Petrol. 15: 103-190.
RODRIGUES, M.F.B. - 1967 - Rochas basálticas do Rio Grande do Norte e Paraíba IG/USP - tese de mestrado.
ROLF, P.A.A. - 1965 - O pico vulcânico do Cabuji. DNPM. Notas preliminares e estudos. 126: 26 pp.
PETERSEN, N., POHL, J., SCHMIDBAUER, E., SCHUL T, A. e SOFFEL, H.C. - 1979 - Typsierung der ls/T - Kuerven von Basalten. (não publicado).
SCHULT, A., HUSSAIN, A.G. e SOFFE L, H.C. - 1981 - Paleomagnetism of Upper Cretaceous volcanics and Nubian Sandstones of Wadi Natash, SE Egypt and implications for the polar wander path for Africa in the Mesozoic. J. Geophys. 50: 16-22.
SIAL, A.N. - 1975 - Petrologia e significado tectônico dos diabásios mesozóicos do Rio Grande do Norte e Paraíba. Atas do III Simpósio de Geologia: 207-221.
SIAL, A.N. - 1976 - The post-paleozoic volcanism of Northeast Brazil and its tectonic significance. An. Acad. Bras. Cienc. 48 Suplemento: 299-311.
DOI: http://dx.doi.org/10.22564/brjg.v1i2.2198
This work is licensed under a Creative Commons Attribution 4.0 International License.
a partir do v.37n.4 (2019) até o presente
v.15n.1 (1997) até v.37n.3 (2019)
Brazilian Journal of Geophysics - BrJG
Sociedade Brasileira de Geofísica - SBGf
Av. Rio Branco 156 sala 2509
Rio de Janeiro, RJ, Brazil
Phone/Fax: +55 21 2533-0064
E-mail: editor@sbgf.org.br
Since 2022, the BrJG publishes all content under Creative Commons CC BY license. All copyrights are reserved to authors.
