Paleomagnetism of Middle Proterozoic (1.01 to 1.08 Ga) mafic dykes in southeastern Bahia State-São Francisco Craton, Brazil

Manoel S. D'Agrella-Filho, Igor G. Pacca, Paul R. Renne, Tullis C. Onstott, Wilson Teixeira

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

Paleomagnetic results from profuse Middle-Late Proterozoic mafic dyke swarms in southeastern Bahia State (São Francisco Craton) yield either an easterly direction with high upward inclination or a westerly direction with high downward inclination isolated during AF and/or thermal treatments. Thermal demagnetization behavior and thermochronologic and petrologic considerations indicate that these remanent components originated as primary TRM's. Four groups of directions were distinguished from dykes in spatially distinct areas: Ilheus normal polarity (D = 60.0°; I = -68.8°; α95 = 2.6°; N = 17), Olivença normal polarity (D = 82.4°; I = -71.0°; α95 = 5.1; N = 31), Itajú do Colônia (D = 99.0; I = -71.9 ; α95 = 5.9°; N = 23) and Olivença reversed polarity (D = 298.8°; I = 60.7°; α95 = 6.4°; N = 18), which yield paleomagnetic poles located at 100.4°E; 30.3°N (IN), 107.0°E; 16.1°N (ON), 111.0°E; 7.7°N (IC) and 280.2°E; 17.0°N (OR), respectively. These poles define an APW path for the São Francisco Craton between the time interval 1.01-1.08 Ga which is characterized by at least two polarity intervals.

Original languageEnglish (US)
Pages (from-to)332-348
Number of pages17
JournalEarth and Planetary Science Letters
Volume101
Issue number2-4
DOIs
StatePublished - Dec 1990

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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