TY - JOUR
T1 - Paleomagnetism of Middle Proterozoic (1.01 to 1.08 Ga) mafic dykes in southeastern Bahia State-São Francisco Craton, Brazil
AU - D'Agrella-Filho, Manoel S.
AU - Pacca, Igor G.
AU - Renne, Paul R.
AU - Onstott, Tullis C.
AU - Teixeira, Wilson
N1 - Funding Information:
We thank Enzo M. Piccirillo, Giulliano Be-lliene, Maria Alba Taner de Oliveira, Cleuber Moraes, A. Jos6 Melfi and Mfircia Ernestof or the assistanced uring sample collection.T he funding for this researchw as providedb y CNPq, FAPESP and FINEP from Brazil and NSF (grants EAR-8451696a nd EAR-8805529)f rom the USA. We also thank three anonymous reviewers, whose commentsg reatly improved the quality of this manuscriptT. his work is contributionn umber20 of the IGCP-257, "Precambrian Mafic Dyke Swarms".
PY - 1990/12
Y1 - 1990/12
N2 - 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.
AB - 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.
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U2 - 10.1016/0012-821X(90)90164-S
DO - 10.1016/0012-821X(90)90164-S
M3 - Article
AN - SCOPUS:0025694253
SN - 0012-821X
VL - 101
SP - 332
EP - 348
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 2-4
ER -