sup 40 Ar- sup 39 Ar dating of the Beja gabbro: Timing of the accretion of southern Portugal
- Universite de Rennes I (France)
The {sup 40}Ar-{sup 39}Ar dating of the amphibole from the Beja gabbro (Southern Portugal) yields a plateau age at 336.4 {plus minus} 0.8 Ma (2{sigma} level). The corresponding calculated isotopic closure temperature is around 800C. The comparison of this temperature with the magnetic blocking temperature ({approximately}570C) allows an estimation of a probable thermoremanent acquisition age for the characteristic magnetization component of the Beja gabbro between 335Ma and 315Ma, assuming cooling rates between 10C/Ma and 100C/Ma. These results, combined wtih paleomagnetic results from the Beja gabbro and Late Paleozoic rocks from Southern Portugal (Perroud et al., 1985), suggest that the southermost part of Spain and Portugal was separated from Northern Iberia in Early Carboniferous times and was accreted to Europe during the Late Carboniferous.
- OSTI ID:
- 5667809
- Journal Information:
- Geophysical Research Letters (American Geophysical Union); (USA), Vol. 17:12; ISSN 0094-8276
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GEOLOGIC DEPOSITS
AGE ESTIMATION
PORTUGAL
ARGON 39
ARGON 40
CARBONIFEROUS PERIOD
GABBROS
ISOTOPE DATING
ISOTOPE RATIO
MAGNETIZATION
PALEOMAGNETISM
PLATE TECTONICS
ARGON ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DEVELOPING COUNTRIES
EUROPE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
IGNEOUS ROCKS
ISOTOPES
LIGHT NUCLEI
MAGNETISM
NUCLEI
PALEOZOIC ERA
PLUTONIC ROCKS
RADIOISOTOPES
ROCKS
STABLE ISOTOPES
TECTONICS
YEARS LIVING RADIOISOTOPES
580000* - Geosciences