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 Volume 34 - Issue 2-3 (1999) |
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Estructura, fábrica magnética y emplazamiento de los granitos de Brealito y La Paya, basamento del valle Calchaquí, Salta, Argentina
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F. D. HONGN, A. ARANGUREN, J. M. TUBIA y R. MON
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Abstract |
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The Brealito and La Paya granitoids are elliptical-shaped plutons with N-S elongation. They intrude into the Puncoviscana and La
Paya Formations, respectively. The internal structure of these plutons has been studied by using field structures and applying the
Anisotropy of the Magnetic Susceptibility (AMS). The magnetic fabric of the La Paya pluton reflects the orientation of biotite, the main
paramagnetic mineral in this granite (K between 1.9 and 6.7 x10-5SI). Instead, the magnetic behavior of the Brealito granite is more complex
since not only paramagnetic minerals, but also the ferromagnetic contribution (K between 22 and 466 x10-5SI) of magnetite crystals strongly
control the magnetic fabric of some samples. Total anisotropy values of the magnetic fabrics are coherent with the magmatic
nature of the analized samples. From the structural point of view, both plutons display similarities. These granites are lozenge-shaped
bodies concordant with the host rocks. Their planar fabrics are mainly NS-trending and West dipping, and magnetic lineations
plunge at low angles along the N-S direction.
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Keywords:
Structure. Magnetic fabric. Emplacement. La Paya and Brealito granites. Basement. NW Argentina.
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Full text (PDF) |
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