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| Titel |
Structural evolution of the La Paya pluton (Sierra de Cachi, NW Argentina): insights from the study of its magnetic fabric |
| VerfasserIn |
Aitor Aranguren, Fernando Hongn, Jose María Tubía, Nestor Vegas |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250145511
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| Publikation (Nr.) |
 EGU/EGU2017-9457.pdf |
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| Zusammenfassung |
| The La Paya granite is a pluton elongated in a northerly direction that spreads over 10 km2 in
the Sierra de Cachi (Eastern Cordillera of Salta, Andean belt, NW Argentina). This pluton
intrudes into high-temperature and low-pressure migmatites and schists. The metamorphic
evolution of the country rocks and the emplacement of the La Paya pluton took place in an
extensional tectonic setting during Ordovician times (Hongn et al., 2014). Subsequently, a
compressional tectonic event led to the formation of large E-verging folds with a
penetrative axial planar foliation. Due to the folding event, the current metamorphic
zonation is inverted and the metamorphic degree rises towards the west. The granite is
concordant with the metamorphic zonation and with the country rocks foliation. Schists
with biotite and andalucite (low to medium metamorphic grade) crop out in the
eastern border of the pluton and schists with cordierite (high grade) in the western
border.
The pluton is characterized by the coexistence of magmatic and solid-state structures. The
deformation is localized in shear bands concentrated in the pluton roof. Wide sectors of the
pluton core preserve medium- to coarse-grained equigranular textures of magmatic
origin on which we have collected samples from 28 sites in order to perform an
AMS study. Susceptibility values are very low, with k ranging between 19 and 67
x 10−6 SI. The obtained anisotropy values are in agreement with the magmatic
character of the analysed samples (Pj between 1,03-1,07). The magnetic foliations are
concordant with the contacts of the pluton. They show northwards trends and dips to the
west that are steeper close to the eastern pluton border. Magnetic lineations are
concentrated in two main maxima that define a great circle parallel to the pluton
elongation.
The parallelism between the magnetic fabrics from areas with magmatic structures and
the structures observed in domains with solid-state deformation points to a syn-kinematic
emplacement of the pluton during the development of the roof shear zone. The cartographic
data and the distribution of the magnetic lineations of the La Paya granite allows to
recognize an east-vergent antiform that folds the roof shear zone and the overall laminar
pluton.
Hongn, F.D., Tubía, J.M., Esteban, J.J., Aranguren, A., Vegas, N., Sergeev, S., Larionov,
A. and Basei, M. (2014). Journal of Iberian Geology 40 (2), 225-240.
DOI: 10.5209/rev_JIGE.2014.v40.n2.45303 |
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