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| Titel |
Structure of the Rangel alkaline complex (Salta, NW Argentina) |
| VerfasserIn |
Nestor Vegas, Fernando Hongn, Jose María Tubía, Nilda Menegatti, Aitor Aranguren, Lidia Rodriguez-Méndez |
| 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 |
250148551
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| Publikation (Nr.) |
 EGU/EGU2017-12816.pdf |
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| Zusammenfassung |
| The alcaline complex of the Sierra de Rangel is a Cretaceous granitoid emplaced in the Puna
Region, at the province of Salta (NW Argentina). This granitoid spreads over 9 km2 and is
elongated following a NE-SW trend. The Rangel complex intrudes Quaternary sediments of
the Salinas Grandes salt flat towards the east and Ordovician quartzites and metapelites to the
west.
There are three main facies in the Rangel granitoid: the easternmost part of the intrusion
is composed by sienites that crop out in three hills isolated into the salt flat; the central part of
the stock made of alkaline granites and quartz-sienites; and the westernmost side
composed by alkaline granites. The available rubidium-strontium ages point out two
magmatic pulses: 134±1,6Ma for the granites and quartz-sienites and the sienites of the
central and eastern part and 122±1,5 Ma for the alkaline granites of the western
border.
The most common structure in the host quartzites and metapelites is N55oE-trending
schistosity that dips around 60o to the SE. This schistosity is parallel to the axial surface of
asymmetric folds with axes plunging to the east. The sharp western contact of the Rangel
complex with the host rocks display a N30oE strike and dips around 40o to the SE. This
contact is parallel to the intra-magmatic contact between the western and central facies and to
the NE-SW elongation of the granitoid.
The study of the magnetic fabrics carried on 52 sites of the Rangel complex outline the
presence of two sets of tabular intrusions: a main group of overlapping NE-trending sheets
that dip to the SE; and a minor group roughly perpendicular to the previous one. The
integration of the magnetic fabrics results and the structural data suggest that the former set of
intrusions are feeder dykes of the NE-trending sheeted intrusions. Moreover, the
radiometric data suggest that the oldest pulse corresponds to the upper part of the
granitoid. This fact would imply that the emplacement was controlled by roof lifting
mechanisms and that the younger magma pulses were stored at successively deeper levels. |
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