Geología de las ultramafitas pre-andinas de Tapo y Acobamba, Tarma, en la Cordillera Oriental de Perú

Castroviejo Bolibar, Ricardo and Rodrigues, Jose F. and Acosta, Jorge and Pereira, Eurico and Romero, Darwin and Quispe, Jorge and Espí Rodríguez, José Antonio (2009). Geología de las ultramafitas pre-andinas de Tapo y Acobamba, Tarma, en la Cordillera Oriental de Perú. "Geogaceta" (n. 46); pp. 7-10. ISSN 0213-683X.

Description

Title: Geología de las ultramafitas pre-andinas de Tapo y Acobamba, Tarma, en la Cordillera Oriental de Perú
Author/s:
  • Castroviejo Bolibar, Ricardo
  • Rodrigues, Jose F.
  • Acosta, Jorge
  • Pereira, Eurico
  • Romero, Darwin
  • Quispe, Jorge
  • Espí Rodríguez, José Antonio
Item Type: Article
Título de Revista/Publicación: Geogaceta
Date: May 2009
ISSN: 0213-683X
Subjects:
Faculty: E.T.S.I. Minas (UPM)
Department: Ingeniería Geológica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

Ultramafic rocks occur scattered along a 300 km long NNW-SSE trending belt, parallel to the central Peruvian Andes in the Cordillera Oriental, from Tarma (Junín Dept.) to Huancapallac and Tingo María (Huánuco Dept.). The Tarma occurrences (Tapo and Acobamba) are dealt with here, as the first step of a broader research. The Tapo massif comprises strongly tectonised serpentinites with scarce peridotitic relics, amphibolites and podiform chromitites. It was overthrust on early Carboniferous metasedimentary rocks of the Andean basement (Ambo Group), and it shows evidences of a pre-Andean deformational history, not observed in the Ambo Group; the basal thrust plane is folded by the Andean tectonics. The two smaller Acobamba occurrences are also allochtonous and show similar tectonic features. Major and trace element composition of amphibolites point to a tholeiitic basalt (to picrobasalt) protolith, compatible with an ocean-ridge or ocean-island environment. Small podiform chromitite lenses and chromite disseminations also occur; they are strongly deformed, metamorphosed and overprinted by hydrothermal alteration related to deformation, and were the subject of small scale mining. The ores comprise mainly chromite, ferritchromite, spinel, magnetite, ilmenite and scarce sulphides, as well as the secondary minerals stichtite and nimite. Results of this work exclude current interpretations of the Tarma ultramafites as autochtonous igneous intrusives, and point to a new interpretation for their emplacement.

More information

Item ID: 11289
DC Identifier: http://oa.upm.es/11289/
OAI Identifier: oai:oa.upm.es:11289
Official URL: http://www.sociedadgeologica.es/publicaciones_geogaceta.html
Deposited by: Biblioteca ETSI Minas y Energía
Deposited on: 02 Jul 2012 09:49
Last Modified: 20 Apr 2016 19:24
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