A neoproterozoic age for the chromitite and gabbro of the Tapo Ultramafic Massif, Eastern Cordillera, Central Peru, and its tectonic implications

Tassinari, Colombo G. and Castroviejo Bolibar, Ricardo and Rodrigues, Jose F. and Acosta, Jorge and Pereira, Eurico (2011). A neoproterozoic age for the chromitite and gabbro of the Tapo Ultramafic Massif, Eastern Cordillera, Central Peru, and its tectonic implications. "Journal of South American Earth Sciences", v. 32 (n. 4); pp. 429-437. ISSN 0895-9811. https://doi.org/10.1016/j.jsames.2011.03.008.

Description

Title: A neoproterozoic age for the chromitite and gabbro of the Tapo Ultramafic Massif, Eastern Cordillera, Central Peru, and its tectonic implications
Author/s:
  • Tassinari, Colombo G.
  • Castroviejo Bolibar, Ricardo
  • Rodrigues, Jose F.
  • Acosta, Jorge
  • Pereira, Eurico
Item Type: Article
Título de Revista/Publicación: Journal of South American Earth Sciences
Date: December 2011
ISSN: 0895-9811
Volume: 32
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

The ultramafic-mafic rocks of the Tapo Complex are exposed in the Eastern Cordillera of the Central Peruvian Andes. This complex is composed of serpentinised peridotites and metabasites with some podiform chromitite lenses and chromite disseminations and overlies the sandstones, conglomerates, and tuffs of the Carboniferous Ambo Group. The metagabbros and amphibolites showa tholeiitic affiliation and a flat REE spider diagram, with a slight LREE depletion and a positive Eu anomaly suggesting magmatic accumulation of plagioclase, in an ocean ridge or ocean island environment. Sm-Nd isotopic analyses were performed on chromite as well as on whole rock from the gabbro. All samples yielded an Sm-Nd isochrone age of718 ± 47 Ma with an initial 143Nd/l44Nd of0.51213 ± 0.00005. The Nd (718 Ma) values calculated for both chromite and gabbro are in close agreement, around 8.0, implying that they were formed at the same time from the same mantelic magma source. Furthermore a K-Ar age on amphibole of 448 ± 26 Ma was obtained, interpreted as the cooling age of a younger orogenic event. These rocks represent slices of oceanic crust (from a dismembered ophiolitic complex), metamorphosed and later overthrust on upper Palaeozoic continental formations.

More information

Item ID: 10216
DC Identifier: http://oa.upm.es/10216/
OAI Identifier: oai:oa.upm.es:10216
DOI: 10.1016/j.jsames.2011.03.008
Official URL: http://www.journals.elsevier.com/journal-of-south-american-earth-sciences/
Deposited by: Biblioteca ETSI Minas y Energía
Deposited on: 03 Feb 2012 09:10
Last Modified: 20 Apr 2016 18:27
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