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Boletín de la Sociedad Geológica Mexicana Volumen 72, núm. 3, A280719, 2020 |
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Petrogenesis of the chromitite body from the Cerro Colorado ophiolite, Paraguaná Peninsula, Venezuela
Petrogénesis del cuerpo de cromitita de la ofiolita del Cerro Colorado, península de
Paraguaná, Venezuela
David J. Mendi1,2, José María González-Jiménez1,*, Joaquín Antonio Proenza3, Franco Urbani2,
Fernando Gervilla1,4
1 Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avenida. Fuentenueva s/n, 18002 Granada, Spain.
2 Universidad Central de Venezuela, Facultad de Ingeniería, Escuela de Geología, Minas y Geofísica, Caracas 1051, Venezuela.
3 Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona, 08028 Barcelona, Spain.
4 Instituto Andaluz de Ciencias de la Tierra (IACT), CSIC-UGR, Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain.
* Corresponding author: (J.M. González) This email address is being protected from spambots. You need JavaScript enabled to view it.
How to cite this article:
Mendi, D.J., González-Jiménez, J.M., Proenza, J.A., Urbani, F., Gervilla, F., 2020, Petrogenesis of the chromitite body from the Cerro Colorado ophiolite, Paraguaná Peninsula, Venezuela: Boletín de la Sociedad Geológica Mexicana, 72 (3), A280719. http://dx.doi.org/10.18268/BSGM2020v72n3a280719
Abstract
Ultramafic-mafic rocks of ophiolitic affinity crop out along the Venezuelan Caribbean region. They have been interpreted as remnants of the oceanic lithosphere of the Caribbean volcanic arc (135-70 Ma) as well as relicts of proto-Caribbean oceanic lithosphere (Upper Jurassic-Lower Cretaceous) related to Pangea’s break-up. The Cerro Colorado ophiolite, located in the Paraguaná Peninsula, together with the case of the Cordillera de la Costa in north-central Venezuela, are a unique case of these Venezuelan ophiolites containing chromitite bodies. However, the petrogenesis of such a mafic-ultramafic complex and associated chromite ore remains are unknown to date. To advance our understanding of chromite ores in the Caribbean region, the genesis of the Cerro Colorado chromitite body is challenged. The Cerro Colorado chromitite body is characterized by a low-Cr content [Cr# =Cr/ Cr+Al= 0.44-0.60] and a distribution of trace elements in chromite as is typical of high-Al chromitites found in the shallower portions of the petrological Moho Transition Zone of Mesozoic ophiolites. The calculated melts in equilibrium with chromite forming this high-Al chromitite body are back-arc basin basalts. These melts were extracted after ~20 % partial melting of moderately depleted peridotites, which resulted in the precipitation of high-Al chromitite relatively impoverished in PGE (≤ 100 ppb total PGE). A comparison of the geochemical signatures of minor and trace elements in chromite and bulk-PGE contents of the Cerro Colorado chromitite with those of other known chromitites in the peri-Caribbean ophiolites show certain similitude with those high-Al described in the Moa-Baracoa ophiolite in eastern Cuba. The obtained results allow us to suggest that the ultramafic rocks of the Cerro Colorado and the chromitite body associated with it are closely related to the formation of a back-arc basin developed between ca. 125-120 Ma in the rear of the Great Antilles Arc.
Keywords: Ophiolite, chromite deposit, platinum-group elements, Caribbean, Venezuela.
