Geology and Geochronology of Ponte Nova Mafic-Ultramafic Massif (SP-MG)

Authors

  • Rogério Guitarrari Azzone Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Excelso Ruberti Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Gaston Eduardo Enrich Rojas Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Celso de Barros Gomes Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica

DOI:

https://doi.org/10.5327/Z1519-874x2009000200002

Keywords:

Alkaline magmatism, Serra do Mar Province, Mafic-Ultramafic cumulates, Geochronology

Abstract

The Ponte Nova alkaline mafic-ultramafic massif lies in the northern sector of the Serra do Mar Province, close to the eastern part of the Mantiqueira mountain range, SE Brazil. The massif is exposed in two different areas separated by basement rocks: the larger (~5.5 km²) is elliptical in shape and has a wide variety of rock types; the smaller (~1 km²) is irregular, petrographically less complex, and occurs south of the former. It is mainly composed of an alkaline gabbro association generated by successive magmatic pulses. The more abundant rocks are melagabbros and ultramafic cumulates (e.g., olivine clinopyroxenites and olivine-bearing melagabbros) found in the lower parts of the massif, together with porphyritic, equigranular and banded gabbros and monzogabbros in the upper partions. A magmatic breccia and a suite of dykes (lamprophyres to tephriphonolites) cut the intrusion. K/Ar geochronological data for the different rock types yielded an average Late Cretaceous age of 87.6 Ma which is comparable to the age of other alkaline intrusions present in the northern sector of the referred province. The difference in ages makes it difficult to sustain the hypothesis of a genetical association with the Trindade mantle plume

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Published

2009-06-01

Issue

Vol. 9 No. 2 (2009)

Section

Articles

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How to Cite

Azzone, R. G., Ruberti, E., Rojas, G. E. E., & Gomes, C. de B. (2009). Geology and Geochronology of Ponte Nova Mafic-Ultramafic Massif (SP-MG) . Geologia USP. Série Científica, 9(2), 23-46. https://doi.org/10.5327/Z1519-874x2009000200002