Minettes of the Glória Norte Monzonic Stock: evidence of post-orogenic ultrapotassic magmatism, with subduction signature, in the Sergipano Orogenic System

Authors

  • Milena Prado Fontes Universidade Federal de Sergipe – UFS, Programa de Pós-Graduação em Geociências e Análise de Bacias (PGAB)
  • Herbet Conceição Universidade Federal de Sergipe – UFS, Laboratório de Petrologia Aplicada à Pesquisa Mineral (LAPA).
  • Maria de Lourdes da Silva Rosa Universidade Federal de Sergipe – UFS, Laboratório de Petrologia Aplicada à Pesquisa Mineral (LAPA).
  • Vinicius Anselmo Carvalho Lisboa Universidade Federal de Sergipe – UFS, Laboratório de Petrologia Aplicada à Pesquisa Mineral (LAPA).

DOI:

https://doi.org/10.11606/issn.2316-9095.v18-133599

Keywords:

Lamprophyre, Monzonites, Petrography, Geochemistry.

Abstract

Lamprophyres occur as microgranular enclaves in the Glória Norte Monzonitic Stock (588 ± 5 Ma), located in the central part of the Macururé Domain, Sergipano Orogenic System, in the state of Sergipe, Brazil. These lamprophric enclaves were classified as minettes and occur concentrated in an area of approximately 1 km in diameter in the southeast region of the stock. The minettes have porphyritic, panidiomorphic textures with biotite phenocrystals, and fine granulation matrix. The mafic minerals present, in addition to the biotite, are diopside, augite, hornblende and titanite. Perthitic orthoclase, andesine, biotite, carbonate, apatite and zircon are also present in the matrix. The data of the major (K2O/Na2O >3, 6 > %MgO > 8, K2O > 3%), minor and traces elements (low values of Ti, Nb, Ta) indicate orogenic ultrapotassic magmatism. The ratio Th/Yb > 9.00 and 0.05 < Ta/Yb < 0.20 points to magma formed by melting of an enriched mantle. The information obtained in this study indicates that ultrapotassic basic magmas were present during the post-tectonic period in the Sergipano Orogenic System (SOS).

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Published

2018-03-01

Issue

Vol. 18 No. 1 (2018)

Section

Articles

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How to Cite

Fontes, M. P., Conceição, H., Rosa, M. de L. da S., & Lisboa, V. A. C. (2018). Minettes of the Glória Norte Monzonic Stock: evidence of post-orogenic ultrapotassic magmatism, with subduction signature, in the Sergipano Orogenic System. Geologia USP. Série Científica, 18(1), 51-66. https://doi.org/10.11606/issn.2316-9095.v18-133599