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vol.48 issue2Morphology and stratigraphy of Serra Geral silicic lava flows in the northern segment of the Torres Trough, Paraná Igneous ProvinceLocal geological sections and regional stratigraphy based on physical geology and chemical stratigraphy of the Serra Geral Group from Araraquara to Avaré, SP author indexsubject indexarticles search
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Brazilian Journal of Geology

Print version ISSN 2317-4889On-line version ISSN 2317-4692

Abstract

MORAES, Lucia Castanheira de; SEER, Hildor José  and  MARQUES, Leila Soares. Geology, geochemistry and petrology of basalts from Paraná Continental Magmatic Province in the Araguari, Uberlândia, Uberaba and Sacramento regions, Minas Gerais state, Brazil. Braz. J. Geol. [online]. 2018, vol.48, n.2, pp.221-241.  Epub Feb 22, 2018. ISSN 2317-4889.  http://dx.doi.org/10.1590/2317-4889201820170091.

This study covers the region between the cities of Sacramento and Araguari/Uberlândia (Minas Gerais State, Brazil), where basalt flows from the Paraná Continental Magmatic Province outcrop. The investigated rocks present tholeiitic signature, with high titanium content, and are classified as Pitanga magma-type. The preserved basalt thickness is between 10 and 200 meters and individual flows do not exceed 15 meters thick. Flows were identified as sheet lobes, smaller and thinner flows units - stacked laterally and vertically forming compound lavas -, or frontal, centimetric lobes. The basalt flows show decimetric to metric intercalations of clastic sedimentary rock, with depositional characteristics that can vary from aeolian to lacustrine, and are important markers on prevailing environmental conditions. The plagioclases are dominantly labradorite and pyroxene is augite, whereas olivine can be hyalosiderite or hortonolite/ferrohortonolite. The behavior of the major, minor and trace elements is compatible with the presence of at least two parental magmas, which were subjected to fractional crystallization mainly of plagioclase, clinopyroxene, ilmenite and magnetite. There is a chemistry distinction between basalts from Sacramento to those from Araguari/Uberlândia region, the former one showing more evolved than the last one. The high (La/Lu)N values are indicative of partial melting of a garnet peridotite, while the Rare Earth Elements (REE) values are indicative of fractional crystallization.

Keywords : Paraná-Etendeka Province; Lithostratigraphy; Petrography; Lithochemistry; Mineral chemistry.

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