Abstract
The Serra da Graciosa region includes important occurrences of granites and syenites of the Graciosa A-type Province (formerly Serra do Mar Suite), southern Brazil. Using fieldwork, petrography, and remote sensing imagery, we characterize the geology of the plutons in the region. Five individual plutons were recognized. Two correspond to the previously defined Marumbi and Anhangava Plutons. We divide the former "Graciosa Pluton" into three new plutons: Capivari, Órgãos, and Farinha Seca. The plutons are elliptical with northeast-southwest orientation. Two petrographic associations can be recognized: an alkaline association that includes peralkaline and metaluminous hypersolvus alkalifeldspar granites and syenites (Anhangava, Farinha Seca, Órgãos), and an aluminous association composed of metaluminous and weakly peraluminous subsolvus granites (Capivari, Órgãos, Anhangava, Marumbi). Occurrences of each association are limited to one individual pluton or to portions of a pluton, and the age relationships are not well established. Monzodioritic rocks are found marginal to the Órgãos and Farinha Seca Plutons, and interaction with silicic magmas locally produced hybrid quartz syenites (Farinha Seca Pluton). Geothermobarometry indicates emplacement at shallow crustal levels (P = 2 ± 0.6 kbar), and crystallization temperatures within the interval 900-700ºC for the granitic and syenitic rocks, and 1000-750ºC for the monzodioritic rocks.
Highlights
The Serra da Graciosa region, eastern Paraná State, includes some of the most expressive occurrences of granites and syenites of a large A-type province in southern Brazil, originally referred to as the Serra do Mar Suite (Kaul 1984).This province includes several granitic and syenitic plutons characterized by the coexistence of alkaline and aluminous A-type petrographic associations
The region in which we focus our attention in this work, here denominated the Serra da Graciosa region, includes a series of mountain ranges (Figure 3) that combined correspond to the Serra do Mar in this area
The combination of fieldwork, remote sensing and general petrography led to the definition of five independent plutons in the Serra da Graciosa region
Summary
The Serra da Graciosa region, eastern Paraná State, includes some of the most expressive occurrences of granites and syenites of a large A-type province in southern Brazil, originally referred to as the Serra do Mar Suite (Kaul 1984) This province includes several granitic and syenitic plutons characterized by the coexistence of alkaline and aluminous A-type petrographic associations. An association consisting of hypersolvus alkali-feldspar syenites and alkali-feldspar granites, metaluminous to peralkaline in character, is typical of and is distributed throughout the Graciosa Province (Kaul 1997) They are characteristically leucocratic, medium-grained, equigranular rocks, and occupy the totality of the Corupá Pluton (Garin et al 2003), as well as significant portions of the Morro Redondo Complex (Góis 1995) and Anhangava Pluton (Gualda 2001). The distribution of distinct varieties, as well as the field and genetic relations between them, are still very poorly constrained
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