Jardim do Seridó Suite: first example of Ediacaran peraluminous magmatism in the Rio Piranhas-Seridó Domain, Borborema Province, Northeast Brazil

Izaac Cabral Neto,Rogério Cavalcante,Vinícius José De Castro Paes ,Priscila Rezende Fernandes ,Vladimir Cruz De Medeiros ,Ioná De Abreu Cunha ,Elton Luiz Dantas ,Francisco Valdir Silveira ,Luana Duarte Santos ,Joseneusa Brilhante Rodrigues ,Ivana Conceição De Araújo Pinho

doi:10.29396/jgsb.2019.v2.n2.3

Izaac Cabral Neto, Rogério Cavalcante + Show 9 more

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https://doi.org/10.29396/jgsb.2019.v2.n2.3

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Abstract

Peraluminous granitoids were recently mapped in the Rio Piranhas-Serido Domain, the northeastportion of the Borborema Province. These bodies occur as stock and intrusive dikes in the metapelites of the Serido Formation, constituting the Jardim do Serido Suite. This suite has two facies. The first and most expressive facies consists of a medium-grained and whitish leucocratic monzogranite with muscovite, garnet, and biotite, while the second is represented by fine-grained and greyish leucocratic granodiorites with biotite, cropping out mainly on the edges of the main body. The thermobarometric conditions for the crystallization of the monzogranites were estimated between 2-5 kbar and 690-950 oC, whereas the lithochemical data indicate a syn-collisional peraluminous signature. Neoproterozoic garnet-biotite schist xenoliths of the Serido Formation are sometimes observed partially assimilated in the main body (stock). A U-Pb zircon age of 592 ± 2 Ma obtained in the main body is considered as the crystallization age of the Jardim do Serido Suite, corroborating the proposed existence of peraluminous magmas associated with the Brasiliano Orogenesis in the Rio Piranhas-Serido Domain. The chemical and petrographic data identified this suite as fertile to that it can generate dikes of rareelements-bearing pegmatites.

Highlights

The Rio Piranhas-Seridó Domain (DPS) of the Borborema Province is marked by significant Ediacaran-Cambrian magmatism that is represented by several batholiths, stocks, and dikes
Selway et al (2005) define fertile granite as a parental granite of pegmatite dikes mineralized to rare elements commonly presenting: (i) high silica content (> 69% SiO2); (ii) Al2O3/CaO + Na2O + K2O ratio> 1; (iii) muscovite, garnet, tourmaline, apatite, cordierite, andalusite and/or topaz; (iv) low Fe, Mg and Ca contents; (v) enrichment in rare elements (Li, Ta, Cs, Ga, Nb, Rb and/or Sn), generally greater than three times the average value of the upper continental crust (Table 4); (vi) K/Rb and K/Cs ratios lower
The monzogranite lithochemical data indicate that these rocks have a peraluminous signature, a fact that is corroborated by the muscovite and garnet paragenesis, while the tectonic setting diagrams suggest that these rocks are syn-collisional

Summary

Introduction

The Rio Piranhas-Seridó Domain (DPS) of the Borborema Province is marked by significant Ediacaran-Cambrian magmatism that is represented by several batholiths, stocks, and dikes. Cabral Neto et al and Souza et al (2018) identified and mapped leucocratic granitoids bearing muscovite, garnet and biotite in the region just south of Jardim do Seridó, in Rio Grande do Norte state. These intrusive bodies comprise the first records of peraluminous Ediacaran granite-granodiorites in the DPS, located in the same tectonic-geological context of important deposits and mineral occurrences (e.g., gold, tungsten, iron, Sn, Be, Li, Ta-Nb and Ta).

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