Geochemistry of serpentinites from the central portion of the Rio Piranhas-Seridó Domain, Borborema Province, Northeastern Brazil: Implications for genesis and geotectonic environment
Article Sidebar
Main Article Content
Abstract
Serpentinites from the central portion of the Rio Piranhas-Seridó Domain (RPSD), in the northeast portion of the Borborema Province (BP), occur in association with the Caicó Complex gneisses, paragnaisses/schists of the Seridó Group. Serpentinites, which were sampled in two localities near the city of São Tomé-RN, are melanocratic rocks, fine-grained, greenish in color and foliation consistent with the regional trend. The mineralogical composition is primarily composed of serpentine, which occurs as a replacement for the iron and magnesium minerals of the protolith, with chlorite, muscovite, tremolite, calcite-dolomite, quartz, and opaque minerals as accessory phases. Chemical analyzes show SiO2 values ranging from 35.72 to 43.48%, MgO> 28.88%, Fe2O3 between 7.08 and 11.29%, Al2O3 < 3.42% and very low TiO2, CaO, K2O and Na2O, suggesting an ultrabasic composition. Graphs obtained with the major elements ratios indicate olivine as the primary mineral, and despite the influence of metamorphic processes, the rock still retains the chemistry predominant in the protolith. The high magnesium content points to a komatiitic signature, implying in high temperature, high pressure and high degree of partial melting in the protolith genesis. Data acquired in this study corroborate the bibliography and suggest a compatible scenario for the studied serpentinites to be part of a greenstone belt.
Article Details
This work is licensed under a Creative Commons Attribution 4.0 International License.
The papers are published in the open access format, being freely available to any user, under a CC-BY Creative Commons license.
By submitting this manuscript for evaluation, the authors are aware of the CC-BY Creative Commons license. In the case of manuscript approval, the author responsible for the manuscript (corresponding author), hereinafter referred to as CEDENTE (ASSIGNOR), hereby assigns and transfers to CPRM-Serviço Geológico do Brasil, holder of the JGSB, free of charge, on his behalf and on behalf from all co-authors, the right of the first publication. This includes the rights of editing, publication, translation into another language and reproduction by any process, worldwide, today and in the future.
After the first publication by the JGSB, authors hold the copyright without restrictions and are allowed to disclose and distribute their work through personal website pages and institutional repositories.
At the same time, the ASSIGNOR declares that the content of the manuscript is of sole responsibility of the authors and that this content does not infringe the copyrights and/or other property rights of third parties, that is, that any contents of the manuscript and its attachments, if taken from other publications, are duly referenced and, when necessary, the permissions for publications of such contents were requested by the authors from the copyright holders; that the disclosure of images (if any) has been authorized and that it assumes full moral and/or patrimonial responsibility, due to its content, before third parties.