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Petrografia, química mineral e litoquímica de diques máficos cambrianos do extremo oriental do estado da Paraíba

2009; Sociedade Brasileira de Geologia; Volume: 39; Issue: 3 Linguagem: Inglês

10.25249/0375-7536.2009393580598

2177-4382

Vidyã Vieira de Almeida, Maria Helena Bezerra Maia de Hollanda,

Paleontology and Stratigraphy of Fossils

The Itabaiana mafic dike swarm (Paraíba State) is inserted in the Transversal Zone domain at eastern Borborema Province (NE Brazil). It comprises two dike sets of deci- to centimetric dimension in width, which are c. 40 km far from. Dikes are geochemically basalts to andesites, but dominantly including andesite basalts with sub-alkaline, tholeiitic affinity. As a whole, the mineralogical assembly is represented by labradorite, titano-augite and olivine (Fo76-84), which occur as fine-grained groundmass as well microfenocristals. Iddingsite and bowlingite are pervasive secondary mineral phases replacing olivine and pyroxene. Carbonate occurs filling vesicles, and is also a common mineral phase in the studied dikes. Minor and rare earth spectra are similar for all dikes, and are characterized by moderate, chondrite-related, enrichment in Rb, Ba, Th, K and light rare earth elements, and in minor extent in Zr, Hf and Ti. Differences in respect to (La/Yb)N ratios suggest small variation in partial melting rates from a common source that could be lithospheric mantle.