Foram reconhecidos diversos tipos de fragmentos juvenis na matriz das brechas de facies diatrema, incluindo armoured lapilli, frozen droplets e spinning droplets. Este trabalho descreve os spinning droplets e propoe um modelo para sua gerafao em diatremas. Palavras-chave: spinning droplets, kamafugito, diatrema, lapilli ABSTRACT Kamafugitic lavas, dykes and diatremes occur in the Aguas Emendadas Region, southern Goias, forming part of the Late-Cretaceous Rio Verde-Ipora Igneous Province. A variety of lapilli-sized juvenile fragments occurring in the matrix of diatreme-facies breccias were recognised. These include armoured lapilli, frozen droplets and spinning droplets. This work describes the spinning droplets and proposes a model for their formation in diatrene environments.
The Late-Cretaceous Alto Paranaíba Igneous Province (APIP) comprises a variety of ultrapotassic rock-types, including kimberlites, lamproites and large volumes of kamafugites, in addition to a number of carbonatite-bearing plutonic alkaline complexes. Phlogopite-picrites are ultramafic fine-grained rocks typically composed of olivine phenocrysts set in a groundmass of phlogopite, carbonate, perovskite, apatite and chromite. They occur as dyke swarms in the carbonatite complexes, but are also scattered throughout the Province. The phlogopite-picrites represent the peralkaline, ultrapotassic, carbonate-rich, silicate magmas parental to the carbonatite-bearing complexes, and have strong chemical affinity with kamafugites. Together with petrographic similarities observed between silicate rocks from the carbonatite complexes and xenoliths occurring in APIP kamafugites, this provides a strong link between kamafugitic and carbonatitic magmatism in the Province.
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