EVOLUÇÃO TECTÔNICA DO CRÁTON DO GUAPORÉ: COMPARADA COM A DO ESCUDO BÁLTICO

F. F. M. DE ALMEIDA

Resumo


A comparative study of the Precambrian tectonic differentiation of the Guaporé Cráton in South America, and the Baltic Shield in Europe, demonstrate that the major geologic events are synchronous and correlatables. The Transamazonian and Svecofennian-Karelian cycles are equivalent in age and geologic products, as well as the volcanic phenomena Uatumã and sub-Jotnian, which were both accompanied and followed by anorogenic granites between 1,700 and 1,500 m.y. The subsequent clastic Precambrian covers in both cratonic areas are associated with basic magmatism. The eastern part of the Guaporé Craton and the southwestern part of the Baltic Shield underwent tectonic regeneration in middle Upper Precambrian, where the Uruaçuan and Dalslandian geosynclines were formed. A tectono-magmatic reactivation at about 1,000 m.y., with production of anorogenic granites and acid to intermediate volcanism (Rondônia), as well as the Late Precambrian geosynclinal evolution at the eastern border of the Guaporé Cráton (Brasiliano) find no counterparts in the Baltic Shield.

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