The stratigraphy of the Bushveld Complex; a reappraisal and the relocation of the Main Zone boundaries
1990; Geological Society of South Africa; Volume: 93; Issue: 2 Linguagem: Inglês
ISSN
1996-8590
Autores Tópico(s)Geological Studies and Exploration
ResumoThe zonal nomenclature of the Bushveld Complex, relegated to informal status by the South African Committee for Stratigraphy (1980), is reinstated and redefined using a hierarchy of zones, subzones, macro-units, units, and layers. The subdivision of the succession is based on unconformable relationships and petrological coherence in terms of petrography, mineralogy, and geochemistry. The lower and upper boundaries of the Main Zone are placed at the bases of the Merensky cyclic unit and the Pyroxenite marker, respectively. The succession between the Pyroxenite marker and the first appearance of magnetite is placed in the Upper Zone, which leaves the Main Zone with two subzones. The bases of the Merensky cyclic unit and the Pyroxenite marker both mark the position of major magma mixing events in the magma chamber with concomitant development of unconformable and transgressive relations to the previously deposited layered cumulates. The Merensky and Bastard cyclic units comprise the Transitional macro-unit of the Main Zone
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