Original paper

The Paredao kimberlite, Western Minas Gerais, Brazil: field relations, chemical data and host rocks

Sgarbi, Geraldo; Norberto Chaves Karfunkel, Joachimde; Albuquerque Sgarbi, Patrícia Barbosa Peregovich; Silva, Felipe; Pimenta Dias Pereira, Stefan; Moore, Dennis

Abstract

The Paredão kimberlite (Upper-Cretaceous) forms a circular-amoeboid depression of about 30 ha. It is emplaced in Neoproterozoic carbonates of the Bambuí Group (calcilutites, calcarenites and calcirudites of the Lagoa do Jacaré Formation) and shows a well-defined crater facies formed by pyroclastic deposits. The diatreme facies, not well observed, is deeply weathered, forming a homogeneous brown-greenish mass of clay material covered by soils. Field relations between the pipe and the host-rocks are marked by a significant difference in soil color and topography. Geological boundaries have been established through conventional geological mapping, enhanced by a radiometric prospecting using a total-count scintillometer. Furthermore, heavy-mineral prospecting was carried-out and the recovered kimberlite indicator minerals (pyrope, diopside, ilmenite and spinel) were analyzed. Chemical data placed the Paredão Kimberlite in the "non-diamondiferous" field.

Keywords

kimberliteupper cretaceouswestern minas geraisbrazilkimberlite pyroclastic facieskimberlite indicator mineralspyropeilmenite and diopside chemical datacarbonate host rocks of kimberlite