Alkaline Rocks and Carbonatites of the World

Funded by HiTech AlkCarb - New geomodels to explore deeper for Hi-Tech critical raw materials in Alkaline rocks and Carbonatites

Lambari, Fazenda Do Toninho, Papira And Diorama

stripes

Occurrence number: 
025-00-046
Country: 
Brazil
Region: 
Goias
Location: 
Longitude: -51.25, Latitude: -16.12

A series of five sills and plugs of the Ipora Group are emplaced in sandstones of the Devonian Furnas Formation and comprise nine main outcrop areas. The northernmost group of Lambari covers about 70 km2 and is principally of basanite, which is a highly vesicular rock with phenocrysts of augite, hornblende and labradorite in a matrix of the same minerals, together with biotite (5-10%), opaques and accessory apatite, barkevikite, carbonate and analcime which may form euhedral crystals, possibly after leucite. Trachytes, with phenocrysts of alkali feldspar in a matrix of alkali feldspar, sodic plagioclase and a little quartz, form one mass in the Lambari sills and the 2 km diameter circular mass of Papira. The two sill outcrops of Fazenda do Toninho, both some 4 km2, are of an alkali pyroxenite composed of augite/Ti-augite (70%), biotite, a little olivine and accessory zeolite, plagioclase and opaques. Diorama is a 4x2 km sill principally of trachybasalt and 'andesite basalt'.

References: 
PENA, G.S. and FIGUEIREDO, A.J.A. 1975. Projeto Goiama II, relatorio final. Departamento Nacional da Producao Mineral. Companhia de Pesquisa de Recursos Minerais, 1: 121-61
Fig. 196 The Ipora Group of occurrences of alkaline intrusions of central Goias.
Location: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith