Journal of Petroleum Geology, Vol.8, No.1, pp.5-36, 1985

©Copyright 2000 Scientific Press, Ltd.

GEOLOGY AND EXPLORATION IN THE TAKUTU GRABEN OF GUYANAAND BRAZIL

F. D. Crawford*, C. E. Szelewski* and G. D. Alvey**

*Home Oil Company Ltd, 2300 Home Oil Tower, 324--8th Ave. S W, Calgary, Alberta, Canada T2P 2Z5.

**Bow Valley Explorations (UK) Ltd, Windsor House, 50 Victoria St., London SW1, England.

Abstract

The Takutu basin is a Mesozoic graben 280 km long and 40 km wide in northern Brazil and adjoining Guyana. It occupies an ancient PreCambrian shear zone within the heart of the Archean Guyana shield. Metavolcanic rocks and thick Proterozoic quartzites crop out north of the basin. Granitic rocks border the graben on the south and east. Mesozoic basalt forms a band of outcrop along the southern and eastern margins of the modern-day valley. The basin is filled with up to 5,400 m (18,000 ft) of Mesozoic sedimentary rocks, underlain by more than 1,700 m (5,600ft) of mafic volcanics of Jurassic and possibly older (i.e. Proterozoic) ages. Six regional unconformities were recognized within the basin fill.