Review of the areal extent and the volume of the Serra Geral Formation, Paraná Basin, South America

Abstract

In the discussion of the origin of continental flood basalt provinces, one of the most important constraints is the volume of the mobilized magma. Concerning the Serra Geral Formation in the Paraná Basin (South America), most authors cite an actual areal extent of 1,200,000 km² and a volume of approximately 800,000 km³ . The same volume is often used for the Paraná-Etendeka Continental Flood Basalt Province, from which the Serra Geral Formation is the major part. We investigated the precision of these numbers through a complete historical review of their origin. We found that the areal extent cut off of 1,200,000 km² is only an estimate made in 1934, and that the volume cut off of 800,000 km³ aroused using this areal extent estimate and an estimate of a mean thickness of 650 m of the flows made in 1966. Using a new map, we found that the area covered by the volcanic rocks in the Paraná Basin is of only 917,000 km² (+- 15,000 km² ). With isopach maps of 1987 and 1990, we calculated the volume of the extrusive rocks to be of at least 450,000 km³ and of the intrusive sill-type bodies to be of at least 112,000 km³ . With these estimates, the volume of the Serra Geral Formation should be considered to be of more than 600,000 km³ . For the Paraná-Etendeka Continental Flood Basalt Province as a whole, a volume of at least 1,700,000 km³ should be considered.