About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande do Sul states. The remainder area is distributed in eastern Paraguay, northeastern Argentina and northern Uruguay. The shape of the depression is elliptical and covers an area of about 1,500,000 km2 (580,000 sq mi), of which 110,000 km2 are in Paraguay.[1] The basin developed during the Paleozoic and the Mesozoic with a sedimentary record comprising rocks from the Ordovician right up to the Cretaceous, thus spanning the time interval between 460 and 66 million years.[2] The maximum thickness of the infill reaches 7,000 m in its central area and is composed of sedimentary and igneous rocks.[3][4][5]