ARCABOUÇO ESTRATIGRÁFICO NEÓGENO-QUATERNÁRIO DA PORÇÃO OESTE DA BACIA DO SOLIMÕES, AMAZÔNIA OCIDENTAL

Neogene-Quaternary stratigraphic framework of the western portion of the Solimões Basin, Western Amazon

Abstract

The stratigraphic context of the western Solimões Basin, in the border area between Brazil, Peru, and Colombia, was based on nine (9) wells (P1 to P9) from the Alto Solimões Carvão  Project. With the geological data (well logging) and geophysical data (Gamma Rays, Resistivity, and Spontaneous Potential) was elaborated the geological section A-A’, with SW-NE direction and about 400 km of extension, where was defined the thicknesses and boundaries of Solimões (Miocene-Pliocene) and Içá (Pliocene-Pleistocene) formations and the Quaternary Deposits. The Solimões Formation, exhibits lateral continuity in the P1 to P9 and 332 meters thickness, being comprised by pelites and sandstones interbedded, with limestone, lignites and subordinate conglomerates, that exhibit patterns of thinning, thickening and interdigitation. The Içá Formation occurs in the eastern portion of the section, being predominantly sandy, with rare intercalations of pelitos and lignites and thickness varying between 30 to 55m, covered by thin Quaternary deposits, composed by sand and mud (silt and clay), with a thickness of up to 16 meters. Geophysical profiles provided electrofacies patterns and, together with lithological data, allowed the individualization of stratigraphic limits and internal lithofacies, which were correlated in the analyzed profiles.