GEOLOGIA FOLHA SB.23-VC (Imperatriz) - seplan - Governo do ...

This work aimed to update the geological survey of sheet Imperatriz
(SB.23-V-C), previously done at scale 1:1.000.000 by RADAMBRASIL and partially
at scale 1:250.000 by Mineral Resources Prospection Company (CPRM) under
Brazil´s Basic Survey Programme (PLGB) and Grande Carajás. The survey was
based on previous work reviews and traditional methodology, which embraces satellite
imagery photo interpretation, field observations and lithological, structural and
geotechnic parameters description, ending up in a geological map and its technical
report. Sheet Imperatriz in the state of Tocantins is totally contained within the
Parnaiba´s Intracratônic Basin and gathering areas as of the Upper Triassic. During
the present survey seven stratigraphic units were identified and defined. The most
common type of rocks are sandstones and both yellow and red siltstone, with
occasional presence of volcanic basic rocks. Continental sedimentary environments
are common of arid climate with restricted sea representation. The formations mapped
in the area were Sambaíba, Mosquito, Corda, Codó and Itapecuru. Sediments of
the tertiary covers and recent alluvia complete the column. The stratigraphic units
are almost horizontal, showing little dumps/tilts, which originate slight dives. There
are evidences of falhas associated to NE-SW and NW-SE directions, specially in
the sediments of Itapecuru Formation.
Abstract