The inversion of the São José do Itaboraí paleocene basin (RJ) in a strike-slip regime

THE INVERSION OF THE SÃO JOSÉ DO ITABORAÍ PALEOCENE BASIN (RJ) IN A STRIKE-SLIP REGIME^*

A

NDRÉ L. FERRARI 1

^** and CLAUDIO RICCOMINI 2

^***

¹Universidade Federal Fluminense, Niterói, RJ.

² Instituto de Geociências, USP, São Paulo, SP.

Presented by ANTONIO C. ROCHA-CAMPOS

Drilling profiles from Companhia Nacional de Cimento Portland (CNPC) in the São José do Itaboraí Basin show separate domains with different contents of CaCO3 (> 60%, 30 - 60% and < 30%). This suggests that the basement contour of the basin was previously defined by CNPC on an economic basis, excluding the basal and peripheral layers with CaCO3 content < 30%. This reinterpretation reveals a different basement contour for the basin, especially in its western portion where it becomes 50% larger. To the south, the limit of the basin is the ENE São José Fault, which has a dextral offset coincident with the NW Transverse Fault. To the north, the new limit of the basin is defined by en echelon segments parallel to the São José Fault, which is offset by NW structures parallel to the Transverse Fault. One of these structures shows slickensides with low rake striations probably generated by a strike-slip regime. The folds and reverse faults parallel to the São José Fault (Rodrigues Francisco & Cunha 1978, An. Acad. Bras. Ci., 50: 381-416) reveal a basin inversion. The horizontal calcareous travertine veins that crosscut the vertical banded travertine layers and the gneissic basement near the São José Fault indicate that this inversion was, at least partially, synchronous with the hydrothermal activity in the basin. The basin inversion was associated with a counter-clockwise rotation of 1, from NE to NNW. The trace of the São José Fault suggests that this inversion was related to a change from a releasing to a restraining band in a sinistral strike-slip regime. Further, in the Pleistocene, the basin was affected by additional NW compression. (December 10, 1999)

^*

Supported by FAPESP, Proc. 97/12091-6.

^**

Scholarship holder, PICDT/CAPES.

^***

Scholarship holder, CNPq.

Publication Dates

• Publication in this collection
  05 Jan 2001
• Date of issue
  Dec 2000