Present address: IFP (Institut Français du Pétrole) – Divison Géologie-Géochimie, RB40, PB311, 92852 Rueil-Malmaison Cedex, France.
Sequence stratigraphic distribution of diagenetic alterations in coal-bearing, paralic sandstones: evidence from the Rio Bonito Formation (early Permian), southern Brazil
Version of Record online: 27 AUG 2003
Volume 50, Issue 5, pages 855–877, October 2003
How to Cite
Ketzer, J. M., Holz, M., Morad, S. and Al-Aasm, I. S. (2003), Sequence stratigraphic distribution of diagenetic alterations in coal-bearing, paralic sandstones: evidence from the Rio Bonito Formation (early Permian), southern Brazil. Sedimentology, 50: 855–877. doi: 10.1046/j.1365-3091.2003.00586.x
- Issue online: 27 AUG 2003
- Version of Record online: 27 AUG 2003
- Manuscriptreceived 1 August 2002; revision accepted 12 March 2003.
- sequence stratigraphy
Abstract Linking siliciclastic diagenesis to sequence stratigraphy allows a better understanding of the parameters controlling the spatial and temporal distribution of diagenetic alterations, and hence of reservoir quality. A study of the coal-bearing, alluvial, deltaic, estuarine and shallow-marine sandstones of the Rio Bonito Formation, early Permian, Paraná Basin (southern Brazil), reveals that the distribution of diagenetic alterations and of related reservoir quality evolution can be constrained within a sequence stratigraphic framework. Calcite, dolomite, siderite, kaolinite and pyrite cementation is consistently linked to sequence and parasequence boundaries, transgressive and maximum flooding surfaces and is systematically distributed within lowstand, transgressive and highstand systems tracts. Diagenesis of coal layers at parasequence boundaries has promoted the formation of stratabound calcite (detectable in resistivity wire line logs), concretionary pyrite and kaolinite and of silicate grain dissolution in sandstones located above and below these boundaries, particularly in the transgressive systems tract. Meteoric water diagenesis caused grain dissolution and the formation of kaolinite in sandstones below sequence boundaries and in lowstand systems tract sandstones. Carbonate bioclasts and low sedimentation rates in lag deposits at parasequence boundaries, transgressive and maximum flooding surfaces favoured the formation of grain-rimming siderite. The results of this study are relevant to the exploration of coal-bed methane and other coal-bearing reservoirs, where it is crucial to unravel and predict the distribution and quality of reservoirs and compartments.