Stratigraphic modeling of a transgressive barrier-lagoon in the Permian of Parana Basin, southern Brazil

Barrier-lagoon systems occur in most coastal regions worldwide. The sedimentary record of these environments is of scientific and economic relevance because important coal deposits are associated with them. We show the evolution of an ancient coal-bearing barrier-lagoon system in the subsurface on the southern Parana Basin, Brazil, from a stratigraphic modeling approach. The main objective is to simulate and understand the origin and evolution of this system controlled by relative sea level changes and sediment supply. Database comprises 75 logged boreholes that provided data about the main coal bed deposited in the back-barrier, as well as 19 cored and logged boreholes distributed along two stratigraphic sections, one parallel (NE-SW) and another perpendicular (NW-SE) to the paleocoastline. The dataset was uploaded in the Diffusive Oriented Normal and Inverse Simulation of Sedimentation (DIONISOS) software to establish basic parameters and simulate different scenarios. Described fades are interpreted as swamp, lagoon, sandy barrier and tide-influenced deposits, developed during a relative sea level rise of 16 m. The coal bearing succession was deposited during the transgressive system tract of fourth-order depositional sequence and included peat deposition in a swamp in the back-barrier, barrier breakup and landward migration. Results are of high relevance for understanding this paleoenvironment evolution and similar systems in intracratonic basins. This environment occurs both in ancient and recent coasts, and the present model supports the understanding of several barrier-lagoon systems with coal formation in the world.