Point Bars in Ancient Fluvial Deposits: Examples in Geological Record of Rio Grande do Sul State, Brazil

Abstract

A point bar is one of the main architectural elements of a fluvial system, commonly described in several sedimentary basins all over the world. However, there are only few examples of this kind of macroform described in Brazilian sedimentary basins. In this paper, two point bars in ancient fluvial deposits outcropping in the Rio Grande do Sul State were described. The Point Bar 1 (PB1) is interpreted as lateral accretion deposits in a bed load channel of moderate to high sinuosity, whose depth was around 5 meters. The PB2 is associated to a mixed load channel, with high sinuosity and depth around 6 meters. Based on geometrical, textural and structural characteristics, differences in depositional and hydrodynamic conditions of the studied paleochannels deposits have been established.