Meandering Stream Deposits From the Tertiary of the Southern Pyrenees

Abstract Three examples of meandering stream deposits from the Tertiary of the Southern Pyrenees show different types of sandbody. Individual active channel sequences in the three examples fit reasonably well the “classical” point-bar model. Lateral accretion bedding is clearly developed and indicates substantial discontinuity in point-bar growth. Accretion surfaces can be traced either throughout entire channel sequences or only through their upper portions. In two of the examples the point-bars are preserved as isolated bodies in a mudstone matrix. In the third example, stacked amalgamated point-bars form more extensive sandbodies which are interpreted as meanderbelts. These different modes of preservation of meandering stream deposits are thought to be dependent on: aggradation rate of the floodbasin, life-time of the channels, stability of position of meanderbelts in the floodbasin and presence of additional floodplain-mud suppliers other than the channels themselves.