Condensation processes in shallow platforms

Abstract

Sequence stratigraphy allows elucidation of the time-space relationships of deposits in sedimentary basins.
However, the relative distribution of unconformities and condensed sections can neither be used as diagnostic
criteria for particular palaeogeographic settings, nor as indicators of maximum regional transgressions. Condensation
processes also occur in the shallowest portions of platforms and during maximum regression episodes. Three
separate processes of condensation are here distinguished: stratigraphic, sedimentary and taphonomic. These three
categories of condensation can be used to analyze patterns of sediment distribution, and also to estimate lateral and
vertical variations in sedimentation rates. Contrary to the usual interpretation, the maximum values of rate of
sedimentation and degree of accommodation of sediments, as well as the highest relative sea level, occur in the
lowest levels of the shallowing-upward sequences. The distinction between these condensation processes allows one
to predict that the degree of sedimentary and stratigraphic condensation will be higher towards the distal portions of
the platforms, whereas the stratigraphic condensation processes without sedimentary condensation will show the
maximum intensity and frequency in the shallowest portions of the platforms.