Sediment Sorting Related to Basin Mobility and Environment

Abstract

Environment analysis and paleogeographic reconstruction are used increasingly in petroleum exploration to evaluate distribution of source and reservoir rocks in a basin and to delimit areas that may include stratigraphic traps. This paper introduces an aid to environment and paleogeographic investigations which may bring significant progress to petroleum exploration. Sorting of clastic sediments is related to basin mobility and environment, but traditional sorting parameters are a function of so many independent variables that the relations are not clear. Two new sorting parameters are introduced. They define the sorting of a clastic deposit as a whole by the sorting of selected sediments deposited under known hydrodynamic conditions. These new parameters, clearly related to basin mobility and environment, show how sediments are distributed in a basin and indicate significant texture changes corresponding to changes in the environment. The proposed parameters also contribute to the analysis of transport and deposition of sediments. Particularly, these sorting parameters show and explain differences between fluviatile and shallow-marine sands, and between turbidites and the shallow sands that form the turbidity currents. Measurements of the sorting parameters require only a limited number of samples. Measurement techniques are simple and do not require complex calculations. Maps, easily constructed, show clearly the significant texture changes.