Depositional Mechanisms from the Size Analysis of Clastic Sediments

ABSTRACT The problem of discrimination between the different mechanisms or processes and the different environments of deposition from the size distribution of coarse clastic sediments (gravels, sands, silts, and their lithified equivalents) has been investigated by satistical methods. Several discriminant functions with their levels of significance are established by multivariate discriminatory analysis in order to distinguish between adjacent mechanisms and environments having closely similar energy conditions. The variations in the sample statistics through space and/or time are concordant within the different mechanisms and environments. An empirical graph of 12 versus {[SKg]/[SMz] · S(12)} on a log-log paper is useful only when two or more number of samples are available for discrimination, but the discriminant functions can be used even for single samples. Presently, it is possible to distinguish between aeolian, marine, fluvial, and turbidity current mechanisms; and between littoral (beach) and shallow agitated water (down to 300 feet) environments within the spectrum of marine depositional processes.