STATISTISCHE METHODEN IN DER MIKRO‐BIOFAZIES

SUMMARY Statistical methods in micro‐biofacies This paper deals with statistical methods as applied to micro‐biofacies problems. The samples for the tests were taken from four quarries in Jurassic and Cretaceous limestones in northwestern Germany. The calculations are based on acetate‐peels. Two millions of figures were considered. The percentages of nine organic and nine inorganic components were calculated, hierarchically. In the beginning, the results were plotted as segments of circles. This way of representing the percentages of components just shows the general distribution of the main components. A more detailed picture can be given by plotting the distribution expressed in percentage, in reference to the distance of sampling points. The figures show the importance, not of the individual amplitudes, but of the average values of all amplitudes measured in one layer. Therefore, the change of the average amplitude represents a micro‐biofacies change of the layer under consideration. The measurements have shown that the differences in the distribution of the organic and inorganic components within the individual layers are not greater than those between the single layers. Correlation‐analyses had no positive results. Also tests of inhomogeneity did not give satisfying results. By decision‐analyses (discriminance‐analyses), however, it was possible to show small differences in the distribution of the components within the individual layers. Differentiations of the homogeneity and of the micro‐biofacies setting can be demonstrated by the intersections of the curves of the decision factors (=discriminance factors) and of the values of the arithmetic mean and sliding mean. By applying the X 2 ‐test and/or variance‐analyses, the boarder lines between fields of homogeneity can be shown accurately. Information about the homogeneity of the tested samples and the number of samples necessary for getting representative data, can be calculated from sequence tests.