Kalium-Argon-Daten zum Alter des Laacher Vulkanismus, der Rheinterrassen und der Eiszeiten

Abstract. The volcanic rocks of the Laacher-See-area in the Eifel can be correlated chronologically with the formation of terraces by the River Rhine. Thus the sequence of these rocks becomes stratigrafically determinable. This offers a possibility for testing the K-Ar-dating-method with samples of Pleistocene age and for checking the correspondance of the physically determined sequence and the geological sequence. Specimens of 13 sanidines, 7 biotites, 2 augites, 14 rocks of the Eifel, and — in addition — 6 rocks of the environment of Agde, Dept. Hérault, in southern France were dated with geological likely ages resulting in most cases. In the Eifel they reach from 570.10³a to 100.10³a, at Agde from 1400.10³a to 640.10³a. Experiments of diffusion with sanidines and biotites demonstrated, that atmospheric Argon cannot be sufficiently removed by heating without loss of radiogenic Argon. A control-sample of the heated radiogene gas with radioactive Ar(39) was tested and proved to be a usful correction-factor.