Dating sediments by a K-Ar method

It is stated that attempts to date sedimentary rocks by isotopic methods have produced controversial results. That sedimentary rocks of known stratigraphic age have not been dated with any great success is considered to be one of the major disadvantages of the K-Ar method. Previous attempts have been unsuccessful because sediments contain argon which had been inherited from previous orogenic K-Ar events before weathering, transportation and deposition. This means that the time of sedimentation cannot usually be obtained by the standard calculation. A new method of dating sediments proposed here attempts to overcome this problem by using data from size-fractionated argillaceous sediments, treated by a graphical method of age calculation. (author)