Physical deformation of Rochester shale and Opalinus clay; Impacts on isotopic signatures of clay minerals

Zwingmann, H.*; Berger, A.*; Todd, A.*; Niwa, Masakazu   ; Rahn, M.*

The present study investigates the influence of physical deformation via mechanical comminution and its influence on the isotope signatures of clay minerals, in a set of well-defined laboratory experiments using Rochester shale and Opalinus clay. Deformation experiments were carried out using different milling equipment, grinding force, time and temperature conditions. The integrated data obtained decipher physical deformation and temperature effects on Argon retention in clay minerals. We interpret the different radiogenic Ar loss ranges between the Rochester shale and Opalinus clay caused by different amounts of quartz and feldspar and different clay mineralogy of the starting materials. The shape and the hardness of the quartz/feldspar will influence the deformation of the clay particles inside the mill.