Feldspar concentrations in lower Cambrian limestones of the Moroccan Atlas: Pyroclastic vs authigenic processes

The mineral and chemical composition of the host-rock and diagenetic fluids was the determining factor for the kind of feldspar preservation. Although the primary type of K-feldspar replacement is albitization, secondary albite subsequently suffered from illitization, chloritization, and/or replacement by calcite. A direct implication of this work is the possible geochronological dating of both volcanic eruptions and archaeocyath- and trilobite-bearing host-rocks based on radiometric analyses within unaltered K-feldspar pyroclasts extracted after etching.