Studies on bedded cherts

Abstract

Radiolarian cherts from two localities in North-western Italy have been studied by optical and scanning electron microscopy, X-ray diffraction and X-ray fluorescence analysis. The quality of preservation of the radiolarians decreased from dark red to pale cherts. The effect of diagenetic processes (solution, reprecipitation and recrystallization) was least in red cherts where contained hematitic and clay material inhibited the movement of pore solutions, and greatest in the pale cherts resulting in the destruction of the original skeletal material. It is suggested that these radiolarian cherts were produced from an accumulation of siliceous radiolarian skeletons subsequently altered diagenetically with consequent loss of skeletal structure.