Fossilization of radiolarian skeletons

Questions of radiolarian skeleton fossilization are analyzed. Complete disruption of the primary organic matrix of the skeleton and different lithogenetic conditions, on the one hand, cause disintegration of skeletons into fragments and, on the other hand, facilitate the fusion of adjacent mineral units and realization of the trend of silica towards structural improvement in the successive series of globular opal A → opal CT → low-temperature tridymite → low-temperature quartz. Transformation of opal A into opal CT and quartz is under control of temperature and time. Thus, modifications of SiO 2 in radiolarian skeletons possibly show a response to respective stages of lithogenesis: sedimentogenesis → diagenesis → early catagenesis → late catagenesis. Great attention is paid to pyritization of skeletons under conditions of hydrosulphuric contamination. It is shown that, in the radiolarian skeleton, silica was secondarily replaced by other minerals.