Biogenic and inorganic cherts

Results of the Deep Sea Drilling Project (DSDP) have led to an enormous increase in our knowledge of oceanic chert formation (1, 7, 8, 24, 26). Before the DSDP, cherts were almost exclusively studied on the terrestric parts of the continents, and many of the older papers on chert formation suggest inorganic genesis for quartzous cherts, while organic genesis was excluded in many theories. The results of the DSDP. that are mainly based on the study of biogenic cherts (porcelaniles) turned the scales the other way, and many authors now defend an exclusively organic genesis for most cherts. Some authors (43) even allow themselves fulminations against those investigators who still believe in the possibility of inorganic chert formation. The dinial of the possibility of inorganic chert formation is mainly due to the fact that till now no reasonable mechanism was proposed. The present paper intends to point out that, although cherts are indeed frequently of organic origin, inorganic formation should not be ruled out beforehand.