Geochemistry of sediments from the Tyrrhenian Sea

Except in the two samples from Hole 651 A, it seems that zeolite crystallization does not play a role in the induration phenomenon. This latter appears to result from in situ clay authigenesis.

Secondary K-Fe beidellite or Fe-Mg beidellite form diagenetic growths and bridges between sedimented particles. Turbidites are rich in volcaniclastics (glass, pumices and other volcanogenic elements) but the induration phenomenon appears to be associated essentially with the occurrence of basaltic detritus. It is proposed that clay authigenesis results from low temperature alteration of basaltic fragments issued from Vavilov and probably Marsili seamounts in sediments isolated from seawater by overlying deposits.