Green clay layers in sediments from the SCS may result from the diagenetic alteration of the original detritus brought in from the Asian continent. The geometric relation to the host sediments and the differences, though small, in mineralogy, grain size, and geochemistry between the GCLs and the background sediments seem to favor the hypothesis that these layers represent the outcome of initial steps of glauconitization. Relatively high organic carbon content possibly set up localized reducing microenvironments, which started the glauconitization process. No striking evidence exists that points to a volcanic origin of the initial material. The temporal distribution of GCLs, although probably biased during the recording process on board, shows interesting correspondence to sea level and neotectonism curves, pointing to a possible influence of eustatism on the formation of the layers. Changes in the depth of the active glauconitization process and frequent turbidites, which provided material to the sites, are, in fact, the two most likely responsible processes.
We are far from having deciphered the ultimate process responsible for the formation of GCLs, but considering their widespread distribution in the ocean sediments and the possible amount of information they may bear, related to factors such as eustatism, climate, and tectonism, the complete understanding of their nature and genesis may require further investigation.