(Table T1) Lithology, structure and significant components of sediments from ODP Holes 173-1068A and 173-1069A

Thin sections of samples were studied from (syn-?) postrift sediments of the Iberia Abyssal Plain (Ocean Drilling Program Leg 173, Sites 1068 and 1069). They show that, at these sites, Lower Cretaceous calcareous chalks and calcareous mass-flow deposits are overlain by sub-calcite compensation depth pelagic claystones of Late Cretaceous to early Tertiary age. At both sites, turbidites and current-controlled sequences are intercalated with pelagic claystones and show similar variations: (1) the proportion of turbidites to pelagic clay varies systematically and (2) turbidite composition changes from relatively coarse-grained and calcareous to predominantly fine-grained siliciclastic. This facies transition occurs around the Paleocene/Eocene boundary. In addition, turbidites at the Cretaceous/Tertiary and the Paleocene/Eocene boundaries contain resedimented glauconite, and, occasionally, some pyrite.