Calcium carbonat content and stratigraphic correlation of ODP Leg 111 sites and DSDP Leg 69-504

Slope changes of the mapping functions therefore result from errors introduced by coring. This assumption is justified by the fact that most mapping function slope changes occur at core breaks. Having identified missing sections in one site, it is possible to fill these gaps with the appropriate section from the adjacent site, thereby improving continuity.

This is possible only where the sediment gaps identified at core breaks in one hole do not correspond to core break levels in the other hole. Results show that in the upper 100 m of the stratigraphic column, 3.1% and 4.6% were unsampled in Holes 677A and 677B, respectively, and 15% of the Pliocene portion of Hole 504 was not sampled by the hydraulic piston corer. This indicates that even in relatively calm seas, double or triple coring is required in order to ensure that gaps and doubly sampled intervals of the stratigraphic column which occur at core breaks are recognized and sampled at least once.