The recovery of continuous sedimentary sequences has been and is a high-priority goal of the Ocean Drilling Program, yet its success has not been determined. We test the stratigraphic continuity of continuously cored sequences from ODP Leg 111 Holes 677A and 677B and DSDP Leg 69 Hole 504. The two holes at Site 677 and Hole 504 are correlated using high-resolution biostratigraphy, tephra stratigraphy, and time series of opaline silica and calcium carbonate. The correlation coefficient between the time series is maximized through an inverse correlation procedure. Changes in slope of the mapping function that relates the two sections indicate gaps or changes in the accumulation rate between sections. We assume as a first approximation that the sedimentary sequences are identical in each hole, given their close proximity. 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.
Supplement to: Alexandrovich, Joanne M; Hays, James D (1989): High-resolution stratigraphic correlation of ODP Leg 111 Holes 677A and 677B and DSDP Leg 69 Hole 504. In: Becker, K; Sakai, H; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 111, 263-276
