A New Long Coring System for R/V Knorr



A new 46-meter-long coring system was tested successfully during cruise 191 of research vessel (R/V) Knorr in September 2007. During sea trials in water depths of 4.6 kilometers on the Bermuda Rise, coring operations from the vessel—operated by the Woods Hole Oceanographic Institution (WHOI)—successively recovered piston cores increasing in length from 26 to 38 meters, with sediment recovery at 85–89% of the core barrel length. An additional 25-meter core was recovered in 670 meters of water on the upper continental slope off New Jersey.

The Bermuda Rise location, which is a well-sedimented drift deposit at the northeastern margin of the rise, has been cored many times previously, including by R/V Knorr's giant piston corer in 1973, by R/V Marion Dufresne's Calypso corer in 1995, and by the Ocean Drilling Program's advanced piston corer (ODP/APC) in 1997. In comparing the sediment recovery of the systems, we determined that the WHOI long core recovered the stratigraphic section without any indication of stretching, effectively duplicating the results of the ODP/APC but without the unavoidable breaks between APC cores every 9.5 meters. In three deployments of the new corer, vertical compression occurred in the lower fourth of the core, while in two other deployments sediment recovery was undeformed for the full 38 meters of recovered sediment.