9-7. Piston Corer

T. Sugawara and M. Matsuhashi (Marine Works Japan Ltd.)

The piston corer system was used during this cruise was composed of a super-long aluminum alloy pipes system without a core liner. This piston corer can use a 20 m-long maximum core barrel. 5 m-long Aluminum alloy pipes, whose outer diameter is 92mm and inner one is 80 mm, were connected by sleeves to make 15 m-long and 10 m-long piston corers at each site. The pipes were attached to a 1.5 ton (in air) piston core head. We generally don't use a 1.5 ton head for a 10 m-long piston corer. However, we used one for the 10 m-long piston corer in this cruise because we expected sediments such as volcanic sand, which are very hard.

The piston corer was deployed and recovered by a 12,000-m wire winch and an "A-flame". The ship and winch control are coordinated by a watching the tension gage.

We collected six cores during this cruise. The pipes of the 5-6 m section were often bent. This indicated that there is a hard layer 5-6 m below sea floor. We recognized it was difficult to recover more than 10 m-long cores in this area
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The recovered cores are pushed out of the core barrel by using an oil pressure extruder. The cores are then cut into 1 m lengths for the convenience of analysis.

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