Small-diameter vibrocorer for sediment coring beneath Antarctic ice shelves: General concept and testing

摘要

Samples from beneath Antarctic ice shelves, ice streams, and subglacial lakes contain important paleoclimatic and paleoenvironmental records, and these environments also provide a unique habitat for life. This paper describes a small-diameter SUBglacial SEdiment Vibrocorer (SUBSEV) designed especially for coring sediments from beneath Antarctic ice shelves through an access hole formed with a hot-water drill. The maximum diameter of the SUBSEV corer is 270 mm, the total length of the corer is 4.1 m, it weighs 214 kg, it is designed to sample at least 3 m of sediment without disturbance, and it can work at water depths down to 3000 m. A cylindrical, self-synchronous, dual-motor vibrator was designed to deal with the size restrictions of the hole. Actuating motors rotating in opposite directions can generate vertical, horizontal, or alternative vibrations. In the course of laboratory testing, the SUBSEV corer easily penetrated to a depth of 3.4 m in a sediment composed of fine-screened sand, loess, and soil with a coring speed of 70-100 mm/s. The maximum penetration speed was reached in the alternate vibration mode. Field testing of the SUBSEV corer is planned within a hot-water ice-drilling project on Amery Ice Shelf, East Antarctica in the 2017-2018 season.