The history of drilling on the Antarctic continental shelf since 1973 is summarized in Fig. 3.9. Both ship-based and floating ice-based operations typically take 5-15 years from conception to execution and require the involvement of a committed group of scientists to execute successfully. The excellent core quality and recovery (95-98%) has come about because of the use of minerals industry technology, which is designed for optimal core recovery, and a sea riser that allows the circulation of a fluid of the right density and viscosity to remove cuttings and protect hole and core. This technique has now been used to drill over 1,200 m beneath the sea floor and in water almost 1,000 m deep. The ability to re-enter a pre-existing hole, which would be potentially useful for drilling beneath rapidly moving ice shelves, has yet to be developed, but considered feasible (A. Pyne, personal communication, 2008). This may well be useful for ANDRILL's proposed site on the ice shelf east of Ross Island to sample through early Cenozoic strata and capture the transition from the ''greenhouse'' world on the Antarctic margin (Decesari et al., 2004).
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