Drilling on Transect EG66 (Fig. F1) had three primary objectives. The first objective was to determine the age of igneous crust at latitude 66°N northeast of Ocean Drilling Program (ODP) Site 988 (Duncan, Larsen, Allan, et al., 1996). Curiously, 40Ar-39Ar dating of one of the two Site 988 igneous units yielded anomalously young ages of 49.6 ± 0.2 Ma (Tegner and Duncan, 1999). This young age was unexpected because Site 988, from seismic and magnetic information, was interpreted to be located within 56- to 53-Ma Chron C24r basal lavas of the landward featheredge of the seaward-dipping reflector sequence. Site 988 results offered two equally plausible interpretations: (1) lava or sill from young, off-axis magmatism had been drilled, despite the lack of indications in the seismic data; and (2) the upper crust is indeed ~50 Ma in the latter region. Given the rather poorly developed seafloor magnetic zones in this area (see Fig. F6 in the "Introduction" chapter), this is a permissible hypothesis. Resolving these questions is most important for understanding the plate kinematic and accretionary processes of this part of the margin.
Subsequent to ODP Leg 163, high-resolution seismic data were collected by the H/V Dana cruise in the vicinity of Site 988 (Hopper et al., 1997). This work showed that the smooth morphology of the inner shelf landward of Site 988, originally interpreted as continental basement, was actually underlain by strong seaward-dipping reflectors. This landward continuation of oceanic crust was more consistent with the young age of basalt from Site 988, although the seafloor magnetic anomalies remained problematic. Thus, the second objective of Transect EG66 drilling was to sample crust from the inner shelf in the hope of closing the gap in our knowledge of the composition and age of the oldest volcanic crust in the region. The third objective was to recover the youngest crust possible for comparison with basalts from the Paleogene of Iceland and those recovered from Deep Sea Drilling Project Sites 407, 408, and 409 in Miocene crust of the Irminger Basin (Luyendyk, Cann, et al., 1979). This latter objective was also a priority for Leg 163 but was unrealized because of equipment problems.
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