ODP Leg 163 was the second of two drilling legs to the Southeast Greenland margin to core an enormous pile of subaerially, erupted basalts associated with continental breakup that occured in the early Tertiary. Together with Leg 152 this program addressed the nature of rifting and breakup at this rifted continental margin and, in particular, assessed the impact of the Iceland mantle plume on breakup and early spreading. These investigations build on earlier DSDP and ODP drilling of seaward-dipping reflector sequences (SDRSs) on the Rockall and Vøring Plateaus (Legs 81 and 104), with the these SDRS occurrences and associated extensive subaerial exposures of Tertiary basalts on Greenland, the Faeroe Islands, and western British Isles collectively forming the North Atlantic Volcanic Province. Principle results are as follows:
1. completion of the record of volcanic evolution of the East Greenland margin at latitude 63°N, from continental breakup to oceanic crustal production;
2. fundamental constraints on the age of SDRS volcanism, from preliminary identification of the first two magnetic polarity reversals yet discovered in the East Greenland SDRS; and
3. the identification that the Iceland plume mantle component is more strongly expressed in the composition of the basalts at latitude 66°N compared with 63°N.
The third result, together with previous evidence from DSDP Leg 81 and ODP Leg 104, provides sufficient information to map the basic compositional structure of the mantle melting regime that existed during the initiation of the Iceland plume and breakup of the North Atlantic.
To 163 Introduction
163 Table of Contents