The Newfoundland–Iberia rift (Fig. F1) is a non-volcanic rift that is an ideal location to examine overarching questions about the structure and evolution of non-volcanic rifted margins. Proposed Site NNB-01A in the central Newfoundland Basin, the prime site planned for drilling, is on "transitional" crust of uncertain composition between continental crust to the west and ocean crust exhibiting M-series (M0 and ?M3) magnetic anomalies to the east. Alternate sites in positions farther east along the transect (Fig. F2) are designed to obtain information about basement composition and structure at the seaward edge of the transition zone and onto probable ocean crust.

The primary objectives of Leg 210 drilling are

1. To determine whether the perceived asymmetry in deep and basement structure between the Newfoundland and Iberia margins is real, and if so, what mechanisms account for the deformation (e.g., simple shear?);
2. To understand the mechanical process responsible for pervasive unroofing of upper mantle off Iberia by constraining basement structure and evolution on the Newfoundland conjugate;
3. To investigate whether lithospheric thinning and removal of the continental crust occur with or without decompression melting of the asthenospheric mantle (e.g., was the entire rift amagmatic?);
4. To determine the nature and timing of rift events (e.g., end of rifting, subsidence, and initial seafloor spreading) in the Newfoundland Basin and to test correlations with events on the Iberia margin;
5. To relate spatial and temporal strain partitioning predicted from these events to features including symmetric or asymmetric extension, distribution of melt products in the rift, development of stratigraphic sequences, and well-documented synrift and "break-up" unconformities on the shallow margins;
6. To examine whether strain rates were sufficiently slow that conductive cooling suppressed melting of the rising asthenospheric mantle; and
7. To document the post-rift paleoceanographic history in this "gateway" between the North Atlantic and the sub-Arctic and Arctic Oceans.