CONCLUSIONS

We have linked core data at Leg 210 Site 1276 with coincident seismic reflection data from the SCREECH experiment by creating synthetic seismograms from shipboard laboratory measurements of velocity and density. Because laboratory measurements were made on discrete, hand-selected samples, in contrast to the regularly spaced measurements included within a logging data set, some additional processing was required. The resulting synthetic seismograms demonstrate the following ties:

  1. The lithologic Unit 1/2 boundary corresponds to a bright reflection observed at ~7.02 s in seismic reflection data (Figs. F2, F10A; Reflection AU1). Seismic stratigraphic character and biostratigraphy (Tucholke and Sibuet, this volume; Wood et al., submitted [N1]) indicate that the AU1 reflection does not correlate with the regional Horizon AU reflection observed in the main North Atlantic basin to the south. Instead, a shallower reflection at 6.96 s (AU2) most likely corresponds to Horizon AU (Tucholke and Sibuet, this volume). This reflection lies at the top of the cored section at Site 1276 (~800 mbsf) and dates approximately to the Eocene/Oligocene boundary.
  2. The bright reflections found between 7.02 and 7.19 s in seismic reflection data result from interlayering of carbonate-cemented sandstone and claystone with mudrock in Units 2–4.
  3. The base of Unit 4 correlates with an apparent seismic unconformity at ~7.19 s in seismic reflection profiles across Site 1276. Shipboard biostratigraphy suggests either a hiatus or low sedimentation rates in this interval.
  4. Finally, our synthetic seismograms demonstrate that the prominent U reflection at Site 1276 is caused by the shallower of two postrift igneous sills. An underlying strong reflection is caused by a second, deeper postrift sill. Further work will be required to understand potential relationships between igneous sills and the U reflection across the Newfoundland Basin away from Site 1276.

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