Figure 2. ODP Leg 171B Blake Nose transect drill sites and the multichannel seismic Line TD 5. The MCS line with the drill site locations is shown in Figure 3.
Figure 3. Seismic interpretation of MCS Line TD-5 across Blake Nose showing the major reflectors, their ages, and location of drill sites. The location of the seismic line is shown in Figure 2.
Figure 4. Stratigraphic summary of Sites 1049-1053 on the drilling transect.
Figure 5. Susceptibility (bold line) and color (lighter line) in a series of 25-m panels that cover part of the mid-late Eocene section recovered at Site 1052. Both measurements show variability with a wavelength of ~1 m, which probably reflects variations in the Earth-Sun orbital geometry (Milankovitch cycles) that will be investigated post-cruise for use in cyclostratigraphy and orbital timing. Note that the color code is (L*a*b) times -1 to facilitate comparison to magnetic susceptibility data.
Figure 6. Middle and late Eocene magnetostratigraphy at Site 1052. This site has a very well defined magnetostratigraphy that we will attempt to calibrate in terms of the absolute duration of the various chrons using the cyclostratigraphy (Fig. 5) clearly documented at this site.
Figure 7. Susceptibility and color across the Paleocene/Eocene interval at Site 1049 displays what may be a precessional orbital cycle. The wavelength of the cycles in the Eocene (average sedimentation rate 25 m/m.y.) is consistent with an obliquity signal, whereas those in the Paleocene (average sedimentation rate 18 m/m.y.) are consistent with a precession signal. The change in the wavelength of the cyclicity across the Paleocene/Eocene boundary suggests that both a change in the response of the climate system from precession to obliquity control and an increase in long-term sedimentation rates occurred close to the Paleocene/Eocene boundary. Mcd = meters composite depth.
Figure 8. Summary of highly condensed interval in Core 1050C-20R that ranges in age from the late Turonian to late Campanian.
Figure 9. Lithium concentrations within pore waters at all Leg 171B sites.
Figure 10. The stratigraphic position of Cretaceous dark-gray laminated sediments recovered at Sites 1049, 1050, and 1052 in relation to the onlap curve of Haq et al. (1987).
Figure 11. Compilation of the three complete K/T boundary sections recovered at Site 1049 (Holes 1049A, 1049B, and 1049C).
Figure 12. Magnetostratigraphy of the lower portion of Hole 1052E. These high quality pmag data suggest Blake Nose was located at 23°N during late Albian and early Cenomanian, which is significantly different than the previously calculated paleolatitude of 30°N. Previous reconstructions have placed the middle Cretaceous North American pole 1000 km too far south.
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