Integrated stratigraphic correlation and improved composite depth scale for ODP Sites 1218 and 1219

During Ocean Drilling Program Leg 199 a high-resolution (~1–2 cm/ k.y.) biogenic sediment record from the late Paleocene to the early Mio- cene was recovered, containing an uninterrupted set of geomagnetic chrons as well as a detailed record of calcareous and siliceous biostrati- graphic datum events. Shipboard lithologic proxy measurements and shore-based determinations of CaCO3 revealed regular cycles that can be attributed to climatic forcing. Discovering drill sites with well de- fined magneto- and biostratigraphic records that also show clear litho- logic cycles is rare and valuable and creates the opportunity to develop a detailed stratigraphic intersite correlation, providing the basis to study paleoceanographic processes and mass accumulation rates at high resolution. Here we present extensive postcruise work that extends the ship- board composite depth stratigraphy by providing a high-resolution re- vised meters composite depth (rmcd) scale to compensate for depth dis- tortion within individual cores. The depth-aligned data were then used to generate stacked records of lithologic proxy measurements. Making use of the increased signal-to-noise ratio in the stacked records, we then proceeded to generate a detailed site-to-site correlation between Sites 1218 and 1219 in order to decrease the depth uncertainty for magneto- and biostratigraphic datums. Stacked lithologic proxy records in combi- nation with discrete measurements of CaCO3 were then exploited to calculate high-resolution carbonate concentration curves by regression of the multisensor track data with discrete measurements. By matching correlative features between the cores and wireline logging data, we also rescaled our core rmcd back to in situ depths. Our study identifies li- thology-dependent core expansion due to unloading as the mechanism of varying stratigraphic thicknesses between cores.