Location of Repository

Site 1218

By J. Backman, W.H. Busch, H.K. Coxall, K. Faul, P.A. Gaillot, S.A. Hovan, T.R. Janecek, P. Knoop, S. Kruse, L. Lanci, C.H. Lear, M. Lyle, T.C. Moore, C.A. Nigrini, H. Nishi, R. Nomura, R.D. Norris, H. Pälike, J.M. Parés, L. Quintin, I. Raffi, B.R. Rea, D.K. Rea, T.H. Steiger, A.K. Tripati, M.D. Vanden Berg, B.S. Wade and P.A. Wilson

Abstract

Site 1218 (8°53.378´N, 135°22.00´W; 4828 meters below sea level [mbsl]; Fig. F1) is the sole site to be drilled on the 40-Ma transect during Leg 199 and will be used to investigate paleoceanographic processes in the equatorial Paleogene Pacific Ocean during the inferred transition of Earth's climate from the early Paleogene "greenhouse" into the late Paleogene "icehouse." Site 1218 is situated on a basement swell ~3° north of the Clipperton Fracture Zone in the central tropical Pacific Ocean. The age of basement at Site 1218 was poorly constrained prior to Leg 199 because the crust formed near the Eocene magnetic equator so that little magnetic anomaly data are available between the Clipperton and Clarion Fracture Zones (Cande et al., 1989). Thus, prior to Leg 199, our estimate for basement age at Site 1218 (~40 Ma) was based on previous drilling and assumed spreading rates. Nevertheless, at the outset of Leg 199 drilling, the availability of sediment descriptions from Deep Sea Drilling Project (DSDP) Sites 161, 574, and 575 meant that the Cenozoic history of sedimentation in the region of Site 1218 was better constrained than in the regions of Sites 1215, 1216, and 1217. Based on data from these rotary-cored holes, shallow-penetration piston cores taken near Site 1218 (taken on the site survey EW9709-7PC), and seismic profiling (Fig. F2), we expected the sedimentary sequence at Site 1218 to comprise a relatively thick (25 to 35 m thick) section of clays overlying radiolarian and nannofossil oozes to chalks of early Miocene-late Eocene age with little to no chert (estimated total depth ~250-280 meters below seafloor [mbsf]). <br/><br/> Site 1218 was chosen because it is anticipated to have been located on the equator at 40 Ma (at ~0°N, 107°W) based upon a fixed hotspot model (Gripp and Gordon, 1990, for 0- to 5-Ma Pacific hotspot rotation pole; Engebretson et al., 1985, for older poles) and because our interpretation of seismic data suggested that this site afforded the best possibility of penetrating Eocene/Oligocene (E/O) boundary sediments within the depth range of the Ocean Drilling Program's (ODP's) advanced piston corer (APC) system (~180 mbsf in these sediments). <br/><br/> The paleoceanographic and paleoclimatic objectives of drilling the sedimentary sequence anticipated at Site 1218 are as follows: (1) to help define the shift in the Intertropical Convergence Zone through the Paleogene by following the change in eolian dust composition and flux (red clays) through time; (2) to help constrain changes in the calcite compensation depth (CCD) from the late Eocene to the early Oligocene; (3) to obtain a complete Oligocene section of tropical-assemblage carbonate and siliceous microfossils with good magnetostratigraphic control; and (4) to sample the E/O boundary, late Oligocene, and Oligocene/Miocene (O/M) boundary, three of the most climatologically interesting intervals of Cenozoic time. Recovery of deep-sea sediments from above the CCD across the E/O boundary time interval during Leg 199 is a particularly high priority because complete E/O boundary sections for this time interval are not available from the Pacific Ocean

Topics: QE
Publisher: Texas A & M University Ocean Drilling Program (CDROM)
Year: 2002
OAI identifier: oai:eprints.soton.ac.uk:41908
Provided by: e-Prints Soton

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  1. (mg/cm 2/k.y.) Lithologic Unit I Lithologic Unit II Lithologic Unit III Lithologic Unit IVSHIPBOARD SCIENTIFIC PARTY CHAPTER 11, SITE 1218 64 Figure F21. Interstitial water data from Site 1218. Solid circles
  2. 97 Table T6. Planktonic foraminifer datum levels,
  3. (1998). A practical guide to wavelet analysis.
  4. (1995). A revised Cenozoic geochronology and chronostratigraphy. In
  5. (2000). accumulation rates (MARs) of sediments at
  6. (1999). Astronomical calibration of Oligocene-Miocene time.
  7. (1988). Biostratigraphy of the Eocene-Oligocene boundary at Massignano
  8. (1989). Cenozoic bathyal and abyssal calcareous benthic foraminiferal zonations.
  9. (1986). Cenozoic cosmopolitan deep-water benthic foraminifera.
  10. (1975). Cenozoic history and paleoceanography of the central equatorial Pacific Ocean: a regional synthesis of Deep Sea Drilling Project data.
  11. (1990). Current plate velocities relative to the hotspots incorporating the NUVEL-1 global plate motion model.
  12. Early Oligocene–early Miocene section.
  13. (1993). Heat flow from the earth’s interior: analysis of the global data set.
  14. (1973). Low-latitude coccolith biostratigraphic zonation. In
  15. (1989). Magnetic lineations of the world’s ocean basins.
  16. (1983). Neogene Planktonic Foraminifera: A Phylogenetic Atlas:
  17. p t h ( m b s f ) R e c o v e r y C o r e R e c o v e r y C o r e R e c o v e r y Hole 1218A Hole 1218B Hole
  18. (1985). Paleocene and Eocene planktonic foraminifera. In
  19. (1995). Paleogene to Neogene deep-sea paleoceanography in the eastern Indian Ocean: benthic foraminifera from ODP Sites 747, 757, and 758.
  20. (1973). Printing Office).
  21. (1996). Radiolarian stratigraphy across the Oligocene/ Miocene transition.
  22. (1995). Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous
  23. (1985). Seismic modeling and paleoceanography at Deep Sea Drilling Project Site 574. In
  24. SITE 1218 51 Figure F10. Archive-half magnetization intensities after AF demagnetization at a peak field of 20 mT at Hole 1218A. Lithologic units are shown on the right. Intensity (A/m) D e p t h ( m c d ) L i t h . u n i t
  25. SITE 1218 56 Figure F13. Gamma ray attenuation (GRA) bulk density data for Holes 1218A (left curve in each panel), 1218B (middle curve in each panel), and 1218C (right curve in each panel) plotted vs. composite depth.
  26. (1971). Standard Tertiary and Quaternary calcareous nannoplankton zonation. In Farinacci,
  27. (2001). Table T1. Coring summary, Site 1218. (See table note. Continued on next two pages.) Hole 1218A Latitude: 8°53.3667′N Longitude: 135°22.0002′E Time on site (hr): 179.75 (0115 hr,
  28. (2002). the CD-ROM version of this volume was published, errors were noted in the ASCII versions of Tables T3, T8, T10, T11, T14, T17, T18, T19, and T20. This version contains the corrected ASCII files.
  29. The data from Holes 1218B and 1218C are offset by constants for illustration purposes. All data sets are smoothed with a nine-point Gaussian filter. Intervals with obvious flow-in or drilling disturbance were removed from the data sets (see Table T10,
  30. (1962). The mid-Tertiary (upper Eocene to Aquitanian) Globigerinacea. In
  31. (2000). Thermal data collection and heat flow recalculations for ODP Legs 101–180. Institute for Joint Geoscientific Research,
  32. Thermal resistance based on a linear increase in thermal conductivity in lithologic Unit II between 55.11 and 173.46
  33. This table is also available
  34. This table is also available in ASCII. [N1] 26X-1,
  35. (1989). This table is also available in ASCII. [N1] Marker species/ Zonal boundaries Age (Ma) Depth (mcd) ± (m) Nannofossil events: B Catinaster coalitus 10.80
  36. This table is also available in ASCII. Core, section, interval (cm) Depth (mbsf) pH Alkalinity (mM) Salinity Cl (mM) Na (mM) K (mM) Ca (mM) Mg (mM) SO4 (mM) NH4 (µM) H4SiO4 (µM) Sr (µM) Li (µM) Mn (µM) Ba (µM) B (µM) 199-1218A1H-4,
  37. (1218). This table is also available in ASCII. Core, section, interval (cm) Depth (mbsf) Thermal conductivity (W/[m·K
  38. (1995). top or highest occurrence, B = bottom or first occurrence. Ages are those of

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