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Questions? Discussion?

Age Model Exercise I. Questions? Discussion?. Note: FA = FO and LA = LO throughout investigation!. Leg 208 - Oceanographic Setting. Walvis Ridge South Atlantic. Questions? Discussion?. NW Perspective View.

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Questions? Discussion?

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  1. Age Model Exercise I Questions? Discussion? Note: FA = FO and LA = LO throughout investigation!

  2. Leg 208 - Oceanographic Setting Walvis Ridge South Atlantic Questions? Discussion? NW Perspective View

  3. “Age-Depth_Cenozoic” Worksheet Original Questions? Discussion?

  4. Part I. Determine absolute ages for planktonic foraminifera FAs and LAs Example: Row 36 of “Site_1262” Worksheet: LA M. aragonensis

  5. Part I. Determine Absolute Ages for FAs and LAs of Planktonic Foraminifera Example: Row 36 of “Site_1262” Worksheet: LA M. aragonensis Table 9 of Berggren et al. (1995): Datum 28 . . . 52.3 Ma

  6. “Age-Depth_Cenozoic” Worksheet with PF Datums Questions? Discussion?

  7. Part II. Uniquely Identify Magnetochron Reversals and Their Absolute Ages Example: Row 41 of “Site_1262” Worksheet: PM-NormOnset

  8. Part II. Uniquely Identify Magnetochron Reversals and Their Absolute Ages Example: Row 41 of “Site_1262” Worksheet: PM-NormOnset Table 2 of Berggren et al. (1995): Onset of C24n.3n aka C24n 53.347 Ma Note that Table 2 lists only the terminations and onsets of normal magnetochrons!

  9. “Age-Depth_Cenozoic” Worksheet with PF and PM Datums Questions? Discussion?

  10. Leg 208 - Oceanographic Setting Walvis Ridge South Atlantic Questions? Discussion? NW Perspective View

  11. Carbonate Sedimentation Patterns (from Trujillo & Truman, 2005)

  12. Carbonate Sedimentation Processes • CaCO3 solubility increases with: • Decreasing Temperature • Increasing Pressure • Increasing CO2 • Calculated calcite saturation curve • Typical carbonate ion concentration • Carbonate Compensation Depth (CCD) • <20 wt% CaCO3 • Modern depth: 3.5-4.5 km (from The Open University)

  13. Estimating PaleoCCD from CoresSimplified shelf:basin compensation model Sea Level Continental Shelf CCD Ridge Abyssal Plain Abyssal Plain Site receives less than 20 wt% CaCO3

  14. Estimating PaleoCCD from CoresSimplified shelf:basin compensation model Sea Level Continental Shelf CCD Ridge Abyssal Plain Abyssal Plain Site receives greater than 20 wt% CaCO3

  15. Paleodepth Reconstruction Sea Level and CCD display a positive correlation Other related controls include: CO2, Ca, and CO32- ion supply from weathering (from Van Andel, 1979)

  16. Age Model Exercise I Site 1263 (Shallow) Site 1262 (Deep) Questions? Discussion? (from Leg 208 Initial Reports)

  17. Spatiotemporal Variations in Wt% Carbonate in Leg 208 Sites Questions? Discussion? (from Leg 208 Initial Reports)

  18. Part III. Biomagnetostratigraphic Constraints on the . . .

  19. Eocene Layer of Mysterious Origin Paleocene-Eocene Thermal Maximum Recovery 139.22 mcd Questions? Discussion? ~118 kyr Onset 140.12 mcd Onset 117.62 mcd (from Lourens et al., 2005) (from Zachos et al., 2005)

  20. “Age-Depth_ELMO_PETM” Worksheet Questions? Discussion?

  21. Eocene Layer of Mysterious Origin Paleocene-Eocene Thermal Maximum Recovery 139.22 mcd Questions? Discussion? ~118 kyr Onset 140.12 mcd Onset 117.62 mcd (from Lourens et al., 2005) (from Zachos et al., 2005)

  22. Elmo age = 0.0828*mcd+43.389 = 53.128 Ma If one uses the CN linear regression model . . . Questions? Discussion?

  23. Eocene Layer of Mysterious Origin Paleocene-Eocene Thermal Maximum Recovery 139.22 mcd Questions? Discussion? ~118 kyr Onset 140.12 mcd Onset 117.62 mcd (from Lourens et al., 2005) (from Zachos et al., 2005)

  24. Elmo age = 0.0828*mcd+43.389 = 53.128 Ma PETM age = 0.0828*mcd+43.389 = 54.916 Ma If one uses the CN linear regression model . . . Questions? Discussion?

  25. Eocene Layer of Mysterious Origin Paleocene-Eocene Thermal Maximum Recovery 139.22 mcd Questions? Discussion? ~118 kyr Onset 140.12 mcd Onset 117.62 mcd (from Lourens et al., 2005) (from Zachos et al., 2005)

  26. Elmo age = 0.0828*mcd+43.389 = 53.128 Ma PETM age = 0.0828*mcd+43.389 = 54.916 Ma If one uses the CN linear regression model . . . Questions? Discussion? Elmo–PETM onset interval = 54.916-53.128+0.118 = 1.906 = 1.91 Myr

  27. Elmo PETM Chron C24n C24r Epoch Early Eocene Age Ypresian PFZ P6b P5 CNZ NP11 NP9

  28. Mass Accumation Rates (MARs) • Linear sedimentation rate (LSR) vs. mass accumulation rate (MAR) • MAR calculation: Y something (moles, counts, etc.) * dry bulk density (g/cm3) * LSR (cm/kyr) • Resulting MAR units: Y something cm-2 kyr-1 (e.g., 127 g CaCO3 cm-2 kyr-1; 127 benthic foraminifera cm-2 kyr-1)

  29. Age Model Exercise I Site 1263 (Shallow) Site 1262 (Deep) Questions? Discussion? (from Leg 208 Initial Reports)

  30. Site 1263 (Shallow) Site 1262 (Deep) (from Leg 208 Initial Reports)

  31. “Age-Depth_ELMO_PETM” Worksheet Questions? Discussion?

  32. Age Model Round-Up • • • • • • •

  33. Age Models – Gots, Needs, etc. • Getting/giving data: IODP Janus, NGDB, journal archiving/appendices • Depths/heights are static, age models evolve • Primacy of age models: Interpretations built on rock or sand? • Effects of changing sedimentation rates on age models • Cyclostratigraphy: Going from space- to time-domain • Garbage in, garbage out: Analyzing 18O for periodicity

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