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

Questions? Discussion? Leg Oceanographic Setting NW Perspective View Walvis Ridge South Atlantic

Questions? Discussion? “Age-Depth_Cenozoic” Worksheet Original

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

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 Ma

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

Example: Row 41 of “Site_1262” Worksheet: PM-NormOnset 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 Ma Note that Table 2 lists only the terminations and onsets of normal magnetochrons!

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

Questions? Discussion? Leg Oceanographic Setting NW Perspective View Walvis Ridge South Atlantic

Carbonate Sedimentation Patterns (from Trujillo & Truman, 2005)

Carbonate Sedimentation Processes CaCO 3 solubility increases with: –Decreasing Temperature –Increasing Pressure –Increasing  CO 2 Calculated calcite saturation curve Typical carbonate ion concentration Carbonate Compensation Depth (CCD) – <20 wt% CaCO 3 –Modern depth: km (from The Open University)

Estimating PaleoCCD from Cores Simplified shelf:basin compensation model Sea Level CCD Site receives less than 20 wt% CaCO 3 Continental Shelf Abyssal Plain Ridge Abyssal Plain

Sea Level CCD Continental Shelf Abyssal Plain Ridge Abyssal Plain Site receives greater than 20 wt% CaCO 3 Estimating PaleoCCD from Cores Simplified shelf:basin compensation model

Paleodepth Reconstruction Sea Level and CCD display a positive correlation Other related controls include:  CO 2, Ca, and CO 3 2- ion supply from weathering (from Van Andel, 1979)

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

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

Part III. Biomagnetostratigraphic Constraints on the...

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

Questions? Discussion? “Age-Depth_ELMO_PETM” Worksheet

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

Questions? Discussion? If one uses the CN linear regression model... Elmo age = *mcd = Ma

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

Questions? Discussion? If one uses the CN linear regression model... Elmo age = *mcd = MaPETM age = *mcd = Ma

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

Questions? Discussion? If one uses the CN linear regression model... Elmo age = *mcd = MaPETM age = *mcd = Ma Elmo–PETM onset interval = = = 1.91 Myr

ElmoPETM ChronC24nC24r Epoch Early Eocene Age Ypresian PFZ P6b P5 CNZ NP11 NP9

Mass Accumation Rates (MARs) Linear sedimentation rate (LSR) vs. mass accumulation rate (MAR) MAR calculation: Y something (moles, counts, etc.) * dry bulk density (g/cm 3 ) * LSR (cm/kyr) Resulting MAR units: Y something cm -2 kyr -1 (e.g., 127 g CaCO 3 cm -2 kyr -1 ; 127 benthic foraminifera cm -2 kyr -1 )

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

Site 1262 (Deep) Site 1263 (Shallow)

Questions? Discussion? “Age-Depth_ELMO_PETM” Worksheet

Age Model Round-Up

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  18 O for periodicity