Age assignment of marine δ18O stratigraphies based on tuning
For this exercise you will use data sets obtained from DSDP Site 607 (41.002N, 32.957W, 3427 m water depth). The goal is to translate the depth-based δ18O and δ13C stratigraphies into an age model. This should be done by using the age tie-points provided by paleomagnetic events measured in sediments from the same site. Additional tie point can be obtained by comparing the age-depth curve to June insolation values.
Step 1
Copy and paste the data sets (Data set 1 below) from the text file into your excel spreadsheet. Create a plot showing δ18O and δ13C values against depth. Save this plot and describe and discuss the general features displayed by the two curves.
Step 2
Use the paleomagnetic events (Data set 2 below) as tie-points and, assuming constant sedimentation rates between tie-points, calculate an age for the sequence. Each δ18O and δ13C value should now have an age assigned. Make a plot for both data sets, describe and discuss the general features of the plot and compare this plot with your previous plot.
Step 3
You can now take your age-depth plots a step further and compare them with summer insolation values for the Northern Hemisphere. These data sets have been provided by A Berger and MF Loutre at: https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/orbital_variations/insolation/
Is there a possibility that you could use these insolation values as further tie-points to better constrain the age of your sequence?
Step 4
Submit your plots, a short description of the plots and a discussion of the climatic features seen in the two curves as a file attachment (.doc, .pdf)
Data set (DSDP Site 607) references
Cande SC, Kent DV (1992). A new geomagnetic polarity time scale for the late Cretaceous and Cenozoic. Journal of Geophysical Research 97:B10, 13917-13951.
Raymo ME (1992). Global climate change: a three million year perspective. In Kukla, G. and Went, E. (eds.), Start of a Glacial, Proceedings of the Mallorca NATO ARW, NATO ASI Series I, Vol. 3, Springer-Verlag, Heidelberg, p. 207-223.
Raymo ME, Nisancioglu KH (2003). The 41 Kyr world: Milankovitch’s other unsolved mystery. Paleoceanography 18:10.1029/2002PA000791.
Raymo ME, Ruddiman WF, Backman J, Clement BM, Martinson DG (1989). Late Pliocene variation in Northern Hemisphere ice sheets and North Atlantic deep circulation. Paleoceanography 4:413-446.
Ruddiman WF, Raymo ME, Martinson DG, Clement BM, Backman J (1989). Mid-Pleistocene evolution of Northern Hemisphere climate. Paleoceanography 4:353-412.
Shackleton NJ, Berger A, Peltier WR (1990). An alternative astronomical calibration of the lower Pleistocene timescale based on ODP Site 677. Transactions of the Royal Society of Edinburgh, Earth Science 81:251-261.
