1 / 14

Oxygen and Hydrogen Combined

D/  18 O. Oxygen and Hydrogen Combined. hydrogen isotopes -. D =. D/ 18 O. meteoric H 2 O = connate H 2 O = magmatic H 2 O =. higher fractionation between liquid & water. lower T (or higher elevation). =.

thomas-williams
Download Presentation

Oxygen and Hydrogen Combined

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. D/ 18O Oxygen and Hydrogen Combined hydrogen isotopes - D = D/18O meteoric H2O = connate H2O = magmatic H2O =

  2. higher fractionationbetween liquid & water lower T(or higher elevation) = “The Application of Oxygen and Hydrogen isotope Studies to Problems of Hydrothermal Alteration and Ore Deposition”, Hugh P. Taylor, Economic Geology, Vol. 69, 1974, p. 843-883

  3. “Essentials of Geochemistry”, John V. Walther, 2005

  4. 18O/16O is used as a geothermometer. Samples taken from glacier ice cores and the calcareous shells of marine organisms with calcareous shells have been used to shed light on ice age climatic changes, the temperatures of ancient oceans, and global warming (Krauskopf & Bird p. 263-264). Oxygen CaCO3 (as calcite and aragonite) is secreted by marine organisms. An equilibrium is established with H2O in seawater – 1/3 CaC16O3 + H218O = 1/3 CaC18O3 + H216O K = • Measure 18O/16O in calcareous sediments and determine fluctuations in sea temperature (and therefore atmospheric T’s) 100,000 to 200,000 years ago. It’s assumed – • 18O/16O in seawater constant over geologic time (SMOW constant) • 18O/16O in shells constant from species to species • no changes since deposition

  5. 16O 18O http://en.wikipedia.org/wiki/Foraminifera Marine Organisms and Paleotemperatures The temperatures of ancient seas are measured using the 18O content of foraminifera shells (there are surface and bottom-dwelling species). An equation has been empirically derived - T(oC) = 16.9 – 4.2 (c - w) + 0.13 (c - w)2 where (c - w) = per mil (o/oo) difference between CO2 derived from shell by reaction with H3PO4 at 25 oC (c), and CO2 equilibrated with seawater at 25 oC (w).

  6. “Paleoclimatology: Reconstructing Climates of the Quaternary”, by Raymond S. Bradley, Academic Press, 1999

  7. Scientific American February 2007 http://commons.wikimedia.org/wiki/Maps_of_Greenland

  8. http://en.wikipedia.org/wiki/Antarctic_ice_sheet It’s happening in Antarctica, too. Ross Ice Shelf http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=6779

  9. Ice Core Drill

  10. Comparisons Greenland ice core North Atlantic Ocean sediments Revised Fig 6-12 (Bradley, 1999)

More Related