1 / 18

In-situ SIMS U-Pb dating of Wyoming and Siberian dikes

In-situ SIMS U-Pb dating of Wyoming and Siberian dikes. Presentation for CAMIRO Project 08E03 ‘Reconstruction of supercontinents back to 2.7 Ga’ Project meeting March 3, 2012 Kevin Chamberlain, University of Wyoming. TIMS vs In-situ SIMS U-Pb dating. TIMS : Highest precision (0.1%)

eamon
Download Presentation

In-situ SIMS U-Pb dating of Wyoming and Siberian dikes

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. In-situ SIMS U-Pb dating of Wyoming and Siberian dikes Presentation for CAMIRO Project 08E03 ‘Reconstruction of supercontinents back to 2.7 Ga’ Project meeting March 3, 2012 Kevin Chamberlain, University of Wyoming

  2. TIMS vs In-situ SIMS U-Pb dating TIMS: • Highest precision (0.1%) • Reliable Pb/Pb and U/Pb dates • Grain sizes ≥20 microns SIMS: • Reliable Pb/Pb (1%), less so U/Pb dates • Textural settings preserved • Both primary and metamorphic dates • Grain sizes 3 to 40 microns

  3. 50 micron scale (10 micron increments) 2010

  4. Caribbean basalt Curacao: Bd = 115 Ma Zir = 80 Ma

  5. Zr Bd 20 µm

  6. Micro-baddeleyite: preliminary results • baddeleyite from Sette Daban (N Siberia) • mafic sills within carbonate platform sequence • analyzed grains between 30 and 10 mm (short dimension), depth resolution ~1-2 mm

  7. SIMS baddeleyite discordance problem A56 EQ98-0710 Timptano swarm Aldan shield, 1750-1710 Ma

  8. SIMS baddeleyite discordance problem

  9. SIMS baddeleyite discordance problem Pb/Pb: 1750 Ma UI: 1713 Ma 250 Ma zircon & Siberian traps

  10. SIMS baddeleyite discordance problem Pb/Pb: 1750 Ma UI: 1713 Ma TIMS: 1750 Ma 250 Ma zircon & Siberian traps

  11. SIMS baddeleyite discordance problem New calibration New calibration

  12. In-situ SIMS U-Pb dating projects-Leeward Antilles Bonaire: Bd = 112 Ma Zir = 93 Ma Aruba: Bd = 102 Ma Zir = 97 Ma Curacao: Bd = 115 Ma Zir = 80 Ma Los Rocas: Zir = 87 Ma PI: Jim Wright, University of Georgia

  13. New Results • Caribbean and HALIP targets identified • Siberia: two new events, 1470 & 1030 Ma • Wyoming: better ties to Kaapvaal, ca. 2.7 Ga

  14. Caribbean basalt BSE scan and dating targets Red=baddeleyite Purple=zircon

  15. New Siberian results from SIMS work Anabar Shield: A89 1466±14 Ma Sette Daban: 1033±34 Ma

  16. Wyoming dike locations New result Beartooth Mts: 2718±34 Ma

  17. Bighorn sample results New results: Leopard dike 2700±9 Ma Previous results: A60-61: 2715 Ma A49: 2690 Ma A25-27: 2155 Ma A32: 1900 Ma 1965±27 Ma 2670±5 Ma (Bd & zr)

  18. Kaapvaal-Wyoming Connection ca. 2.7 Ga? Common dike ages: 2720 Ma 2700 Ma 2690 Ma 2670 Ma

More Related