1 / 12

In-situ SIMS U-Pb dating of Caribbean basalts and lavas

In-situ SIMS U-Pb dating of Caribbean basalts and lavas. Presentation for CAMIRO Project 08E03 ‘Reconstruction of supercontinents back to 2.7 Ga’ Project meeting March 5, 2011 Kevin Chamberlain, University of Wyoming. In-situ SIMS U-Pb dating.

leroy
Download Presentation

In-situ SIMS U-Pb dating of Caribbean basalts and lavas

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 Caribbean basalts and lavas Presentation for CAMIRO Project 08E03 ‘Reconstruction of supercontinents back to 2.7 Ga’ Project meeting March 5, 2011 Kevin Chamberlain, University of Wyoming

  2. In-situ SIMS U-Pb dating • U-Pb minerals survive alteration better than many Ar-Ar targets • In-situ can date baddeleyite and zircon grains as small as 3 microns--undateable by other methods • Textural settings preserved • Can resolve both primary and metamorphic dates • Age Precisions of 5% or better

  3. Magmatic z ~130 Ma Def. z 90 Ma

  4. Recent U-Pb dating projects-Leeward Antilles and Tobago Tobago North Coast schist & San Souci fm. Magmatic & metamorphic ages. Pis: Art Snoke, Univ. WY Andrew Kerr & Iain Neill, Cardiff Leeward Antilles Aruba, Curacao, Bonaire, Los Rocas test of Caribbean-Columbia Oceanic Plateau PI: Jim Wright, University of Georgia

  5. Recent U-Pb dating projects-Leeward Antilles and Tobago Tobago North Coast schist & San Souci fm. Magmatic & metamorphic ages. Pis: Art Snoke, Univ. WY Andrew Kerr & Iain Neill, Cardiff Aruba: Bd = 102 Ma Zir = 97 Ma Curacao: Bd = 115 Ma Zir = 80 Ma Bonaire: Bd = 112 Ma Zir = 93 Ma Los Rocas: Zir = 87 Ma Leeward Antilles Aruba, Curacao, Bonaire, Los Rocas test of Caribbean-Columbia Oceanic Plateau PI: Jim Wright, University of Georgia

  6. SIMS baddeleyite and zircon data-produced March 4, 2011-San Souci sample

  7. Cretaceous Oceanic Plateaus – potential U-Pb dating targets Prepared by Andrew Kerr, Cardiff The Shatsky Rise likely formed around Jur-Cret boundary – but only 1 Ar-Ar date - samples from 2009 IODP leg are now available to all workers - There is scope for U-Pb dating given potential links to Tithonian black shales • Drilled Ontong Java • Plateau sections are • poorly dated – only • Ar-Ar from the 1990s • the validity of the 90Ma • Ar-Ar age (site 803) • questioned by many. • given potential links to • anoxia and black shales • at ~122 and 93Ma, • new U-Pb dating is well • worthwhile There are only 3 Ar-Ar dates for the 105-90Ma parts of Kerguelen Plateau (and one has quite a disturbed Ar-Ar plateau) - the volume of magma emplaced in this time period on the KP was of the order of 9 million km3 - so this event could have contributed significantly to global anoxia and consequent black shale formation – more (U-Pb) dating is clearly warranted. Drilled Caribbean plateau see next slide

  8. Proto-Caribbean Oceanic Plateau – U-Pb dating targets These fragments are mid-late Cretaceous but formed within the Caribbean – not in the Pacific like the main CCOP. They are potentially significant in the maturation of hydrocarbon reservoir rocks Margot Fm. basalts ~ 120-100Ma by paleo Duarte Fm. basalts ~90Ma – by Ar-Ar but ages are disputed Sans Souci Fm. basalts & gabbros Being dated by Kevin Expected age 120-100Ma El Copey Fm. basalts with Kevin for assessment for U-Pb dating Expected age 120-100Ma Siquisique Fm. basalts & gabbros with Kevin for assessment for U-Pb dating. Dated by Ar-Ar to 90-95 Ma but spectra quite disturbed. Other nearby exposures have recently been identified and will be mapped and sampled in detail later this year.

  9. Caribbean-Colombian Oceanic Plateau – U-Pb dating targets These fragments of the CCOP are notoriously difficult to date by Ar-Ar (too altered) Western Cordillera of Colombia/Ecuador. Only a handful of Ar-Ar ages (some quite disturbed plateaus) from throughout the entire length of this ~1000km- long sequence. Most are 95-85Ma, but there are younger ~75Ma dates. U-Pb dates from a selected set of samples from the N to the S of the Cordillera (the most extensive continuous sequence in the province) is likely to more rigorously constrain the timing of the CCOP Other Caribbean targets: ROV samples of Beata Ridge Panama Dominican Republic Aruba (in hand-Jim Wright) Curacao (In hand-Jim Wright)

More Related