CALL FOR PROPOSALS:

ORGANIZERS

  • Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC

 

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Paper No. 3
Presentation Time: 9:00 AM-6:00 PM

THE ORIGIN AND SIGNIFICANCE OF EDIACARAN BARITE IN MONGOLIA


BOLD, Uyanga1, MACDONALD, Francis A.2, JOHNSTON, David T.1, WING, Boswell3, HOFFMAN, Paul4 and SMITH, Emily F.5, (1)Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, (2)Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, (3)Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, QC H3A 2A7, Canada, (4)Earth & Planetary Sciences, Harvard Univ, 20 Oxford St, Cambridge, MA 02138, (5)Earth and Planetary Science, Harvard University, 20 Oxford Street, Cambridge, MA 02138, ubold@fas.harvard.edu

The Zavkhan (Dzabkhan) basin of southwestern Mongolia hosts multiple Neoproterozoic glacial deposits within carbonate-dominated strata of the Tsagaan Olom Formation.

Here we report the discovery of sedimentary barite fans (BaSO4) and barite breccias in the Ol cap carbonate and barite breccias in the underlying Upper Tayshir member in Zavkhan basin. These barites are most probably related to a dolomitization effect.

Barite fans were discovered at the mountain pass, Hoh Davaa. Barites are bedded, composing fans, domal structures, and breccias. Here, the Upper Tayshir carbonates are light grey in color and have a gritty dolomitization with visible barite breccias.

Samples were collected for carbon and oxygen isotope analyses in multiple sections across the basin spanning over 100 km. Large lateral gradients are present in carbon isotope profiles of the Ol cap carbonate. In the eastern portion of the basin, carbon isotope data display sigmoidal profiles with a nadir at -6‰, similar to other cap carbonates around the world (Hoffman & Schrag, 2002). However, in the westernmost sections, carbon isotope values are extremely enriched with few negative values and a peak at ~+8‰. The most isotopically enriched sections are the ones with barites and a dolomitization effect.

Session No. 101--Booth# 149

Precambrian Geology (Posters)
Monday, 10 October 2011: 9:00 AM-6:00 PM
Hall C (Minneapolis Convention Center)
Geological Society of America Abstracts with Programs. Vol. 43, No. 5, p.269
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