A middle–late Ediacaran volcano‐sedimentary record from the eastern Arabian‐Nubian shield |
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| Authors: | David Nettle Galen P. Halverson Grant M. Cox Alan S. Collins Mark Schmitz James Gehling Peter R. Johnson Khalid Kadi |
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| Affiliation: | 1. Tectonics, Resources and Exploration (TRaX), School of Earth and Environmental Sciences, University of Adelaide, , Adelaide, SA, 5005 Australia;2. Department of Earth and Planetary Sciences/Geotop, McGill University, , Montréal, H3A 0E8 Canada;3. Department of Geosciences, Boise State University, , Boise, ID, 83725 USA;4. South Australian Museum, , Adelaide, SA, 5005 Australia;5. Consultant, , Portland, OR, 97219 USA;6. Saudi Geological Survey, , Jiddah, 21514 Saudi Arabia |
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| Abstract: | The Ediacaran Jibalah Group comprises volcano‐sedimentary successions that filled small fault‐bound basins along the NW–SE‐trending Najd fault system in the eastern Arabian‐Nubian Shield. Like several other Jibalah basins, the Antaq basin contains exquisitely preserved sedimentary structures and felsic tuffs, and hence is an excellent candidate for calibrating late Ediacaran Earth history. Shallow‐marine strata from the upper Jibalah Group (Muraykhah Formation) contain a diversity of load structures and intimately related textured organic (microbial) surfaces, along with a fragment of a structure closely resembling an Ediacaran frond fossil and a possible specimen of Aspidella. Interspersed carbonate beds through the Muraykhah Formation record a positive δ13C shift from ?6 to 0‰. U‐Pb zircon geochronology indicates a maximum depositional age of ~570 Ma for the upper Jibalah Group, consistent with previous age estimates. Although this age overlaps with that of the upper Huqf Supergroup in nearby Oman, these sequences were deposited in contrasting tectonic settings on opposite sides of the final suture of the East African Orogen. |
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