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Affect of Sedimentation on Stromatolite Reef Growth and Morphology, Ediacaran Omkyk Member (Nama Group), Namibia

Johnson, J. and Grotzinger, J. P. (2006) Affect of Sedimentation on Stromatolite Reef Growth and Morphology, Ediacaran Omkyk Member (Nama Group), Namibia. South African Journal of Geology, 109 (1-2). pp. 87-96. ISSN 1012-0750. doi:10.2113/gssajg.109.1-2.87.

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Superbly preserved reefs of Ediacaran age in Namibia give clues to environmental controls on stromatolite-thrombolite growth morphology and nucleation. Digital mapping and Measured stratigraphic sections reveal parasequences featuring meter-scale alternation of shallow marine shale and stromatolitic-thrombolitic microbialites associated with other clastic carbonates (grainstones, mudstones). Stromatolite-thrombolite column width, spacing and height vary systematically with the type of sediment being deposited, with growth inhibited during shale deposition. Columns are generally wider and more closely spaced during carbonate sediment deposition and narrower and more widely spaced during shale deposition. While stromatolite growth should be sensitive to sediment type explicitly, we also interpret sediment type as a general proxy for changing environmental conditions (e.g. water depth, turbidity) that may directly affect reef growth. A simple rule-based numerical simulation of microbialite growth is formulated based on the field interpretations of sedimentological and topographic growth controls. The model cannot explain detailed morphologic attributes, but can recreate correlations between stromatolite column widths, column spacing and layer bed thickness as a function of sediment type.

Item Type:Article
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URLURL TypeDescription DOIArticle
Johnson, J.0000-0001-9808-7172
Grotzinger, J. P.0000-0001-9324-1257
Additional Information:© 2006 Geological Society of South Africa. Editorial handling: J. Gutzmer. Thanks to David Fike, Abdullah Al-Habsy, Rashid Al-Hinai, Issa Al-Mazroui, Hamad Al-Shuaily, Aus Al-Tawil, and Erwin Adams for help and good times in the field. Thanks to Marianne and Rob Field for enthusiastically allowing work on Zebra River farm. Logistical support was provided by the Geological Survey of Namibia. This work was supported by National Science Foundation Grants EAR-9904298 and EAR-0001018, and Petroleum Development Oman. We appreciate thoughtful reviews by K.H. Hofman and N.J. Beukes.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
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Petroleum Development OmanUNSPECIFIED
Issue or Number:1-2
Record Number:CaltechAUTHORS:20130220-135224362
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Official Citation: J. Johnson and J. P. Grotzinger Affect of Sedimentation on Stromatolite Reef Growth and Morphology, Ediacaran Omkyk Member (Nama Group), Namibia South African Journal of Geology, June 2006, v. 109, p. 87-96, doi:10.2113/gssajg.109.1-2.87
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37024
Deposited By: Ruth Sustaita
Deposited On:20 Feb 2013 22:12
Last Modified:09 Nov 2021 23:26

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