Quantifying the oldest tidal record: The 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa

Research Article| September 01, 2000 Quantifying the oldest tidal record: The 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa Kenneth A. Eriksson; Kenneth A. Eriksson 1Department of Geological Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA Search for other works by this author on: GSW Google Scholar Edward L. Simpson Edward L. Simpson 2Department of Physical Sciences, Kutztown University, Kutztown, Pennsylvania 19530, USA Search for other works by this author on: GSW Google Scholar Geology (2000) 28 (9): 831–834. https://doi.org/10.1130/0091-7613(2000)28<831:QTOTRT>2.0.CO;2 Article history received: 25 Feb 2000 rev-recd: 05 Jun 2000 accepted: 20 Jun 2000 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Kenneth A. Eriksson, Edward L. Simpson; Quantifying the oldest tidal record: The 3.2 Ga Moodies Group, Barberton Greenstone Belt, South Africa. Geology 2000;; 28 (9): 831–834. doi: https://doi.org/10.1130/0091-7613(2000)28<831:QTOTRT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The 3.2 Ga Moodies Group in the Barberton Greenstone Belt, South Africa, contains the oldest preserved record of tides. The tidal record is preserved in a tidal sand-wave deposit in the lower Moodies Group as bundles of sandstone foresets separated by mudstone drapes. Detailed analysis of rhythmic foreset bundles permits quantification of the tidal record and reveals a hierarchy of diurnal, fortnightly, and monthly tidal periodicities. Thick-thin pairs of foreset bundles reflect deposition from semidiurnal dominant and subordinate flood-tidal currents, respectively. Cyclic variations in foreset bundle thicknesses record longer period changes in strength of the dominant semidiurnal tidal currents consistent with neap-spring-neap tidal cyclicity. Alternating thicker and thinner neap-spring-neap cycles are comparable to anomalistic, perigean-apogean tidal signatures. This quantitative record of tides in the middle Archean Moodies Group represents, by 2.2 b.y., the oldest such documentation. Tidal cyclicity recognized in the Moodies sand-wave deposit is comparable to that recorded in modern tidal settings and identified in the Carboniferous rock record and is most compatible with a lunar orbital shape similar to that existing today. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.