Influences of Storm Erosion and Deposition on Rhythmites of the Upper Wenchang Formation (Upper Ordovician) Around Tonglu, Zhejiang Province, China

Daidu Fan, Congxian Li, Ping Wang

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Abstract

<p> <p id="x-x-x-p-1"> Tonglu rhythmites (Upper Ordovician) in Zhejiang Province, east-central China, display three orders of cyclicity in sandstone and mudstone layer thickness. Millimeter-thick alternations of sandstone and mudstone laminae are ascribed to single tidal cycles. Centimeter-thick alternations of sand-dominated layers (SDLs) and mud-dominated layers (MDLs) are interpreted to be related to alternation of storm and calm weather conditions with a periodicity longer than that forced by neap-spring tidal cyclicity. The SDLs are interpreted as storm deposits on the basis of presence of scour structures, abundant intraformational mud pebbles, oscillation ripples, and thinning-upward trends in the sandstone laminae. A third, meter-thick cycle of variations in sandstone-lamina thickness is interpreted as a reflection of cross-shore changes in coastal dynamics and water depth in the subtidal-intertidal environment. <p id="x-x-x-p-2"> Storm waves, usually considered to be random destructive factors to normal cyclic deposits, are here highlighted as effective agents of sediment transport and deposition of the sand-dominated layers. This study aims at improving our facies-level understanding of the genesis and preservation of storm-related tidal-flat rhythmites on open coasts, and highlights the fact that storm related facies can mimic the cyclicity that is commonly ascribed to neap-spring tidal variation. </p> </p></p>
Original languageAmerican English
JournalJournal of Sedimentary Research
Volume74
DOIs
StatePublished - Jul 1 2004

Disciplines

  • Earth Sciences
  • Geology
  • Physical Sciences and Mathematics

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