神农架世界地质公园中元古代巨型叠层石

摘要

The giant stromatolites have been found in dolostones of Mesoproterozoic Kuangshishan and Taizi formations (1 215-1 459Ma) in the Shennongjia UNESCO Global Geopark,Central China.These enormous elongate domal stromatolites,which can usually be 2-10 m wide and high,and several meters or dozens of meters long,developed in subtidal conditions on a carbonate platform related to a marine transgression,where was rich in Si,Mn and Fe from submarine volcanism.A new species and genus,Megadomia shennongjiaensis,is proposed for this impressive macrofossil,which is morphologically similar to the huge stromatolites from Neoarchean Tumbiana Formation in Australia (ca.2 724 Ma),Paleoproterozoic Malmani Dolomite in South Africa (ca.2 250 Ma),and Permian Irati Formation in Brazil (the time interval of 278.4-275.6 Ma).It is suggested that the huge stromatolites would form in a similar specific habitat in different geologic eras.%华中神农架世界地质公园的中元古代矿石山组—台子组白云岩地层(1 215～1 459 Ma)发现巨型叠层石.这些宽度和高度通常为2～10m、长度可达数十米的穹状叠层石发育在碳酸盐台地上与海侵作用有关的潮下带环境,受到海底火山活动影响,处于硅和铁-锰含量偏高的海水中.根据这些巨型叠层石的特征,命名它们为神农架大圆顶叠层石(新属、新种)Megadomia shennongjiaensis gen.and sp.nov..其形态与澳大利亚新太古代图姆比亚纳组(Tumbiana Formation,约2 724 Ma)、南非古元古代马尔马尼白云岩(Malmani Dolomite,约2 250 Ma)和巴西二叠纪伊拉蒂组(Irati Formation,278.4～275.6 Ma)的巨型叠层石相似,而且它们的岩性特征也相似,暗示在不同的地质时代,只要出现某—特定的生态环境,就可能形成相似的巨型叠层石.