Diversity of Bahamian Microbialite Substrates
Diversity of Bahamian Microbialite Substrates
复制标题
巴哈马微生物岩基质的多样性
DOI：
10.1007/978-1-4020-8306-8_6
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发表时间：
2008
影响因子：
5.3
通讯作者：
N. Planavsky
中科院分区：
文献类型：
--
作者：
R. Ginsburg;N. Planavsky
叠层石，石灰石和白云石的层状柱状和分支结构，是地球历史上最初数十亿年生命的唯一宏观证据。这些有机沉积构造是前寒武纪碳酸盐岩序列的重要组成部分，零星分布于显生宙。它们是金属矿石的宿主，也是碳氢化合物的储集岩。仍然活着的巴哈马柱状结构与古代微生物岩(叠层岩和血栓岩)相对应，提供了一个特殊的机会来检查它们的底物是否在确定这些非凡结构的产状和模式中发挥了作用。巴哈马叠层石的蓝藻建造者可以在几乎所有的基质上定居，除了流动的沙子。然而，具有显著浮雕的柱状结构的发展需要坚硬或坚固的衬底。从已发表的关于基质的报告和我们自己的观察中，我们认识到两类基质：继承性的，由预先存在的岩石表面组成；可再生的，包括所有在积累过程中可以重复发展的基质。巴哈马继承的底物包括更新世石灰岩，带有或不带有钙质或古土壤的复层结壳。海洋环境中的可再生底物包括同沉积硬质生物、珊瑚和软体动物的大骨架、珊瑚藻类或蠕虫腹足类的结壳，以及细粒碳酸盐沉积物的坚固地面。认识到可再生底物在确定现代巴哈马标本产状和年龄变化方面的关键作用，强调在今后的研究中需要更多地注意微生物的基础。
Stromatolites, laminated columnar and branched structures of limestone and dolomite, are the only macroscopic evidence of life for the first few billion years of earth history. These organo-sedimentary structures are a prominent constituent of Precambrian carbonate successions and occur sporadically throughout the Phanerozoic. They are hosts for metallic ores and serve as reservoir rocks for hydrocarbons. Still living Bahamian columnar forms that are counterparts of ancient microbialites (stromatolitic and thrombolitic) provide a special opportunity to examine if their substrates played a role in determining the occurrences and patterns of these remarkable structures. The cyanobacterial builders of Bahamian stromatolites can colonize almost all substrates except mobile sands. The development of columnar structures with significant relief however, requires either a hard or firm substrate. From published reports on substrates and our own observations we recognize two families of substrates: inherited, consisting of pre-existing rock surfaces and renewable, including all substrates that can develop repeatedly during accumulation. Inherited substrates in the Bahamas include Pleistocene limestone with or without palimpsest encrustations of caliche or paleosol. Renewable substrates in the marine environment include syndepositional hardgrouds, large skeletons of corals and mollusks, encrustations of coralline algae or vermetid gastropods, and firm grounds of fine-grained carbonate sediment. Recognizing the key roles of renewable substrates in determining the occurrences and age variations of modern Bahamian specimens emphasizes the need for increased attention to the foundations of microbialites in future studies.