Hardened Subtidal Stromatolites, Bahamas

Abstract

Hardened, high-relief stromatolites have been discovered along the margins of some Bahamian platforms. They occur in high-energy (tidal) oolitic sand environments in waters ranging in depth from about 1 to 5 meters. Physical stress produced by actively migrating bed forms of oolitic sand appears to exclude grazing gastropods and subsequent community successions, permitting stromatolite growth.

Origin and significance of lamination in Lower Cretaceous stromatolites and proposal for a quantitative approach

“…This difference in grain-size has been noted in present-day marine coarse-grained carbonate stromato lites formed by stabilisation (trapping and binding) of previously mo bile grains by microbial mats (Logan, 1961;Monty, 1976;Dravis, 1983;Reid and Browne, 1991;Riding et al, 1991a;Reid et al, 1999). In these examples, grain-trapping is produced by erect filaments, mat ir regularities, and extracellular polymeric substances (EPS) secreted by cyanobacteria and other mat microbes (Logan, 1961;Playford and Cockbain, 1976;Dravis, 1983;Dill et al, 1986;Awramik and Riding, 1988;Riding et al, 1991a;Visscher et al, 1998;Reid et al, 2000;Decho et al, 2005;Dupraz et al, 2009;Browne, 2011;Bowlin et al, 2012;jahnert and Collins, 2012). Rare filaments in some mixed laminae of the Leza coarse-grained stromatolites (Fig.…”

“…7B, C) may be relicts of cyanobacteria. Calcified filaments, similarly preserved, also occur rarely in present-day Bahamian examples (Dravis, 1983;Reid and Browne, 1991;Reid et al, 1995;Macintyre et al, 1996;Feldmann and McKenzie, 1998;, and as filament molds at Shark Bay (Reid et aI., 2003).…”

“…Since the thin micritic crusts that define this lamination style are essentially microscopic and often discontinuous and laterally impersistent, the predominance of repetitive lamination in these exam ples helps explain the irregular and crude macrolamination commonly observed in parts of them (Lngan, 1961;Dravis, 1983;Dill et aI., 1986;Planavsky and Ginsburg, 2009), that is also reflected in composite descriptive terminologies such as 'thrombolitic stromatolites' (Aitken, 1967), 'thrombolite/stromatolite domes' (Riding et al, 1991a), or 'coarse-grained thrombolites' (Feldmann, 1995).…”

A Review on Microbialites: a Korean Perspective

“…현생 미생물암 현존하는 해성 미생물암은 주로 오스트레일리아의 샤크만과 바하마에서 보고되었다 (Dravis, 1983;Dill et al, 1986;Reid et al, 1995Reid et al, , 2003Feldmann and McKenzie, 1998;Andres and Reid, 2006;Jahnert and Collins, 2011). 이들은 주로 생쇄설성 또는 어란성 퇴적물을 포함하며, 약한 엽층리 또는 엉김 구조를 형성한다.…”

“…미생물암 에 대한 연구는 Kalkowsky(1908)가 트라이아스기 퇴 적층에서 얇은 엽층으로 이루어지고 위로 볼록한 퇴 적체를 인지하고, 이에 대해 스트로마톨라이트 (stromatolite)라는 용어를 제안하면서 이러한 구조가 미생물에 의해 만들어졌을 것이라고 제시한 데에서 시작되었다 (Paul and Peryt, 2000). 이후 오스트레일 리아의 샤크만(Shark Bay)과 바하마 등에서 현생 미 생물암이 발견되어 이에 대한 연구가 오늘날까지 지 속적으로 이루어지고 있다 (Dravis, 1983;Dill et al, 1986;Moore and Burne, 1994;Reid et al, 1995Reid et al, , 2003Ferris et al, 1997;Feldmann and McKenzie, 1998;Laval et al, 2000;Andres and Reid, 2006;Jahnert and Collins, 2011). 미생물암을 형성하는 미 생물들은 선캄브리아 시대에는 광합성을 통해 다량의 산소를 생성하여 오늘날과 같은 대기를 조성하는 데 크게 기여했으며, 또한 현생 산호초와 유사한 대규모 생물초(biogenic reef)를 형성하는 등 탄산염암의 퇴적 작용에도 깊이 관여하였다 (Riding, 2000;James and Wood, 2010).…”