Cryptozoon and Associate Stromatolites from the Recent, Shark Bay, Western Australia

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.…”

“…Predominance of alternating lamination distinguishes Leza coarse grained stromatolites from most recent examples of coarse-grained car bonate stromatolites, which generally lack thick micrite-rich laminae (Logan, 1961;Dill et al, 1986;Reid et al, 1995Reid et al, , 2000Feldmann and McKenzie, 1998). Planavsky and Ginsburg (2009) describe four succes sive processes responsible for the development of Bahamian microbialites: "1) sediment trapping, binding and initial lithification; 2) disruption and truncation of the initial fabric; 3) pervasive cementa tion and clot formation; and 4) late-stage boring".…”

“…Early studies of present-day stromatolites and other laminated microbial deposits, such as oncoids, related layering to seasonal variations in growth and calcification (Roddy, 1915) and to the size of trapped grains and alterna tion of sediment-rich and organic-rich layers (Black, 1933). Subsequent work has supported and extended this view, and it is now widely ac cepted that primary lamination reflects episodic, in some cases iterative, changes in accretion variously related to variations in microbial growth and calcification, inorganic precipitation, and grain trapping (e. g., Cloud, 1942;Ginsburg and Lowenstam, 1958;Logan, 1961;Hofmann, 1973, � Thrust � Areas with � Leza Fm outcrops 3'W known examples of coarse-grained carbonate stromatolites, and these are unusual in exhibiting both of the lamination styles defined by Monty (1976). Co-occurrence of these contrasting lamination styles sheds light on their processes of formation.…”

Specific carbonate–microbe interactions in the modern microbialites of Lake Alchichica (Mexico)

“…They can be laminated in the case of stromatolites. Although abundant in the Precambrian, microbialites are scarce today, being found only in restricted areas such as in the hypersaline Shark Bay in Australia (Logan, 1961) and in alkaline lakes such as Lake Van in Turkey (Kempe et al, 1991) or Lake Satonda in Indonesia (Arp et al, 2003). The stromatolites from the Bahamas are the only example of such structures developing in an open marine environment (Dravis, 1983;Dill et al, 1986;Reid and Browne, 1991;Reid et al, 2000Reid et al, , 2003.…”

Pattern formation in stromatolites: insights from mathematical modelling

“…By this, we mean the issue of ascertaining the way in which the threedimensional topographies and textures of these rock structures are built up. Modern stromatolites provide the only dynamic models available for experimentation [28][29][30][31]. Such limitations emphasize the importance of insights gained from mathematical models of stromatolite morphogenesis.…”