Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs
ORIGINAL RESEARCH published: 28 April 2016 doi: 10.3389/feart.2016.00049 Mushroom Speleothems: Stromatolites That Formed in the Absence of Phototrophs Tomaso R. R. Bontognali 1*, Ilenia M. D’Angeli 2*, Nicola Tisato 1, 3, Crisogono Vasconcelos 1, Stefano M. Bernasconi 1, Esteban R. G. Gonzales 4 and Jo De Waele 2, 5 1 Department of Earth Sciences, ETH Zurich, Zurich, Switzerland, 2 Department of Biological, Geological and Environmental Sciences, Bologna University, Bologna, Italy, 3 Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, USA, 4 Comité Espeleológico de Matanzas, Sociedad Espeleológica de Cuba, Matanzas, Cuba, 5 Associazione di Esplorazioni Geografiche la Venta, Treviso, Italy Unusual speleothems resembling giant mushrooms occur in Cueva Grande de Santa Catalina, Cuba. Although these mineral buildups are considered a natural heritage, their composition and formation mechanism remain poorly understood. Here we characterize their morphology and mineralogy and present a model for their genesis. We propose that the mushrooms, which are mainly comprised of calcite and aragonite, formed during four Edited by: different phases within an evolving cave environment. The stipe of the mushroom is an Karim Benzerara, assemblage of three well-known speleothems: a stalagmite surrounded by calcite rafts Centre National de la Recherche Scientifique, France that were subsequently encrusted by cave clouds (mammillaries). More peculiar is the Reviewed by: cap of the mushroom, which is morphologically similar to cerebroid stromatolites and Jakob Zopfi, thrombolites of microbial origin occurring in marine environments. Scanning electron University of Basel, Switzerland microscopy (SEM) investigations of this last unit revealed the presence of fossilized Michal Gradzinski, Jagiellonian University, Poland extracellular polymeric substances (EPS)—the constituents of biofilms and microbial *Correspondence: mats.
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