Post-glacial microbialite formation in coral reefs of the Pacific, Atlantic, and Indian Oceans

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doi: 10.1016/j.chemgeo.2012.02.009
Author(s): Heindel, Katrin; Birgel, Daniel; Brunner, Benjamin; Thiel, Volker; Westphal, Hildegard; Gischler, Eberhard; Ziegenbalg, Simone B.; Cabioch, Guy; Sjovall, Peter; Peckmann, Jörn
Author Affiliation(s): Primary:
University of Bremen, Center for Marine Environmental Sciences, Bremen, Germany
University of Vienna, Austria
Max Planck Institute of Marine Microbiology, Germany
Georg August University Gottingen, Germany
Leibniz Center for Tropical Marine Ecology, Germany
Goethe University, Germany
Institute of Research for Development, France
Swedish National Testing and Research Institute, Sweden
Volume Title: Chemical Geology
Source: Chemical Geology, Vol.304-305, p.117-130. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541 CODEN: CHGEAD
Note: In English. 102 refs.; illus., incl. 2 tables, sketch map
Summary: The occurrence of microbialites in post-glacial coral reefs has been interpreted to reflect an ecosystem response to environmental change. The greater thickness of microbialites in reefs with a volcanic hinterland compared to thinner microbial crusts in reefs with a non-volcanic hinterland led to the suggestion that fertilization of the reefal environment by chemical weathering of volcanic rocks stimulated primary productivity and microbialite formation. Using a molecular and isotopic approach on reef-microbialites from Tahiti (Pacific Ocean), it was recently shown that sulfate-reducing bacteria favored the formation of microbial carbonates. To test if similar mechanisms induced microbialite formation in other reefs as well, the Tahitian microbialites are compared with similar microbialites from coral reefs off Vanuatu (Pacific Ocean), Belize (Caribbean Sea, Atlantic Ocean), and the Maldives (Indian Ocean) in this study. The selected study sites cover a wide range of geological settings, reflecting variable input and composition of detritus. The new lipid biomarker data and stable sulfur isotope results confirm that sulfate-reducing bacteria played an intrinsic role in the precipitation of microbial carbonate at all study sites, irrespective of the geological setting. Abundant biomarkers indicative of sulfate reducers include a variety of terminally-branched and mid chain-branched fatty acids as well as mono-O-alkyl glycerol ethers. Isotope evidence for bacterial sulfate reduction is represented by low δ34S values of pyrite (-43 to -42 ppm) enclosed in the microbialites and, compared to seawater sulfate, slightly elevated δ34S and δ18O values of carbonate-associated sulfate (21.9 to 22.2 ppm and 11.3 to 12.4 ppm, respectively). Microbialite formation took place in anoxic micro-environments, which presumably developed through the fertilization of the reef environment and the resultant accumulation of organic matter including bacterial extracellular polymeric substances (EPS), coral mucus, and marine snow in cavities within the coral framework. ToF-SIMS analysis reveals that the dark layers of laminated microbialites are enriched in carbohydrates, which are common constituents of EPS and coral mucus. These results support the hypothesis that bacterial degradation of EPS and coral mucus within microbial mats favored carbonate precipitation. Because reefal microbialites formed by similar processes in very different geological settings, this comparative study suggests that a volcanic hinterland is not required for microbialite growth. Yet, detrital input derived from the weathering of volcanic rocks appears to be a natural fertilizer, being conductive for the growth of microbial mats, which fosters the development of particularly abundant and thick microbial crusts. Abstract Copyright (2012) Elsevier, B.V.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 06 Petrology, Sedimentary; Anthozoa; Atlantic Ocean; Atolls; Bacteria; Belize; Biochemistry; Biogenic processes; Carbohydrates; Carbonate rocks; Central America; Cnidaria; Degradation; East Pacific; Ethers; Expedition 310; French Polynesia; Indian Ocean; Indian Ocean Islands; Integrated Ocean Drilling Program; Invertebrata; Ion probe data; Isotope ratios; Isotopes; Limestone; Maldive Islands; Marine environment; Mass spectra; Melanesia; Microbialite; O-18/O-16; Oceania; Organic compounds; Oxygen; Pacific Ocean; Polynesia; Postglacial environment; Reefs; S-34/S-32; Sedimentary rocks; Society Islands; South Pacific; Southeast Pacific; Spectra; Stable isotopes; Sulfur; Tahiti; Tahiti Sea Level Expedition; Vanuatu
Coordinates: S180000 S170000 W1490000 W1500000
Record ID: 2012067274
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands