Hells Bells - mikrobiell generierte Unterwasserspeleotheme aus Yucatan, Mexiko
Zusammenfassung der Projektergebnisse
Unique conical, mantle-shaped downward expanding and diverging calcareous structures, here termed Hells Bells, were recently discovered in the deep meromictic sinkhole (cenote) “El Zapote” and five other cenotes restricted to a small area of the North-Eastern Yucatán Peninsula, Mexico. They are characterized by bell- or trumpet shaped longitudinal and circular, elliptical or horse-shoe-like horizontal cross-sections. Calcite precipitation or growth of Hells Bells is promoted by biogeochemical processes within the aphotic pelagic redoxcline above a sulfidic halocline. There, proton-consuming chemolithoautotrophy and an incomplete microbial oxidation of sulfide increase the pH of the surrounding water inducing calcite oversaturation and precipitation. In order to advance the understanding of Hells Bells formation and to unravel the controls on microbially-induced authigenic calcite precipitation in pelagic redoxclines, we thoroughly investigated the water bodies of deep meromictic cenotes with Hells Bells (El Zapote, Tortugas, Maravilla) in comparison to a similar deepstratified cenote without Hells Bells (Angelita). Stagnancy, or a low degree of convection within the water bodies, is determined to be the dominant factor for the development of biogeochemical conditions; it regulates the fluxes of electron donors and acceptors towards the pelagic redoxcline. Authigenic calcite precipitation occurs only in oxygen or electron acceptor-limited pelagic redoxclines where proton-consuming biogeochemical processes predominate, i.e. incomplete oxidation of sulfide to zerovalent sulfur. Furthermore, a low degree of advection is required in order to create an accumulation of hydrogen carbonate (HCO3-) in the halocline, derived from organic matter degradation. This results in an upward flux of HCO3- towards the redoxcline, where it fuels chemolithoautotrophy and increases calcite saturation. U-series dating indicate underwater growth of Hells Bells was approx.. continuous from ~12.5 ka BP to recent times, while the oldest samples of Hells Bells date back to a period between ~90–120ka BP. Thus, Hells Bells are the largest known underwater speleothems worldwide and are actively growing. http://www.innovations-report.de/html/berichte/geowissenschaften/heidelberger-forscher-untersuchen-einzigartige-unterwasser-tropfsteine.html http://www.scinexx.de/wissen-aktuell-22136-2017-11-27.html http://latina-press.com/news/244445-heidelberger-forscher-untersuchen-einzigartige-unterwasser-tropfsteine/ http://www.natur.de/de/20/Dem-Geheimnis-der-Hoellenglocken-auf-der-Spur,1,,2396.html?tid=2 https://www.n-tv.de/wissen/Unterwasser-Tropfsteine-geben-Raetsel-auf-article20153413.html https://www.derstandard.de/story/2000068592101/die-raetsel-der-hells-bells-von-yucatan http://www.geologypage.com/2017/11/unique-underwater-stalactites.html http://www.echo-online.de/vermischtes/wissenschaft/das-wachstum-der-hoellenglocken_18352469.htm https://www.pravda-tv.com/2017/12/die-raetsel-der-hells-bells-hoehlen-von-yucatan-in-mexiko-video/ https://theworldnews.net/at-news/naturwunder-die-ratsel-der-hells-bells-von-yucatan https://www.portail-de-la-gratuite.com/presse/presse-scientifique/alphagalileo/ http://www.spiegel.de/wissenschaft/natur/mexiko-unterwasser-tropfsteine-die-hoellenglocken-von-el-zapote-a-1182049.html http://conacytprensa.mx/index.php/ciencia/ambiente/19647-campanas-instituto-de-la-prehistoria-de-america-minerales-cuevas
Projektbezogene Publikationen (Auswahl)
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(2017): Hells Bells – unique speleothems from the Yucatán Peninsula, Mexico, generated under highly specific subaquatic conditions, Palaeogeography Palaeoclimatology Palaeoecology, 489, p. 209–229
Stinnesbeck, W., Frey, E., Zell, P., Avilés, J., Hering, F., Frank, N., Arps, J., Geenen, A., Gescher, J., Isenbeck- Schröter, M., Ritter, S., Stinnesbeck, S., Núñez, E. A., Dahne, V. F., González, A. G. and Deininger, M.
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(2018): Erforschen eines Cenotes in Mexiko mit einer Multisonde, Wasserwirtschaft, Nov, 2018
Ritter, S. M. and Scholz, C.
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(2019): Hells Bells – underwater speleothems, in Goldschmidt Abstracts, p. 2836
Ritter, S. M., Isenbeck-Schröter, M., Scholz, C., Klose, L., Schorndorf, N. and Stinnesbeck, W.
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(2019): Hells Bells – underwater speleothems: A novel paleohydrological archive for the Yucatán Peninsula, Mexico, in Goldschmidt Abstracts, p. 3015
Schorndorf, N., Ritter, S. M., Frank, N., Klose, L. and Stinnesbeck, W.
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(2019): Subaqueous speleothems (Hells Bells) formed by the interplay of pelagic redoxcline biogeochemistry and specific hydraulic conditions in the El Zapote sinkhole, Yucatán Peninsula, Mexico, Biogeosciences, 16(11), p. 2285–2305
Ritter, S. M., Isenbeck-Schröter, M., Scholz, C., Keppler, F., Gescher, J., Klose, L., Schorndorf, N., Avilés Olguín, J., González-González, A. and Stinnesbeck, W.
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(2020): Unravelling the formation of Hells Bells: underwater speleothems from the Yucatán Peninsula in Mexico, Dissertation, Heidelberg University, Germany, pp. 149
Ritter, S. M.
