SILICIFICATION OF HIGHER PLANTS IN GEOTHERMALLY INFLUENCED WETLANDS:YELLOWSTONE AS A LOWER DEVONIAN RHYNIE ANALOG

Channing, Alan; Edwards, Dianne

Silicification of higher plants associated with active, alkali-chloride hotsprings in Yellowstone National Park, Wyoming, USA, occurs dominantlyin areas of geothermally influenced wetlands. Plants grow in anenvironment with many of the characteristics of an oligosaline marsh andare subjected to brackish salinity and high pH, temperature, silica, andheavy metal concentrations. As such, the plants undergoing silicificationat Yellowstone are predominantly those more typically found colonizingwidespread evaporation-driven inland waters and coastal salt marshes(e.g., Eleocharis rostellata, Triglochin maritimum) and are in some wayspreadapted to hot-spring settings. This paper documents hydrochemistryand physical parameters in a typical geothermally influenced wetland atBig Blue Hot Spring, Elk Park in Yellowstone and records thetaphonomic processes involved in silicification of the most commonwetland plant Eleocharis rostellata. Silicification of plants in situ resultsin the three-dimensional preservation of tissues and cells characteristic ofplants preserved around the Lower Devonian Rhynie chert hot-springsystem. Sinter deposition at active and fossil hot-spring areas is typicallyassociated with alkali-chloride springs above low-sulfidation epithermalsystems. As mineralogical and geological evidence indicates that such asystem was responsible for preservation of the Rhynie plants, it ishypothesized that they too, at least periodically, withstood comparablephysiological stresses to the modern analogs.

SILICIFICATION OF HIGHER PLANTS IN GEOTHERMALLY INFLUENCED WETLANDS:YELLOWSTONE AS A LOWER DEVONIAN RHYNIE ANALOG

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