Sandau, Stephen .
Duchesne River Formation (Late Eocene) Megaflora Preservation by Microflora Algae from the Uinta Basin, Utah.
The Duchesne River Formation (Late Eocene) is known for its paleo fauna yet little is known about the fossil flora of that time. Recently however, isolated and well preserved megaflora structures were discovered in the Brennan Basin Member of the Duchesne River Formation, Uinta Basin, Utah. Preservation was due to the replacement of cellular structures through the precipitation of (CaCO3) by the photosynthetic green algae Chlorellopsis coloniata. A well-preserved three dimensional stem ( Equisetum sp.), comprised of two partial and six complete internodes was discovered. The internodes range in length from 9-20 mm. Seven nodes were preserved and are whorled with branch traces which standout in relief around the nodes. Branch traces are spaced between the ends of the retuse, bilobate leaf traces. Ribs running along the culmacious stem are 26-28 in number and (2 mm) wide. The ribs on the adjoining segments of the stem appear to be offset by half. Well preserved vascular strands run along the length of the internodes numbering approximately 24-28 on the surface. The interior wall of the nodose culm is lined with two algal laminae separated by a thin, inorganic white layer, with a total variable thickness of (1-3 mm). The stem shows signs of pre-depositional and post-depositional deformation. In addition to the equisetale, root-like structures were discovered, encrusted with algal stromatolitic material. Other algae fragments preserved detailed surfaces of the structures they developed on. Of those, a number of wood impressions are preserved showing textures and fiber orientation. A larger elongate stromatolite fragment (49x15 cm) was discovered with a partial bark mold of a mature tree. The deep furrowed and bifurcating pattern is similar to the deciduous angiosperms Populus, Ulmus, or Castanea, all of which in some form have been reported from Eocene formations of the Uinta Basin.
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1 - Intermountain Paleo-Consulting, P. O. Box 1125, 461 West 200 South , Vernal, Utah, 84078, USA
Duchesne River Formation
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM