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Late Triassic charcoal and charcoal-like plant fossils from Petrified Forest National Park, Arizona

Jones, Timothy Peter and Ash, S. R. 2006. Late Triassic charcoal and charcoal-like plant fossils from Petrified Forest National Park, Arizona. In: Parker, W. G., Ash, S. R. and Irmis, R. B. eds. A Century of Research at Petrified Forest National Park: Geology and Paleontology, Museum of Northern Arizona Bulletin, vol. 62. Flagstaff: Museum of Northern Arizona, pp. 106-115.

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Charcoal-like plant fossils, the majority of which appear to be wildfire derived, occur at several different horizons in the lower part of the Chinle Formation of Late Triassic age in Petrified Forest National Park. The most common of these charcoal-like plant fossils are small fragments of black woody material up to1 cm long that are found in situ in the formation. Less commonly, similar small fragments are present on the surface of the formation at two localities where they were left behind as a lag deposit after the enclosing matrix had been removed by erosional processes. Also, charcoal-like material occurs in some of the charred logs and stumps found in the formation. Although there is some small doubt about the taphonomy of some of the material, it is possible that the unusual appearance and low reflectance values of this ‘problematic’ material, may have resulted from later post-burial mineralization of charcoal. The quantitative reflectance values of most of the in situ and reworked fragments ranges from 2.08-3.12% indicating moderate temperature paleowildfires. In contrast, the reflectance results for a charred stump in the Blue Mesa Stump Field of 2.60-2.80% suggests low-temperature in-situ smoldering. Because the phenomenon of smoldering stumps is commonly seen in modern wildfires this locality may represent the remains of an ancient burnt forest.

Item Type: Book Section
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Subjects: Q Science > QE Geology
Uncontrolled Keywords: fossil charcoal, Chinle Formation, Upper Triassic, Petrified Forest National Park, reflected light microscopy, wildfires
Publisher: Museum of Northern Arizona
ISBN: 9780897341202
Last Modified: 09 Apr 2020 15:05

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