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Norian vegetation history and related environmental changes; new data from the Chinle Formation, Petrified Forest National Park (Arizona, SW USA)

Viktoria Baranyi, Tammo Reichgelt, Paul E. Olsen, William G. Parker and Wolfram M. Kurschner
Norian vegetation history and related environmental changes; new data from the Chinle Formation, Petrified Forest National Park (Arizona, SW USA)
Geological Society of America Bulletin (October 2017) 130 (5-6): 775-795

Abstract

Fossil plant assemblages including spores and pollen grains provide useful information on past ecosystems and the response of terrestrial biotas to various environmental perturbations. New quantitative palynological data from the Chinle Formation of the American Southwest suggest that a floral turnover occurred in the middle Norian (between 217 and 213 Ma). Analysis of plant communities reveals that this turnover was followed by a complete reorganization of the riparian vegetation, driven by changes in fluvial styles and the tectonic regime of the basin, as well as a gradual transition toward a more arid climate. Marked increases in Klausipollenites gouldii, Patinasporites spp., and Froelichsporites traversei are probable indicators of environmental stress, such as increased aridity, perturbations of atmospheric pCO2, acid rain, and atmospheric aerosol accumulation due to volcanism in connection with the Pangean rifting and uplift of the Cordilleran arc. Comparison of the vegetation turnover with younger assemblages from the Chinle Formation in New Mexico revealed similar floral turnover patterns, suggesting two distinct drier periods as a result of multiple climatic oscillations. The climate-induced floral turnover may have contributed to the vertebrate faunal turnover as the loss of wetland habitat space and an increase in xerophytic plants may have dwindled the supply of palatable vegetation for herbivores. The onset of the floral turnover in Arizona roughly corresponds to the Manicouagan impact event, but a direct causal link is still speculative.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 130
Serial Issue: 5-6
Title: Norian vegetation history and related environmental changes; new data from the Chinle Formation, Petrified Forest National Park (Arizona, SW USA)
Affiliation: University of Olso, Department of Geosciences, Oslo, Norway
Pages: 775-795
Published: 20171019
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 134
Accession Number: 2018-024479
Categories: StratigraphyPaleobotany
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2017345
Illustration Description: illus. incl. strat. col., 2 tables, geol. sketch map
N34°46'60" - N35°10'00", W109°55'00" - W109°46'60"
Secondary Affiliation: Lamont-Doherty Earth Observatory, USA, United StatesPetrified Forest National Park, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute.
Update Code: 201813
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