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Paleoenvironmental reconstruction of Jurassic dinosaur habitats of the Vega Formation, Asturias, Spain

Karen Gutierrez and Nathan D. Sheldon
Paleoenvironmental reconstruction of Jurassic dinosaur habitats of the Vega Formation, Asturias, Spain
Geological Society of America Bulletin (November 2011) 124 (3-4): 596-610


Jurassic-aged strata of Asturias, Spain, contain trace fossils including sauropod, theropod, and ornithopod dinosaur footprints, but their paleoenvironmental context has been relatively unstudied. A coastally exposed continuous section at Playa de Vega shows a clear transition from the marine Middle Jurassic Rodiles Formation to the terrestrial Upper Jurassic Vega Formation. Within the >100 m of Vega Formation stratigraphy that was logged there, four distinct types of paleosols were identified: (1) Entisols, (2) Inceptisols, (3) Vertisols, and (4) composite or cumulative paleosols. The paleosol types and their features indicate a floodplain depositional setting with short stature, shrubby vegetation. Theropod and ornithopod tracks have been identified at the base of the section, indicating that a dinosaurian fauna was present at Playa de Vega during the Jurassic. Results from well-characterized climofunctions based on modern soils and paleosol B horizon chemical composition of the Inceptisols and Vertisols yield mean annual precipitation estimates of 400-980 mm yr (super -1) and mean annual temperature estimates of 8-15 degrees C. The presence of Vertisols, with both evidence for shrink-and-swell behavior and dispersed pedogenic carbonate, is consistent with a strongly seasonal precipitation regime. The delta (super 13) C analyses of pedogenic carbonates yield values that range from -7.09 per mil to -8.88 per mil (relative to Vienna Peedee belemnite [VPDB]) and indicate carbon dioxide levels about six times pre-industrial levels, consistent with previous results. The Asturian vertebrate track assemblage is remarkably similar to that of the Morrison Formation (western United States), but it has greater overall richness. The pattern is reversed for body fossils. The reconstructed paleoenvironmental and paleoclimatic conditions indicate similar depositional settings in both places, but with a cooler, wetter, more seasonal environment in Asturias. The greater seasonality indicated by the Vega Formation relative to the Morrison Formation may explain the observed differences in richness.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 124
Serial Issue: 3-4
Title: Paleoenvironmental reconstruction of Jurassic dinosaur habitats of the Vega Formation, Asturias, Spain
Affiliation: University of Michigan, Department of Geological Sciences, Ann Arbor, MI, United States
Pages: 596-610
Published: 20111101
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 67
Accession Number: 2012-016185
Categories: StratigraphySedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2011327
Illustration Description: illus. incl. 3 tables, sketch map
N43°28'57" - N43°28'57", W05°07'54" - W05°07'54"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201209
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