40Ar/39Ar dating of ignimbrite from Inner Mongolia, northeastern China, indicates a post-Middle Jurassic age for the overlying Daohugou Bed
Abstract
The 40Ar/39Ar step heating analyses of K-feldspar derived from the ignimbrite in Inner Mongolia, China indicates that they were formed at 159.8 +/- 0.8 Ma, which provides a maximum age for the overlying fossil-bearing lacustrine deposits (Daohugou Bed). This result favors a post-Middle Jurassic (Late Jurassic or younger), rather than the Middle Jurassic age for the Daohugou Bed. Such a result is generally consistent with vertebrate biostratigraphic evidence, providing a maximum known age for the first appearance of several major animal groups such as Cryptobranchidae of Urodela (salamanders) and Maniraptora (birds and their closest dinosaurian relatives).
- Publication:
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Geophysical Research Letters
- Pub Date:
- October 2004
- DOI:
- 10.1029/2004GL020792
- Bibcode:
- 2004GeoRL..3120609H
- Keywords:
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- Geochemistry: Geochronology;
- Volcanology: Ash deposits;
- Information Related to Geographic Region: Asia;
- Information Related to Geologic Time: Mesozoic