Hekou Formation

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Hekou Formation
Stratigraphic range: Late Cretaceous, ?Maastrichtian[1]
TypeGeological formation
Unit ofGuifeng Group
UnderliesTangbian Formation
OverliesUnconformity: Zhoutian Formation
Lithology
PrimaryConglomerate, glutenite
OtherSandstone, siltstone, tuff
Location
RegionJiangxi Province, Asia
CountryChina

The Hekou Formation is a Cretaceous geologic formation in China. Pterosaur fossils have been recovered from the formation. It is a unit of the Guifeng Group and dates to the Late Cretaceous.[2] Dinosaur fossils from the formation include a nearly perfect oviraptorid embryo nicknamed Baby Yingliang, an unnamed large hadrosaurid, and hadrosauroid eggs with embryos.[3][4][5] Mammal fossils include Erythrobaatar and Yubaatar qianzhouensis.[6][7] The polyglyphanodontian lizard Yechilacerta has also been described from the formation.[8]

Description

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The Hekou Formation is a constituent of the Guifeng Group; a sequence of formations that were deposited in the Xinjiang Basin including the Hekou, Tangbian, and Lianhe formation which record aeolian-alluvial interactions in a palaeoplateau desert. Both a successional and coeval model of the deposition of these units have been proposed, with estimated ages of the Hekou formation ranging from Coniacian-Santonian to Maastrichtian.[9][10] The associated facies include alluvial fans and adjacent wadi river channels, with mudcracks indicating subaerial exposure of the deposits. Oxygen-18 isotope values recorded in Dinosaur eggshells indicated low annual precipitation and humidity, suggesting an arid to semi-arid environment. The occurrence of striated cobbles in the alluvial facies suggests glacial activity in the catchment areas of the Cretaceous plateau.[11][12]

See also

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References

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