THE AGE OF THE DINOSAUR-BEARING SEDIMENTS AT TEBCH, INNER-MONGOLIA, PEOPLES-REPUBLIC-OF-CHINA

The coarsening-upward clastic sequence at Tebch, Inner Mongolia, China, containing the dinosaur Psittacosaurus mongoliensis, comprises the remains of a fluviolacustrine system deposited in an extensional tectonic setting. The presence of Asteropollis sp. cf. Asteropollis trichotomosulcatus (Singh) Singh, 1983 in conjunction with the absence of tricolpate pollen indicates a Barremian or possibly early Aptian age. The overlying Tebch basalt, dated by the 40Ar/39Ar laser step-heating method, yields a mid-Aptian age of 110 +/- 0.52 Ma. This chronology supports the argument that the Juifotang Formation of the Jehe Group in western Liaoning is Early Cretaceous, with the Jurassic-Cretaceous boundary very low within, or below, the base of the Jehe Group. Our data also suggest that the Berriasian-Hauterivian (Neocomian) age suggested for the one known Russian locality that has yielded P. mongoliensis (Shestakovskaya Svita at Gorno-Altayaskaya, Avtonomnaya Oblast) may be excessively old. The coarsening-upward clastic sequence at Tebch, Inner Mongolia, China, containing the dinosaur Psittacosaurus mongoliensis, comprises the remains of a fluviolacustrine system deposited in an extensional tectonic setting. The presence of Asteropollis sp. cf. Asteropollis trichotomosulcatus (Singh) Singh, 1983 in conjunction with the absence of tricolpate pollen indicates a Barremian or possibly early Aptian age. The overlying Tebch basalt, dated by the 40Ar/39Ar laser step-heating method, yields a mid-Aptian age of 110 +/- 0.52 Ma. This chronology supports the argument that the Juifotang Formation of the Jehe Group in western Liaoning is Early Cretaceous, with the Jurassic-Cretaceous boundary very low within, or below, the base of the Jehe Group. Our data also suggest that the Berriasian-Hauterivian (Neocomian) age suggested for the one known Russian locality that has yielded P. mongoliensis (Shestakovskaya Svita at Gorno-Altayaskaya, Avtonomnaya Oblast) may be excessively old. The coarsening-upward clastic sequence at Tebch, Inner Mongolia, China, containing the dinosaur Psittacosaurus mongoliensis, comprises the remains of a fluviolacustrine system deposited in an extensional tectonic setting. The presence of Asteropollis sp. cf. Asteropollis trichotomosulcatus (Singh) Singh, 1983 in conjunction with the absence of tricolpate pollen indicates a Barremian or possibly early Aptian age. The overlying Tebch basalt, dated by the 40Ar/39Ar laser step-heating method, yields a mid-Aptian age of 110 +/- 0.52 Ma. This chronology supports the argument that the Juifotang Formation of the Jehe Group in western Liaoning is Early Cretaceous, with the Jurassic-Cretaceous boundary very low within, or below, the base of the Jehe Group. Our data also suggest that the Berriasian-Hauterivian (Neocomian) age suggested for the one known Russian locality that has yielded P. mongoliensis (Shestakovskaya Svita at Gorno-Altayaskaya, Avtonomnaya Oblast) may be excessively old.