The Tunggurian Stage of the Continental Miocene in China

The Tunggurian Age was nominated in 1984, and the Second National Commission on Stratigraphy of China formally suggested establishing the corresponding chronostratigraphic unit, the Tunggurian Stage, based on the Tunggurian Age in 1999. The name of this stage comes from a lithostratigraphic unit, the Tunggur Formation, and the stratotype section is located at the Tunggur tableland, 15 km southeast of Saihan Gobi Township, Sonid Left Banner, Inner Mongolia. The Tunggurian Age is correlated to the Astaracian of the European land mammal ages, and they share the same definition of the lower boundary at the base of the paleomagnetic Chron C5Bn.1r with an age of 15.0 Ma. In the Tairum Nor section on the southeastern edge of the Tunggur tableland, this boundary is situated within the successive deposits of reddish-brown massive mudstone of the lower part of the Tunggur Formation, with a distance of 7.6 m from the base of the grayish-white sandstones in the middle part of the section. The Tunggurian is approximately correlated to the upper part of the marine Langhian and the marine Serravallian in the International Stratigraphical Chart. The Tunggurian Stage includes two Neogene mammal faunal units, i.e. NMU 6 （MN 6） and NMU 7 （MN 7/8）. The Tairnm Nor fauna from the Talrnm Nor section corresponds to NMU 6, and the Tunggur fauna （senso stricto） from the localities on the northwestern edge of the Tunggur tableland, such as Platybelodon Quarry, Wolf Camp and Moergen, corresponds to NMU 7. Among the Middle Miocene mammalian faunas in China, the Laogou fauna from the Linxia Basin, Gansu, the Quantougou fauna from the Lanzhou Basin, Gansu, the Halamagai fauna from the northern Junggar Basin, Xinjiang, and the Dingjiaergou fauna from Tongxin, Ningxia correspond to NMU 6.

A comprehensive construction of the domain ontology for stratigraphy

Stratigraphic knowledge,the cornerstone of geoscience,needs to be represented by the Knowledge Graph based upon ontology,in order to apply the state-of-the-art big-data techniques.This study aims to comprehensively construct the ontologies for the stratigraphic domain.This has been achieved by a federated,crowd intelligence-based collaboration among domain experts of major stratigraphic subdisciplines.The initial step is to enumerate key terms from authoritative references and incorporate them into the Geoscience Professional Knowledge Graphs(GPKGs)of Deep-time Digital Earth Project.During this process,semantic heterogeneities were meticulously addressed by professional judgement aided by an automatic detection of Homonyms at the GPKGs platform.Afterwards,these terms were further differentiated as either classes or properties and arranged in a hierarchical framework in a top-down process.Consequently,seven ontologies are constructed for major stratigraphic branches,i.e.,Lithostratigraphy,Biostratigraphy,Chronostratigraphy,Chemostratigraphy,Magnetostratigraphy,Cyclostratigraphy and Sequence Stratigraphy.The ontology of Biostratigraphy,among them,is elaborated here,as no biostratigraphic ontology has been attempted before to our knowledge.The constructed biostratigraphic ontology comprises following major root classes:Fossil,Biostratigraphic unit,Biostratigraphic horizon.Altogether,they contribute to the eventual dating and correlating of strata in another root class:Biostratigraphic correlation.In summary,the achievements of this study are probably heretofore the most comprehensive ontologies for the stratigraphic domain.Moreover,a proto model of semantic search engine was conceived to discuss potential application of our work for better querying stratigraphic references,utilizing the semantic liaison of the classes in the constructed ontologies.