title: Late Oligocene-Early Miocene magnetochronology of the mammalian faunas in the Lanzhou Basin-environmental changes in the NE margin of the Tibetan Plateau.
abstract: A large number of terrestrial mammalian fossils were reported in the well-exposed Paleogene and Neogene fluvio-lacustrine strata in Western China. Their accurate ages are crucial to understand the mammalian and environmental evolution associated with the step-wise uplift of the Tibetan Plateau. At present their ages are surprisingly poorly constrained. Here, we present a high-resolution magnetostratigraphic dating of the Late Oligocene-Early Miocene mammal assemblages from a 233-m thick fluvio-lacustrine section in the Lanzhou Basin located at the northeastern margin of the Tibetan Plateau, China. The results suggest that the section spans from the polarity subchron C6Cn.2r to C5En, i.e. ranging from ca 23 to 18 Ma. This magnetochronology provides considerably more robust ages for three associated land mammalian faunal assemblages. Updated ages end the debate on existing ambiguous and distinctly different magnetostratigraphic correlations for those Late Oligocene-Early Miocene assemblages. The new ages now enable precise correlation of these faunas to the European Land Mammal and North American Land Mammal Ages. The faunal assemblages further suggest a mixed setting of woodlands and grasslands associated with a humid environment in the Lanzhou Basin during the Late Oligocene-Early Miocene, in contrast to its modern poor vegetation cover and arid environment.
authors.affiliation: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Ao
authors.affiliation: Paleomagnetic Laboratory 'Fort Hoofddijk', Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, The Netherlands.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Dekkers
authors.affiliation: State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China.
authors.forename: Yongxiang
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China.
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: An
mesh_terms: D000818:Animals; D017753:Ecosystem; D005580:Fossils; D060526:Magnetic Fields; D008322:Mammals / Q000502:physiology*; D018609:Tibet