Lithostratigraphy and depositional history of the Late Cenozoic hominid-bearing successions in the Yuanmou Basin, southwest China

Late Cenozoic strata bearing hominids and hominoids are distributed in the Yuanmou Basin, Yunnan, southwest China. Incisors of Homo erectus discovered in these strata in 1965 reportedly show primitive features known in Africa (Hu, Acta geologica sinica 1 (1973, p. 65). However, recent paleomagnetic study has revealed that the age of the hominid correlates to the early Brun hes chron (Hyodo et al., Journal of human evolution (2001), submitted). The lithostratigraphy of the successions that yield many mammalian fossils inc luding those of the hominid, and the record of Equus is re-examined. The su ccessions are divided in ascending order into the Longchuan, Shagou, Gantan g (newly proposed Yangliuchun and Daipojing Members) and Yuanmou (newly pro posed Dainawu and Niujianbao Members) Formations, based on different lithol ogy and sedimentary facies. The newly proposed depositional systems of the formations are in ascending order, alluvial fan, ephemeral braided river, s andy braided river, ephemeral gravelly braided river and alluvial fan syste ms. The change in facies and paleocurrents revealed in the successions sugg est that the basin was initiated as a syncline basin at ca 3.5 Ma and was c ompleted as an asymmetric half graben by active movement of the eastern mar ginal fault in the early Middle Pleistocene. (C) 2001 Elsevier Science Ltd. All rights reserved.