Stratigraphy and environmental evolution of late Quaternary in Baotou area,Inner Mongolia,China

According to the systematic analysis of lithology,chronology and sedimentary facies of Baotou BT1-1 hole section,it is showed that the section presents the strata since 130 ka B. P.,which can be divided into 3sections. Holocene series( Qh) is a set of fluvial facies strata,that formed at 11. 9ka B. P.. Upper Pleistocene series( Qp32),is a set of alternating deposition between rivers and lakes,that formed at 118. 5ka B. P.. The top of the Middle Pleistocene series( Qp22) is a set of Lacustrine sediments,that formed at 130. 6ka B. P.. The sedimentary environment of Baotou during the late Quaternary had gone through deep lakes during the last stage of Middle Pleistocene- alternating environment between rivers and lakes during Late Pleistocene-- river environment mainly during Holocene. The Glauber's salt layer formed at the climate of cold and arid between 128. 2- 126. 4ka B. P. is a marker bed of the lacustrine sediments in this area.