Magnetostratigraphy of the late Cenozoic Laojunmiao anticline in the northern Qilian Mountains and its implications for the northern Tibetan Plateau uplift

摘要: Cenozoic sediments in the foreland basin——Jiuquan Basin west Hexi Corridor recorded tectonic uplift information of Qilian Mountains. High resolution paleomagnetic dating Laojunmiao (LJM) section across central LJM anticline southern Jiuquan reveals ages Getanggou Member, Niugetao Member Shulehe Formation, Yumen Conglomerate, Conglomerate and Gobi Formation at >13―8.3 Ma, 8.3―4.9 3.66―0.93 0.84―0.14 Ma 0.14―0 respectively. Sedimentary evolution study suggests that Mountains should begin to rise gradually since ~8―6.6 accompanied by sedimentary environments changing from lacustrine mudstones-sandstones alluvial conglom-erates. Rapid began ~3.66 followed a series stepwise or intermittent intensive uplifts about <1.8―1.23 0.93―0.84 0.14 which finally resulted present high