4. The Paleomagnetism and Magnetic Stratigraphy of the Late Cenozoic Sediments of the Yushe Basin, Shanxi Province, China

Twenty-four sections in the Yuncu subbasin of the Yushe Basin complex were sampled for magnetostratigraphy. A clear pattern of resolved magnetozones indicates the distinctive pattern of Late Miocene Chron C3An for the oldest part of the sequence, the Mahui Formation. The Gaozhuang Formation is dominantly reversely magnetized and correlated with the Gilbert Chron. The superposed Mazegou Formation represents Gauss Chron, but truncated magnetozones indicate a basal hiatus of about half a million years. These two formations are therefore Pliocene in age. The overlying reversely magnetized Haiyan Formation is correlated with Chron C2r, the early reversed subchron of the Matuyama, Early Pleistocene in age. Four sections in the Tancun subbasin record late Chron C3An and C3r (the latter being early Gilbert Chron). Deposition in both subbasins, near the trunk of the Zhuozhang River, began in the Late Miocene, antedating the commencement of sedimentation in the Zhangcun subbasin. Age control, initially provided by vertebrate fossils, is refined by the magnetostratigraphy, which provides precision for dating the Yushe succession of fossiliferous localities.