Magnetostratigraphy Of Paleogene In Erlian Basin

Since the 19^th century, although Cenozoic stratigraphy have developed quickly both at home and abroad, the field of Paleogene magnetostratigraphy have made less progress in China. After many years' study, biostratigraphy of Erlian Basin is important for the evolution of mammals in China and Asia, and lays foundation for the comparison of mammals between continents and for the Asian Land Mammalian Age. Until now, more and more researches indicate that the early studies are in contradiction with each other. Beyond enriching the subject, this research, which establishes the regional timescale of Erlian Basin during Paleogene period, will have important significance for evolution pattern of regional mammal and environment and for comparison of mammals between continents.This thesis reports the paleomagnetic results of Nuhetingboerhe Section and Huheboerhe Section, both of which are new measured and richly fossiliferous sections in Erlian Basin. The paleomagnetism data indicate that the composite Paleogene section from Nuhetingboerhe-Huheboerhe area, Erlian Basin, records 5 normal polarity zones and 6 reversed polarity zones. These polarities can well be correlated to the chron C21r-C26r of GPTS 2004 (Lourens et al., 2004), though some zones are not intact. Nomogen Fm. mainly consists of late Paleocene deposits, except some earliest Eocene strata and a little middle Paleocene material, coarsely from 54.8 to 59.2Ma B.P.. Arshanto Fm. lasts a longer time, spanning from early Eocene to middle Eocene, in the range of 48.2～54.1Ma B.P.. Irdin Manha Fm. is entirely constrained within middle Eocene, coarsely within 47～48Ma B.P.. The age of the fossiliferous bed found fossils of Lambdopsalis, Prionessus and Palaeostylops is about 58.4Ma B.P.; Another fossiliferous bed mainly containing Gomphos is about 55.7 Ma B. P..Finally, the significance of the new age of Paleogene is discussed. Meanwhile, the Paleocene-Eocene boundary, Paleocene-Eocene Thermal Maximum(PETM) and other probable factors that have influenced the succession of mammals are also mentioned.