STUDIES ON MAGNETOSTRATIGRAPHY OF CORE YRD-1101 SEDIMENTS ON THE NORTH SHORE OF MODERN YELLOW RIVER DELTA

Studies of magnetostratigraphy and rock magnetism have been conducted for the samples from borehole YRD-1101that is 200.30 m long and located on the north shore of Modern Yellow River Delta, south coast of the Bohai Sea. Rock magnetic studies indicate that the main magnetic mineral in the sediments is detrital magnetite, with subordinate iron sulfide and hematite. The Brunhes/Matuyama boundary was found at the core depth of 123.33 m, and one incomplete normal polarity zone corresponding to Olduvi Subchron in 191.78-200.30 m. The basal age of the borehole is estimated at about 1.885 Ma by extrapolation of the sedimentation rate in the Matuyama Chron. Our results provide a reliable chronological framework for the borehole, facilitating the stratigraphic division of the Quaternary strata in the Modern Yellow River Delta.