The anisotropy of magnetic susceptibility of Core NS97-13 sediments from the Nansha Islands sea area in the southern South China Sea

The anisotropy of magnetic susceptibility (AMS) of Core NS97-13 sediments from the Nansha Islands sea area in the southern South China Sea was analyzed combining with ¹⁴C dating, which afforded the magnetic susceptibility ellipsoid of geometry shapes, and paleocurrent directions and depositional forms of sediments were rebuilded in the study area. Results show that (1) the predominant direction of staved ellipsoid (E>1)is always located above the L-F straight line, whose nip angle (β) is 0°<β≤33.14°, whilst the predominant direction of elongated ellipsoid (E<1) is located below the L-F straight line, whose nip angle (a) is 33.14° <α<56.86°. These denote that the direction of hydrodynamic action is different when the magnetic granules deposit in the process of sedimentation. (2) The AMS parameter, (L-P, F-P) are demonstrated that the core sediments experience of reworked, redeposited and undisturbed three forms,and the former two are adulterated in the undisturbed sediment layers, resulting in the intermingled layers. (3) The axial distributions of the maximum susceptibility and the middle susceptibility are mainly NS and NE-SW, explaining that the paleocurrent direction has been mostly NS and NE-SW since about 62ka BP. The total magnetic susceptibility recorded six cold events, namely, the Heinrich layers (H1-H6),showing that there are six cold events in the Nansha Islands sea area.