REE-rich sediments in the Central Pacific Basin and their acoustic characteristics

To understand the enrichment mechanism of rare earth elements(REE) in the deep-sea sediment, and the regional stratigraphy of the Central Pacific Basin, Guangzhou Marine Geological Survey carried out shallow stratigraphic profile survey, single channel seismic profile survey and piston core sediment sampling in 2013, based on the method of geophysical exploration in combination with geological sampling.The following five stratigraphic units were identified by means of shallow stratigraphic profile survey and single channel seismic profile survey: ①0~12 m, Quaternary-Upper Oligocene pelagic clay; ②12~58 m, Middle Oligocene-Eocene(Late Cretaceous?) chert layer and limestone; ③58~127 m, Late Cretaceous nannofossil ooze, chalk; ④127~144 m, limestone with chert; e, and basalt.The results of lithology and element geochemical analysis indicate that the enrichment of REE in deep-sea sediments is mainly due to the contribution of biogenic apatite and volcanic hydrothermal components, while terrigenous components are not conducive to the enrichment of REE.The REE-rich deposits in the study area are mainly in pelagic transparent clay layers on the top, while the high impedance chert layers in the lower part since Oligocene can be considered as the bottom boundary of the REE-rich deposits.The results show that the targeted sedimentary layer can be quickly identified in the REE-rich sediment survey, under the guidance of shallow stratigraphic profile survey, which can provide technical support for the exploration of deep-sea potential REE resources.