西太平洋海域底流演化及其对深海富稀土沉积发育的控制

深海富稀土沉积作为一种备受关注的新型深海矿产资源，资源潜力巨大，是陆地稀土资源的重要战略接替资源。西太平洋是全球富稀土沉积最为发育、稀土元素含量最高的海区之一，据推测底流演化是控制该区富稀土沉积发育的关键因素，但缺乏直接的古海洋学证据支持，其控制机制还存在争议。因此，本项目拟选择西太平洋海域2个站位高质量柱状深海沉积物为研究对象，使用古地磁测年法和放射性10Be测年法相结合的测年方案，精确建立研究区高分辨率地层年代格架，进而利用生物磷灰石Nd同位素等指标，恢复研究区地质历史时期底流演化过程。在此基础上，开展广泛的对比研究，重建富稀土沉积形成时的底流活动背景，重点分析氧化环境变化、沉积间断发育和底流强度演化与富稀土沉积发育的成因联系，从而探讨底流演化控制富稀土沉积发育的作用机制。本研究可为解决“深海富稀土沉积成矿机制”这一重大科学问题做出贡献，为深海稀土的资源勘探和评价提供理论依据。

The REY-rich deep-sea sediment, as one of the new deep-sea mineral resources, is widely concerned and has great resource potentialities. It is an important substitute strategic resource to the terrestrial REE resources. There is a wide distribution of REY-rich sediments in the Western Pacific, with the highest concentrations of REY. The evolution of bottom currents is considered as a key factor controlling the formation of REY-rich sediments from the Western Pacific, however, lacks direct paleoceanographic evidences. The controlling mechanism also remains controversial. Thus, this proposal plans to select two deep-sea sediment cores collected from the Western Pacific as the research objects. In combination of the radionuclide 10Be absolute age data and the magnetic age data, the age models of the cores will be established. Nd isotopes of bioapatite fossils and other tracers will be used to reconstruct the evolution process of bottom currents in the study area. On this basis, extensive comparative studies will be carried out to reconstruct the activities of bottom currents at the time REY-rich sediments were deposited. The genetic links between the formation of REY-rich sediments and the controlling factors of oxidation environment changes, the discontinuous in sediments and the intensity of bottom currents will be analyzed. The mechanism of bottom current evolution effects on the formation of REY-rich sediments will be further discussed. Therefore, this proposal will contribute to solving the key scientific issue of "metallogenic mechanism of REY-rich deep-sea sediments", and provide theoretical support for the resource exploration and evaluation of REY-rich deep-sea sediments.