西太平洋深海盆地孔隙水稀土元素特征及其对沉积物稀土富集机制初探

深海富稀土沉积物已成为国际重要的战略储备资源，但关于其富集机制问题目前仍未得到根本性解决。前期的研究主要集中在沉积物本身，针对沉积物孔隙水的研究工作较为缺乏，而孔隙水作为沉积物稀土元素富集过程的重要环节，其特征分析对揭示REE具体的富集过程和机制具有重要指示意义。课题组前期已初步探讨了深海沉积物浅表层孔隙水的REE特征，本项目拟将研究拓展至更富稀土的深层沉积物，把孔隙水作为主要研究对象，对西太平洋海盆高分辨率系统采集的孔隙水样品开展REE和微量元素的精确测定，并与底层海水和沉积物结果进行系统对比，揭示研究区沉积物早期成岩过程中稀土元素在海水-孔隙水-沉积物三相中的分异、迁移和富集过程。与此同时，分析沉积物的物理性质和矿物特征，确定氧化还原条件，量化REE的扩散和埋藏通量，并与其他海域进行对比，有望从机理上解决REE的富集机制问题，对我国深海稀土资源的调查和研究工作具有重要科学意义。

As a new strategic resources, REE-rich sediments in deep-sea basin has shown important economic significance. The enrichment mechanism of REE-rich sediments remains highly controversial issues and poorly understood. Present research works mainly focus on sediments, however, there are still few investigations for porewater. As the important link of REE enrichment process, porewater geochemistry have great significance in revealing the detailed enrichment process and mechanism of REE. Previous work of our research group has shown the REE geochemistry of porewater in surface and shallow sediments in basin. This proposal aims at deeper sediments and high resolution geochemical characteristics precise analysis of REE and trace elements in porewater samples. We will show the fractionation, migration and enrichment rules of REE in seawater-porewater-sediment in early diagenesis stage compared with the bottom seawater and sediments. Meanwhile, the physical and mineral features, redox condition and flux of diffusion and sedimentation will be discussed to reveal the enrichment mechanism of REE-rich sediment theoretically by contrast with the other area. This result will provide important scientific significance for deep sea REE resources investigation in China.