太平洋中部富REY深海粘土的地球化学特征及REY富集机制

Enrichment Mechanism of REY and Geochemical Characteristics of REY-Rich Pelagic Clay from the Central Pacific

深海沉积物中的稀土资源是一种新发现的、潜在的海底稀土资源.对太平洋中部重力活塞取样获得的90个深海粘土样品的矿物组分、常量和稀土化学分析结果进行了系统分析,并与中北太平洋以及西北太平洋南鸟岛附近海域深海沉积物稀土元素地球化学特征进行了对比.研究结果表明:太平洋中部深海粘土以富含沸石、富P及富REY为特征,其碎屑矿物中含有较多的鱼牙骨,其P2O5与CaO之间、P2O5、CaO与∑REY之间呈良好的正相关关系;其稀土分布模式表现为明显的Ce负异常、一定程度的重稀土元素富集和Y正异常.太平洋中部深海粘土REY富集的主要原因是深海粘土中含有过量的磷酸盐组分,推测过量的磷酸盐组分是由于深海粘土中鱼牙骨碎屑的加入引起的.在北太平洋海域,未受到热液活动影响的条件下,富REY的深海沉积物的稀土元素富集机制具有统一性和普遍性,可以归纳为深海沉积物中高REY磷酸盐的混入作用.

REE resources from deep-sea sediments is a kind of newly discovered and latent REE resources deposited on the ocean floor.Mineral component,major element and rare earth element analysis of 90 pelagic clay samples by piston core from the cen-tral Pacific have been conducted and compared with the geochemical chemistry of pelagic sediments from the central North Pacifc and Minami-Torishima area in the western North Pacific in this study.The results show that the pelagic clay from the central Pacific is rich in phillipsite,P,and REY,and significant fish teeth debris are contained in detrital component of pelagic clay;CaO and P2 O5 ,CaO,P2 O5 and ∑REY are positively correlated,and characterized by clear Ce negative anomaly and cer-tain HREE enrichment and Y positive anomaly in REE distribution.The REY enrichment of pelagic clay from the central Pacif-ic is mainly caused by excess phosphate component which may have resulted from the fish teeth debris mixed in the pelagic clay. The REY enrichment mechanism of REY-rich pelagic sediments in the North Pacific with no hydrothermal effect shows uni-formity and universality,which can be attributed to the admixture of high-REY phosphate in the pelagic clay.