中印度洋洋盆GC11岩心富稀土深海沉积的元素地球化学特征

The geochemical characteristics of rare earth elements rich deep sea deposit of Core GC11 in central Indian Ocean Basin

对中印度洋洋盆的沉积GC11岩心开展了主量元素、微量元素和稀土元素分析研究,根据主微量元素相关性特征、稀土元素富集程度以及澳大利亚后太古代平均页岩归一化模式特征,初步探讨了GC11岩心的沉积地球化学特征,以及影响稀土元素富集的可能因素。研究表明,GC11岩心稀土元素总量在400.64×10^?6~742.74×10^?6,平均值为658.41×10^?6,略低于邻近海域的GC02岩心,与沃顿海盆DSDP213岩心中含沸石型深海粘土层位中的稀土元素含量相当。δCe负异常明显,(La/Yb)N为0.42,显示重稀土相对富集的特点。稀土元素与P2O5呈显著正相关性,CaO/P2O5的平均值为2.3,表明生物钙磷灰石可能是稀土元素的主要载体矿物,而铁锰水合物可能对富集稀土元素有一定的促进作用,但影响不大;GC11岩心中δCe负异常程度远低于GC02岩心,略低于DSDP213岩心,中稀土富集特征与GC02和DSDP213岩心基本一致。不同程度陆源物质的混入可能是导致以上不同岩心中稀土元素富集程度和分馏特征的主要原因。

Measurement of major elements,trace elements and rare earth elements(REY)for sediment Core GC11 collected in the central Indian Ocean Basin were performed.Based on the analysis of interelemental correlation,REY enrichment and post-Archean Australian Shale(PAAS)normalization style,the factors impacting the REY enrichment are discussed.The study suggests that:the total amount of REY varies from 400.64×10^?6 to 742.74×10^?6,with an average of 658.41×10^?6,which is slightly lower than that of Core GC02,however,is equivalent to that of the zeolite-bearing rich deep-sea deposit in the Core DSDP213.The sediment exhibits distinct negative abnormalδCe and lower(La/Yb)N为0.42,with obvious positive correlation between REY and P2O5.The average value of CaO/P2O5 ratio is 2.3,demonstrating that the bio-apatite may be the main host mineral of REY.Although there is positive correlation between REY and Fe and Mn,hydroxyl hydrate of Fe and Mn have low impact to the enrichment of REY for the distinct negative abnormalδCe.The mixture with the terregeneous materials maybe the main cause inducing the differences of REY enrichment degree,δCe and PAAS normalization style.