Composition and origin of sediments at DSDP Site 54-424

The sediments recovered on Deep Sea Drilling Project Leg 54 appear to be mixtures of the normal pelagic sediments of the area and hydrothermally produced manganese and iron phases. The latter are mineralogically and chemically very similar to phases recovered from surficial sampling of the mounds. The hydrothermal nontronite which is approximately 15 meters thick in the three holes is essentially free of carbonate or detrital contaminants. The basal sediments are similar to the carbonate oozes presently being deposited in the region, but are enriched in Mn and Fe. This enrichment appears to be the result of hydrothermal deposition that took place at or near the spreading center and may not be associated with the mounds formation. […]深海钻探计划（Deep Sea Drilling Project）第54航次采集的沉积物，似乎为该区域常规远洋沉积物（pelagic sediments）与热液成因锰铁相（hydrothermally produced manganese and iron phases）的混合物。后者在矿物学与地球化学特征上，与对该类丘体开展表层取样（surficial sampling）所获得的物相高度相似。在3个钻孔中厚度约15米的热液成因绿脱石（hydrothermal nontronite），基本不含碳酸盐或陆源碎屑污染物。基底沉积物与该区域当前沉积的碳酸盐软泥（carbonate oozes）特征相近，但锰、铁元素含量显著富集。这种富集现象应为形成于扩张中心（spreading center）之上或其邻近区域的热液沉积作用所致，或与该类丘体的形成并无关联。[…]