Minerals and geochemistry of DSDP Hole 81-552A

The acid insoluble coarse fractions of the glacial-interglacial sequence of Hole 552A in the NE Atlantic are made up of varying amounts of terrigenous detritus, biogenic silica, and pyroclastic material, principally volcanic glass. Volcanic ash content varies significantly over the entire interval, and the three North Atlantic ash horizons of Ruddiman and Glover (1972) can be recognized satisfactorily. The terrigenous detritus is of mixed metamorphic-basaltic type and probably originated on the Greenland landmass东北大西洋552A钻孔（Hole 552A）的冰期-间冰期序列（glacial-interglacial sequence）中，其酸不溶粗组分（acid insoluble coarse fractions）由不同比例的陆源碎屑（terrigenous detritus）、生物硅（biogenic silica）以及以火山玻璃（volcanic glass）为主要组分的火山碎屑物质（pyroclastic material）构成。该序列全层段的火山灰含量变化显著，可可靠识别出鲁迪曼与格洛弗（Ruddiman and Glover，1972）提出的三个北大西洋火山灰层位。上述陆源碎屑属于混合变质-玄武岩型，其物质来源大概率源自格陵兰陆块。