Annotated record of the detailed examination of Mn deposits from DSDP Leg 1 (Holes 4 and 7A)@en

Visual examination of the cores and microscopic examination of smear slides of the wide variety of sediments cored on Leg 1 revealed an equal range of particle origins, modes of transport, and manner of deposition. Brown deep-sea clays characterize the uppermost (Pliocene-Pleistocene) sediments of the Atlantic sites, and red deep-sea clay was cored below Middle Eocene sediments at Site 7. The main mineral constituents are clay minerals and quartz. The color results mainly from iron and manganese minerals. Manganese oxides are present in small nodules in theses red clays. The X radiographs of Site 4 and Site 7 commonly show a distinct granular texture, presumably because of the X-ray opaque limonite and pyrite grains. For Site 4 they also show larger ferruginous and possibly manganiferous nodules, some of which appear to be mineralized pumice fragments. With certain exceptions, the general composition of the brown and red clays cored on Leg 1 (the presence of much kaolinite and quartz, and scarcity of zeolite) suggests a largely terrigenous origin.对第1航次（Leg 1）获取的各类沉积物岩心开展目视岩心检查与涂抹片显微分析后发现，其颗粒成因、搬运方式与沉积模式均呈现出广泛的分布范围。大西洋各钻探站位的最上层（上新世-更新世）沉积物以褐色深海黏土为特征，而7号站位（Site 7）中始新统沉积物下方则钻取到红色深海黏土。其主要矿物成分为黏土矿物与石英，颜色主要由铁矿物与锰矿物赋存所致。这类红色黏土中可见呈细小结核状产出的氧化锰矿物。4号站位（Site 4）与7号站位（Site 7）的X射线影像通常呈现出清晰的粒状结构，推测这是由X射线不透明的褐铁矿与黄铁矿颗粒导致。针对4号站位，其影像还显示出更大的铁质结核及可能含锰的结核，其中部分疑似为矿化浮石碎屑。尽管存在个别例外，第1航次钻取的褐色与红色黏土的整体矿物组成（富含高岭石与石英、且沸石含量稀少）表明其成因主要为陆源成因。