Planktonic foraminiferal stratigraphy of sediments from ODP Leg 173 sites@en

Planktonic foraminifers recovered from five sites drilled off western Portugal during Ocean Drilling Program Leg 173 are documented. Hole 1065A yielded planktonic foraminifers from Miocene sediments in Sections 173-1065A-1R-1 through 6R-2. Hole 1067A penetrated middle Eocene sediments containing planktonic foraminifers in Section 173-1067A-1R-1 through Lower Eocene planktonic foraminiferal horizons to Section 12R-CC. Hole 1068A yielded planktonic foraminiferal assemblages from middle Eocene sediments at Section 173-1068A-1R-1 to Maastrichtian sediments at Section 173-1068A-15R-3, whereas Hole 1069A contained middle Eocene taxa in Section 173-1069A-1R-1 through Campanian/Maastrichtian forms in Section 173-1069A-15R-2. All of the planktonic foraminifers recovered from these sites are of poor to moderately good preservation and are variable in abundance. Hole 1070A yielded only six planktonic foraminifers, with the assemblages being dominated by benthic foraminifers and fish teeth. The co-occurrence of other microfossil groups, including benthic foraminifers, are only briefly discussed here. The lower Miocene biosiliceous facies recorded in Hole 1065A is considered to be coeval with a similar facies found in onshore sections farther to the east, in southern Spain.本研究对大洋钻探计划（Ocean Drilling Program）第173航次在葡萄牙西部海域钻取的5个站位所获浮游有孔虫（planktonic foraminifers）进行了系统记述。1065A号钻井孔在173-1065A-1R-1至6R-2岩芯段的中新世（Miocene）沉积物中产出浮游有孔虫。1067A号钻井孔钻穿了173-1067A-1R-1岩芯段中含浮游有孔虫的中始新世（middle Eocene）沉积物，直至12R-CC岩芯段的下始新世（Lower Eocene）浮游有孔虫地层位。1068A号钻井孔的沉积物层位覆盖从173-1068A-1R-1岩芯段的中始新统沉积物，至173-1068A-15R-3岩芯段的马斯特里赫特阶（Maastrichtian）沉积物，其中包含浮游有孔虫生物组合；而1069A号钻井孔的173-1069A-1R-1至173-1069A-15R-2岩芯段中，分别产出中始新世有孔虫分类群与坎潘阶（Campanian）/马斯特里赫特阶化石类型。本次从各站位获取的所有浮游有孔虫，其保存状态多为较差至中等良好，丰度亦存在较大波动。1070A号钻井孔仅产出6枚浮游有孔虫，其生物组合以底栖有孔虫（benthic foraminifers）与鱼齿为主。本次仅简要讨论了包括底栖有孔虫在内的其他微古生物类群的伴生产出情况。1065A号钻井孔所记录的下中新统生物硅质岩相（biosiliceous facies），被认为与西班牙南部境内更偏东的陆上剖面中发现的同类岩相形成时代一致。