Iridium Anomalies of Late Eocene Age at Massignano (Italy), and ODP Site 689B (Maud Rise, Antarctic)
Iridium Anomalies of Late Eocene Age at Massignano (Italy), and ODP Site 689B (Maud Rise, Antarctic)
复制标题
马西尼亚诺（意大利）和 ODP 站点 689B（南极洲莫德海隆）始新世晚期的铱异常
作者：
A. Montanari;F. Asaro;H. Michel;J. Kennett
这里报告了意大利北部和南极威德尔海的序列中始新世晚期的铱异常。我们分析了来自意大利马西尼亚诺始新世/渐新世边界层型剖面的 270 个泥灰岩样本，时间范围为 35.6 至 34.5 Ma（NP 18 区至 NP 19/20 区）。我们在下部钙质超微化石 NP 19/20 带中发现了一个明显的 Ir 峰值，为 156 ± 19 万亿分之一 (ppt)，对应于有孔虫 P16 带的中下部和磁性 Chron 16n2 的顶部。该 Ir 异常的年龄是 35.7 ± 0.4 Ma，源自同一剖面中发现的数个已测年火山灰
Iridium anomalies of Late Eocene age are here reported in sequences from northern Italy and Weddell Sea, Antarctic. We have analyzed 270 samples of marly limestones from the Eocene/Oligocene boundary stratotype section at Massignano, Italy, ranging from 35.6 to 34.5 Ma (NP 18 Zone to NP 19/20 Zone). We discovered a distinct Ir peak of 156 ± 19 parts per trillion (ppt) in the lower calcareous nannofossil NP 19/20 Zone, corresponding to the mid-lower part of foraminiferal P16 Zone, and the top of magnetic Chron 16n2. The age of this Ir anomaly derived from several dated volcanic ashes found in the same section is 35.7 ± 0.4 Ma