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用放射化学中子活化法测定了意大利古比奥地区博塔乔内峡(Bottaccine Gorge)到孔泰萨谷剖面中的Ir、Pd、Pt和Au。页岩和灰岩样品是从白垩/第三系(K/T)界线上面2.85m到界线下面219m的范围内采集的。金属的富集是通过将界线页岩区与剖面下部(背景)进行对比而求出的。与背景相比,界线页岩中的Ir富集了63倍,而其他金属的富集不到2.2倍。Ir的富集不限于界线页岩,而大致扩展到界线上下2m的范围内。除了在K/T界线员岩中Ir发生大的富集外,在这个Ir富集区内还有4个明显的Ir最大值。在地层上,Ir的最大值与爆破型火山作用所特有的冲击矿物丰度的最大值相吻合。灰岩的贵金属含量低于页岩,这大都可以通过其粘土矿物较少来解释。如果用已发表的沉积速率进行计算,那么4m富Ir剖面所代表的时间至少是3×10~5a。在这个时期内,要保持很高的Ir通量,并且能解释K/T界线附近的Ir分布,那么强烈的火山活动可能是比地外物质的冲击更合适的原因。
Radiochemical neutron activation was used to determine the contents of Ir, Pd, Pt and Au from the Bottaccine Gorge to the Contella Valley profile in the Gubbio region of Italy. Shale and limestone samples were collected from 2.85 m above the K / T boundary to 219 m below the boundary. Metal enrichment is determined by comparing the boundary shale area with the lower part of the profile (background). Compared with the background, Ir in the boundary shale enriched 63 times, while other metals less than 2.2 times. The enrichment of Ir is not limited to the boundary shale, but generally extends up to 2m above and below the boundary. In addition to the large enrichment of Ir in K / T liners, there are four distinct maximums of Ir within this Ir enrichment zone. On the strata, the maximum value of Ir coincides with the maximum of the impact mineral abundance unique to the blasting volcanism. Limestone has a lower precious metal content than shale, which is mostly explained by its lower clay mineral content. If calculated with the published deposition rate, the 4m Ir-rich section represents a time of at least 3x10-5a. During this period, to maintain a high Ir flux and account for the Ir distribution near the K / T boundary, intense volcanic activity may be the reason more appropriate than the extraterrestrial impact.