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自从1980年,美国Alvarez小组首先报道白垩纪和第三纪之间的界线粘土层中有异常高的铱含量以来,各国科学家在寻找地质界线的铱异常方面,已取得了大量成果。迄今,不仅已发现全世界五十余处的白垩系一第三系界线有铱异常外,而且还发现在前寒武系—寒武系、泥盆系—石炭系、上泥盆系的弗拉斯阶—法门阶、二叠系—三叠系、中侏罗系—上侏罗系、始新世—渐新世等界线层,也有着程度不同的铱富集。铱异常的研究加深了对古生物进化、地质历史的演化、地层界线的划分、以及天、地生相关系等许多重大地学问题的认识。
Since 1980, when the Alvarez group in the United States first reported that there was an unusually high content of iridium in the boundary clay layer between the Cretaceous and the Tertiary, a great deal of achievements have been made by scientists from all over the world in finding the iridium anomalies at the geological boundary. So far, it has been found that there are not only Iridium anomalies in more than 50 Cretaceous-Tertiary boundaries in the world, but also in the Precambrian-Cambrian, Devonian-Carboniferous, Upper Devonian The Ralstonian-Famenian, Permian-Triassic, Middle Jurassic-Upper Jurassic, Eocene-Oligocene boundary strata also have different levels of iridium enrichment. Iridium anomalies deepen the understanding of paleontology evolution, evolution of geological history, division of stratigraphic boundaries, as well as many important geological problems such as the relationship between heaven and earth and earth.