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用铷—锶等时线法测定沉积岩的年龄,许多研究者已做了大量工作,取得了很大成绩。但也还存在不少问题,值得我们进一步讨论。我就某些问题谈一点自己的看法。 一、从理论上讲,用铷—锶全岩等时线法可以测定沉积来源物质的年龄,沉积时间,成岩以及变质作用的时间。沉积岩中通常含有大量他生或碎屑矿物。细粒的碎屑沉积岩,如粉砂岩,页岩以及粘土类岩石,它们的Rb_(87)/Sr_(86)和Sr_(87)/Sr_(86)比值可以构成等时线。
Using the rubidium-strontium isotope method to determine the ages of sedimentary rocks, many researchers have done a great deal of work and achieved great success. However, there are still many problems that deserve our further discussion. I talk about some of my own views. First, in theory, the isotope method of rubidium-strontium whole rock can determine the age, sedimentary time, diagenesis, and metamorphism of sedimentary materials. Sedimentary rocks usually contain a large amount of other raw or detrital minerals. Fine-grained clastic sedimentary rocks, such as siltstone, shale and clay-type rocks, can have isochronal Rb 87 / Sr 86 and Sr 87 / Sr 86 ratios.