目前对于板溪群顶界及其与南华冰期的关系待认识还存在很大分歧,主要体现在两个方面:接触关系和年代地层格架。这也是目前我国“南华系”涵义厘定及其层型剖面选择过程中亟待解决的关键问题。实际上板溪期和南华冰期沉积的同位素年代学数据,目前已经很多了,但出现的问题也很多,最主要问题出在对测试对象的鉴别和测试数据的解释上。对于测试对象,这里有两个值得重视的问题:一是对于斑脱岩和薄层凝灰岩或凝灰质岩样品而言,存在大量继承性锆石或源区锆石是不可避免的,因此,在进行样品年龄统计计算时,首要任务就是尽可能剔除继承性锆石的影响。二是凝灰质沉 At present, there are still many differences between the understanding of the top of the Banxi Group and the relationship with the South China Ice Age, which is mainly reflected in two aspects: the contact relationship and the stratigraphic framework of the Chronostratigraphy. This is also the key issue to be solved urgently in the process of determining the meaning of “South China Department” and the selection of its stratified profile in our country. Actually, the isotopic geochronological data of Banxi Period and South China Ice Age deposition have been much, but many problems have appeared. The main problem lies in the identification of test objects and the interpretation of test data. There are two important issues for the test object: First, for the samples of bentonite and thin tuff or tuff, there are a large number of inherited zircons or source rocks that are unavoidable. Therefore, When calculating the sample age, the primary task is to eliminate as much as possible the impact of inherited zircon. Second, tuff Shen