中文摘要：

介绍了中国南方红土的年代学发展状况,指出前人的红土研究主要集中于松散沉积物型红土剖面,在很多情况下利用常规的定年技术难以直接获取剖面的绝对年代信息。利用风化壳中次生矿物的析出时间作为风化剖面的形成时间无疑是最合理的定年方法,国内已有的风化年代学进展来自以隐钾锰矿为代表的锰钡矿族锰氧化物的~40Ar/~39Ar法定年。风化剖面定年的主要顾虑之一是难以获取纯净的、完全不受地下杂质影响的有意义的定年样,因此,本文重点研究了以隐钾锰矿为代表的锰钡矿族锰氧化物的矿物识别和样品制备。粉晶X-衍射、扫描电镜和能谱分析表明：通过严格的矿物鉴定可以获取合适的矿物单晶,如果加上合理的~40Ar/~39Ar激光阶段性加热分析可以研究含有锰钡矿族锰氧化物的风化壳型红土剖面。

英文摘要：

The development of geochronology of the red earth in South China is introduced in this paper. It is pointed out that previous geochronological investigations on South China’s red earth have primarily focused on the weathering profiles of red earth developed on quaternary sediments. However, in many cases, absolute geochronological information is unobtainable when conventional techniques are used, that constrains the research on red earth of South China. Undoubtedly, the most appropriate approach to the timing of weathering process would be to determine the precipitation age of supergene minerals from the weathered profiles. Recent progress in the geochronology of weathering process in China has been made in the application of 40Ar/39Ar dating of hollandite-group manganese oxides, which often precipitate through weathering reactions. One of the major problems on the geochronology of weathering profiles is the difficulty in obtaining pure fractions of the supergene phase without hypogene contaminants. Consequently, here the authors pay attention to the identification and sample preparation of cryptomelane representative of hollandite-group manganese oxides. The analyses of XRD, SEM and EDX show that strict identification of supergene minerals can pick the single-crystal for the 40Ar/39Ar method of laser incremental heating, that allows to study weathering profiles of red earth where hollandite-group minerals occur as minor phases.