华南沿海第四纪类网纹红土的赋存层位及其年代问题

The Problems of Stratigraphy and Chronology of Like-Vermicular Red Earth Formed in the Quaternary along the Coast of South China

根据地质学、地貌学、沉积学、地球化学和年代学的研究,将华南沿海(南岭以南)不同时代的杂色粘土(暂称"类网纹红土")划分为基岩风化壳型和松散沉积风化壳型两种类型;将第四纪松散沉积系列中的杂色粘土划分为第四纪早期(年代为1.8～1.6MaBP)、中期(年代为1.0～0.8MaBP)和晚期(年代为0.07～0.01MaBP)3个发育期;主要讨论了发育好、厚度大、分布广的第四纪中期杂色粘土与长江流域和西南丘陵区典型网纹红土之间在赋存层位、剖面结构和发育年代等方面的差别和存在问题,提出了需进一步研究杂色粘土—网纹红土的年代和发育规律及其反映的中国南方地质—气候环境演化规律等重要科学问题。

Analyses of geology,geomorphology,sedimentology,geochemistry and geochronology allow us to classify the variegated clays （as one of the vermicular red earth,we may call it the ＂like vermicular red earth,＂） which had formed in different periods along the coast of South China （areas to south of the Nanling Mountains） into two types：the weathering crust of bedrock and the weathering crust of unconsolidated sediments,and identify the variegated clays in the Quaternary unconsolidated sediment sequence with 3 pedogenesis stages：the early stage,which ranges approximately from 1.8 to 1.6 Ma BP,the middle stage,approximately from 1.0 to 0.8 Ma BP,and the late stage,approximately from 0.07 to 0.01 Ma BP.Our present paper primarily focuses on the problems and differences of horizons,profile texture and geochronology between the best developed,thickest and most widely distributed variegated clays with the age of 1.0 to 0.8 Ma BP in the coastal South China and the typical reticulate red clays in the Yangtse River valley and the southwestern hill areas of China.Moreover,we suggest that some important scientific problems,such as the pedogenises laws of variegated clays and reticulate red clays,the development-evolution intensity and laws of the weathering,and their signification to indicate the geological and climatic evolution in southern parts of China,will need further research.