从综合地层学的观点论华南上泥盆统和下石炭统年代地层划分

ON THE UPPER DEVONIAN AND LOWER CARBONIFEROUS CHRONOSTRATIGRAPHICAL DIVISION OF SOUTH CHINA FROM THE VIEWPOINT OF INTEGRATED STRATIGRAPHY

运用综合地层学方法讨论了华南上泥盆统和下石炭统年代地层划分。为了便于和国际年代地层标准进行对比，建议把华南岩关阶的底界提高到与国际上泥盆系—石炭系界线相一致的位置，把上泥盆统锡矿山阶与修订后的岩关阶之间的地层归入邵东阶。邵东阶和岩关阶分别相当于欧洲的斯特隆阶和杜内阶。这个方案使阶与地球演化的自然节律相对应。阶的界线和重大地质事件吻合，它不仅是一条生物地层界线，而且有明显的事件地层标志。在邵东阶和岩关阶之间的界线上古群落的分布模式和地层的磁学特征及地球化学特征都发生了显著变化，可能代表一条自然界线。从层序地层学的观点来看，邵东阶大体由１个三级层序组成，岩关阶由３个三级层序组成。上述各种地质事件中，海平面升降似乎起着关键性主导作用，其变化导致了生物群、古群落的分布模式、沉积层序的发育及地层磁学特征和地球化学特征的变化。

n the present paper an attempt is made to discuss the Upper Devonian and Lower Carboniferous chronostratigraphic division of South China from the viewpoint of integrated stratigraphy. In order to make the chronostratigraphic units established in South China to cope with international standard, the lower boundary of the traditional Yanguanian Stage is moved upwards to the DevonianCarboniferous boundary, and the strata between the Xikuangshanian and Yanguanian stages are referred to the Shaodongian Stage. The Shaodongian and Yanguanian stages of South China correspond to the Strunian and Tournaisian stages of Europe respectively. This scheme makes the stages to correspond to the natural rhythms of Earth's evolution and the stage boundaries to coincide with important geological events, which are not only a clear biostratigraphic, but also a distinct event stratigraphical boundary. Remarkable changes in palaeoecologic pattern and sudden variation in magnetic susceptibility and stable isotope of limestones occurred at the DevonianCarboniferous boundary, which may probably denote a natural boundary. From the viewpoint of sequence stratigraphy, the Shaodongian Stage will include only one sequence and the Yanguanian Stage three sequences in general. Among the events mentioned above, the rise and fall of sealevel seem to play a key role. This variation results in the changes of fauna, palaeoecological pattern, depositional sequences, magnetic susceptibility and stable isotope of limestones.