广东连州长兴期含煤地层

THE CHANGHSINGIAN COAL-BEARING FORMATION OF LIANZHOU,GUANGDONG

九陂组(亚田煤组)是粤北和湘南晚二叠世重要的含煤地层,其下伏"梅田灰岩"的涵义和化石Galloway-inella meitienensis的层位问题曾长期未得澄清。通过对梅田组剖面的详细工作,建立了下部的Gallowayinella组合和上部的Nanlingella jiaozishanica-Sphaerulina subrotunda组合。位于麻田组与梅田组之间的九陂组(亚田煤组)上界还达不到长兴阶的顶部,其下限则高于Gallowayinella组合,但不低于Palaeofusulina sinensis亚带的中上部。这样,九陂组(亚田煤组)的时代应定格在P.sinensis亚带的上部,但不包括该亚带的顶部。九陂组不能称作是华南二叠纪层位最高的含煤地层。同时对类Gallowayinella和植物"Ullmannia cf.bronnii"的时代分布等问题作了简要的讨论。

The Jiupi Formation （the Yatian Coal-bearing Formation） is an important coal-bearing sequence in Guangdong Province, but the definition of the underlying ＂Meitien Limestone＂ and the stratigraphic position of Gallowayinella meitienensis Chen have not been clarified for a long time. Through a detailed survey of the Meitien Formation, two fusulinid assemblages have been recognized, which are the Lower Gallowayinella Assemblage and the Upper Nanlingella jiaozishanica-Sphaerulina subrotunda Assemblage. The Lower Assemblage can be correlated with the Palaeofusulina minima-Nankinella guizhouensis subzone of the Palaeofusulina zone, and the Upper one may be correlated with the middle-lower part of the Palaeofusulina sinensis subzone of western Guizhou. As being positioned between the Marian Formation and the Metian Formation, the upper boundary of the Jiupi Formation should be lower than the top of the Changhsingian, and its lower limit should be higher than that of the Gallowayenella Assemblage, but not be lower than the middle-lower part of the Palaeofusulina sinensis subzone. Thus, the Jiupi Formation re- presents the upper Palaeofusulina sinensis subzone, but does not include the uppermost of this subzone. So, the Jiupi Formationshould not be regarded as the highest Permian coal-bearing strata in South China. The present paper also deals with the character and geological distribution of ＂Ullmannia cf. bronnii＂, which was regarded as aChanghsingian index plant fossil in South China. Recent study of this plant fossil shows that ＂Ullmannia el. bronnif＂ from South China has no affinities with the European genus Ullmannia, and a new taxon Szecladia multinervia has been created for the specimens from South China. Besides, the new facts show that ＂Ullmannia cf. bronnii＂ was found together with the braehiopod Squamularia grandis Chao, which is regarded as a characteristic form of late Wuehiapingian in western Guizhou and eastern Yunnan. Moreover, ＂Ullmannia cf. bronnii＂ was also found in the Lower Member of the Xuanwei Formation together with ＂Ullmannia frumentaria＂, which was regarded as an index fossil of the Capitanian coal-bearing strata in South China. Obviously, ＂Ullmannia cf. bronnii＂ can not be regarded as an index fossil of Changhsingian age, although it is commonly described as such in the geological literature.