NEW ADVANCES IN THE ORDOVICIAN GRAP-TOLITE-BEARING STRATA FROM THE HULE AREA IN NINGGUO COUNTY,SOUTHERN ANHUI
安徽省宁国县胡乐地区含笔石地层研究新进展

The Ordovician System is well developed in the Hule area of Ninggou, southern Anhui. Prof. Hsu studied the Ordovican of this area in detail and established two famous formations, the Ninkuo Shale and the Hule Shale, fifty years ago. Recently, the present authors studied the Ordovician System in the Hule area. Some advances in the graptolite-bearing strata have been made. In the past, the Xinchangian (Tremadocian) graptoJites have not been discoveredin southern Anhui. The authors collected a considerable amount of Xinchangian graptolites from the top part of the Xiyangshan Formation, formerly assigned to the Upper Cambrian, and established two graptolite zones, the Staurograptus zone and the Anisograptus-Clonograptus zone. These two zones may be correlated with the Staurograptus-Anisograptus zone (X 1) and Adelograptus-Clonograptus zore (X2) of the Xinchangian Stage respectively.There were two graptolite zones i. e. Glossograptus hincksii zone and Dicranograptus nicholsoni diapason zone, established in the Hulo Formation, belonging to the Middle Ordovician in the Hule area. Recently, Zhang, Li et al. (1982) supplemented one graptolite zone, Dicranograptus sinensis-Climacog-raptus bicornis zone in the Hule Formation. Thus, the Hule Formation may be divided into three graptolite zones as follows:3. Dicranograptus sinensis-Climacograptus bicornis zone (Hu3)2. Dicranograptus nicholsoni diapason zone (Hu2)1. Glossograptus hincksii zone (Hu1)In studying, the present authors discovered some specimens of Nemagraptus at Jinxiqiao and more specimens of Nemagraptus, such as N. gracilis, N. surcularis, at Lanniwu in Hule. It has been found that Dicranograptus nicholsoni diapason was associated with Dicranograptus sinensis and Climacograptus bicornis. They all occur in the upper part of the Hule Formation. The writers suggest that the Dicranograptus nicholsoni diapason zone should be the same zone as the Dicranograptus sinensis-Climacograptus bicornis zone, and therefore the name of the Dicrangraptus nicholsoni diapason may be cancelled and the Nemagraptus gracilis zone be regarded as the 2nd graptolite zone of the Hule Formation. Thus the following graptolite zones may be recognized in the Hule Formation from Hule area in a descending order.3. Dicranograptus sinensis-Climacograptus bicornis zone (Hu3)2. Nemagraptus gracilis zone (Hu2) 1. Glossograptus hincksii zone (Hu1)