CAMBRIAN STRATIGRAPHY AT WANGCUN, HUNAN PROVINCE, CHINA: STRATOTYPES FOR BASES OF THE WANGCUNIAN AND YOUSHUIAN STAGES

摘要

Wangcun is an ancient town in southernmost Yongshun County, Hunan Province. The town is an important tourist destination, in part because of its long history and in part because of the attractive riparian scenery nearby along the Mongdonghe River, a branch of the Youshui River. A lengthy Cambrian section is exposed in a roadcut along the highway connecting Wangcun and Luoyixi, on the north bank of the Youshui River (Fengtan Reservoir), about 4 km southeast of Wangcun (Figs. 1, 2). The highway was constructed for the benefit of travelers arriving at the Louyixi railway station, and needing to drive from the railway station to Wangcun. The section is situated on the southeast limb of an undulating syncline, the Liexi-Zhuitun Syncline (Fig. 3). It is one of the major synclines extending through the Jiangnan Slope Belt in northwestern Hunan. Strata exposed in the middle of the syncline include those of the Upper Cambrian through Lower Ordovician. The trend of the structure is north-northeast. Cambrian formations exposed in the Wangcun section include the uppermost part of the Aoxi Formation and the lower and middle parts of the Huaqiao Formation. The Wangcun section serves as the stratotype for both the Wangcunian and the Youshuian stages of the Cambrian, and has recently been the subject of papers by Peng et al. (1995) and Peng and Robison (2000). The Wangcun section is easily accessible by driving west for 48 km on the Zhangjiajie-Yongshun provincial highway from Zhangjiajie to Shiti. Turn left (south) at the T-junction with the Shiti-Wangcun highway, and drive 46 km toward Wangcun until reaching a T-junction with the Wangcun-Luoyixi highway at the east end of the town of Wangcun. At the junction, turn left again (southeast) and follow the highway 5 km to a large bridge over the Fengtan Reservoir (Youshui River), There is another T-junction at the location of the section. The section extends to the northwest along the highway (Fig. 4). The section can be also reached by train travel from either from Zhangjiajie in the north, or from Jishou in the south to Luoyixi; from Luoyixi, it is a 4 km drive to the section. Alternatively, the section can be reached by driving 70 km north from Jishou (Route 3a, Fig. 1).