K-bentonite beds and high-resolution integrated stratigraphy of the uppermost Ordovician Wufeng and the lowest Silurian Longmaxi formations in South China

• Published in: Science China. Earth sciences 2003-11, Vol.46 (11), p.1121-1133
• Main Authors: Su, Wenbo, He, Longqing, Wang, Yongbiao, Gong, Shuyun, Zhou, Huyun
• Format: Article
• Language: English
• Subjects: Bentonite; High resolution; Ordovician; Palaeo studies; Platforms (geology); Resolution; Silurian; Stratigraphy; Volcanic ash; Volcanic deposits; Volcanic eruptions; Volcanoes; Work platforms
• ISSN: 1006-9313; 1674-7313; 1862-2801; 1869-1897
• DOI: 10.1360/01yd0225

More than 20 K-bentonite beds were discovered from the Wufeng Formation and the lowest Longmaxi Formation in two sections, both adjacent to the Ordovician-Silurian (O-S) boundary and located in Tongzi, Guizhou Province and Yichang, Hubei Province, some 500 km apart from each other in South China. This indicates that many volcanic eruptions occurred near the southeast margin of the Yangtze Platform between the latest Ordovician and the earliest Silurian. Mainly through biostratigraphic and sequence stratigraphic studies, it was found that almost all these far-apart K-bentonite beds may be correlated with each other. This is the first time that a succession of volcanic ash deposits with high potential of correlation was discovered within a strata interval on the main platforms of China. Therefore, these K-bentonite beds may afford excellent event-marker beds helpful to high-resolution research in integrated stratigraphy as well as other lines of research on the O-S boundary in South China.