Meitan Fm
Type Locality and Naming
The type section is at Wulipo 8 km west of Meitan City, Guizhou. The Meitan Fm is derived from the Meitan Shale proposed by Yu Jianzhang (C.C. Yü) in 1933.
According to Grabau's suggestion, Yu divided the type section into Yichang Limestone, Meitan Shale, Lesueurilla Bed, Yangtzella Bed and Orthoceras Limestone, in ascending order, and defined the Meitan Shale to be Early Ordovician. The strata equivalent to the Meitan Shale was named Yangtianwo Shale by Ding Wenjiang (V.K. Ting) and Malukou Shale by Zhang Mingshao and Sheng Xinfu (1940). In 1962, Zhang Wentang included Lesueurilla Bed and the lower part of the Yangtzella Bed in the Meitan Shale, and renamed it as the Meitan Shale Fm. In 1964, he included the whole Yangtzella Bed in the Meitan Shale Fm, and in turn renamed it the Meitan Fm. In 1965, Wang Xiaofeng suggested that the previously defined Meitan Shale should be maintained, and named its upper part the Longzuiba Fm. Guizhou Bureau of Geology and Mineral Resources (1987) divided Zhang's (1964) Meitan Fm into Malukou Shale Member in the lower part and the Longzuiba Member in the upper part. The present book follows Zhang's (1964) suggestion.
Synonym: (湄潭组)
Reference Section:
The reference section is at Honghuayuan 7 km south of Tongzi City (Guizhou Bureau of Geology and Mineral Resources, 1987). The reference section is 251 m thick.
Lithology and Thickness
The Meitan Fm is divided into two members. Lower member (Malukou Shale Member) is dominated by grayish green, yellowish green shale intercalated with siltstone, sandy shale and lenticular or thin-bedded bioclastic limestone. Upper member (Longzuiba Member) is composed of interbedded thin- to medium-bedded limestone, bioclastic limestone or nodular limestone and sandy shale.
Relationships and Distribution
Lower contact
The Meitan Fm rests conformably on the limestone of the Honghuayuan Fm. In most areas above mentioned, a conformable contact between the Meitan Fm and the underlying strata is observed.
Upper contact
It is conformably overlain by the oolitic to pisolitic limestone at the base of the Guniutan Fm. In most areas above mentioned, a conformable contact between the Meitan Fm and the overlying strata is observed. But in areas west of Zunyi to Yejiao west of Bijie City and Heinijing north of Bijie City, its upper part is denuded, and the Meitan Fm is disconformably overlain by the Carboniferous or Permian (Guizhou Bureau of Geology and Mineral Resources, 1987).
Regional extent
From bottom to top and from west to east, the Meitan Fm show a lithological variation of decreasing clastic and increasing calcareous sediments. It is generally 180-260 m thick, and is exposed in northern Guizhou, southern Sichuan and southern Guizhou (114-338 m thick) and northeastern Sichuan (53 m thick). Additionally, from drilling data, in Huaying Mt. and Weiyuan also find the Meitan Fm about 200 m thick. The Yingpan Fm (Member) together with the overlying Houping Fm (Member) (Chen Junhan et al., 1989) in northeastern Sichuan is equivalent to the Meitan Fm.
GeoJSON
Fossils
It yields abundant graptolite, chitinozoan, conodont, trilobite and brachiopod. The lower member includes four graptolite zones, in ascending order, Didymograptus filiformis range-zone, Didymograptus eobifidus / protobifidus acme zone, Didymograptus deflexus acme zone and Azygograptus suecicus range-zone. Graptolite Undulograptus austrodentatus range-zone and cephalopod Protocycloceras deprati range-zone have been established in the middle-upper part and the lower part of the upper member respectively. A.W. Grabau and Yu Jianzhang studied the fossils from the type section.
Age
Depositional setting
Additional Information