Anmin Fm
Type Locality and Naming
This formation was named as the “Anmin Coal-bearing Strata” by the No. 104 Party under the No.1 Northeast China Coalfield Prospecting Bureau in 1965. And in 1962 it was cited publicly as the Anmin Formation by Si Xingjian and Zhou Zhiyan. The naming section is located in the vicinity of the Anmin Village in Pinggan Coal Mine, Dongliao County, Liaoyuan City, Jilin Province, with its reference section being situated in the area of the Defeng Village of Pinggang region (Huoshanzhui-Xiaobai Quan).
Synonym: （安民组）
Lithology and Thickness
Lower part is composed of milky white rhyolite, with a thickness of about 400 m. Middle part is grey-green andesite and sandstone, intercalated with black-grey carbonaceous shales and thin coal seams, with a thickness of 138 m. Upper part is grey-green, grey-violet basalt, and andesitic and rhyolitic tuffs, with a thickness of about 108 m.
Relationships and Distribution
Lower contact
It is in a conformal contact with the underlying Jiuda Fm
Upper contact
Regionally, the next younger unit is indicated as Chang'an Fm (not in Lexicon entries yet)
Regional extent
It is distributed essentially in the areas of Liaoyuan, Pinggang and Dongfeng seated at the border between Jilin and Liaoning provinces, with its sporadic exposures being found in other basins. It is composed largely of andesite and rhyolitic volcanic clastics, intercalated occasionally basaltic andesite, black mudstone and coal layers or coal seams. The total thickness of the formation is of 500-1200 m.
GeoJSON
Fossils
It yields plant fossils as represented by Equisetum sp., Ginkgo digitata, G. sibirica, Sphenobaiera czekanowskiana, Czekanowskia rigida; in the Liaoyuan Basin it yields Coniopteris burejensis, Nilssonia sp., Baiera pseudogracilis, Podozamites sp. Brachyphyllum sp. in the Pinggang area.
Age
Depositional setting
The Anmin Formation belongs to intermediate volcanic-eruption facies and represents fluvial-swamp deposits formed during the dormant period of volcanic eruption.
Additional Information