Sanmianjing Fm
(12), early Middle Permian
Type Locality and Naming
The type section is located at the Sanmianjing in the northern part of the Kangbao County, Hebei Province (114°48′, 42°04′). It was named by Ju Ziyun in 1959, and was cited officially by Sheng Jinzhang in 1962.
Lithology and Thickness
Clastics and Limestone. Its basal part is composed of grey-yellow sandy conglomerate. Lower part is composed of cherty-banded limestone, yielding Fusulinida, corals and brachiopods fossils. Upper part is composed of multilayer grey-green feldspar-rich sandstone, silty plate, grey-white, grey-yellow pebbled inequigranular greywacke and plant-fragment- bearing shale. Thickness of 269-715 m.
Relationships and Distribution
Lower contact
Unconformable contact with the underlying quartz-diorite in the type section. In the Maodengaobao area in the northern part of Heishatu District, Naomugen Country, Siziwang Banner the formation represents a continuous deposit in relation to its underlying Amushan Fm.
Upper contact
Unconformable contact with the overlying andesite of unknown age in the Maodengaobao area in the northern part of Heishatu District, Naomugen Country, Siziwang Banner. Next younger regional unit in Permian Lexicon chart in this column is the Elitu Fm sandstone/volcanics.
Regional extent
Distributed in the Naqing area of Sunite Right Banner, the Gongla Lane of the Huade County Town, the 2nd Branch of the Erlity Pastureland in the Ortholaid White Banner and Orthoblue Banner, the Bainaimiao Temple of the Siziwang Banner, and the Stud Farm in the Sanmianjing-Huangchengzi area of the Kangbao County, Hebei Province. The thickness of the formation is a bit changeable from place to place.
GeoJSON
Fossils
Fusulinida represented by Misellina ovalis, M. claudiae, Parafusulina bosei and P. splendens; Brachiopods such as Orthotichia morganiana, “Haydenella” robusta, Reticulatia huecoensis and Rugivestis kutorgae; and Corals such as Szechuanophyllum.
Age
Depositional setting
It is interpreted as a shallow-sea facies.
Additional Information