Muri Fm
Type Locality and Naming
It was named by the Muri Geological Party as the Muri Coal Series in 1956. The naming section is located in the vicinity of Muri Township of Tianjun County, Qinghai Province.
Synonym: （木里组）
Lithology and Thickness
The formation lithologically can be divided into the three parts. Lower part is composed mainly of grey-white thick-bedded and medium-, and coarse-grained quartz-sandstones, intercalated with shales and coal beds, with its base representing conglomerates. Middle part is composed largely of grey-white and grey medium-, and fine-grained sandstones, black shales and carbonaceous shales, intercalated with mineable coal beds, being 500-1100 m thick. Upper part consists of black-brown bibliolites (= laminated schist), intercalated with oil shales and siderite concretions, with a thickness of about 200 m.
Relationships and Distribution
Lower contact
It is in a disconformable contact with the underlying Upper Triassic (Nanying'er Gr, Nanyinger Gr), or overlies older strata.
Upper contact
It is in a disconformable contact with the overlying Xiangtang Fm.
Regional extent
The formation is distributed in the Muri, Cangjiang-River, Reshui and Mole areas on the upper reaches of the Datong River of Qinghai Province, with the most intensive development of it being seen in the Jiangcang region. Its lithology is largely identical but with minor differences in various regions.
GeoJSON
Fossils
The middle part yields plant fossils such as Coniopteris hymenophylloides, C. spectabilis and Ginkgoites cf. sibiricus.
Age
Depositional setting
Additional Information