Marri Fm
Type Locality and Naming
It was named by Shi Xiaoying, Tong Jinnan in 1985. The naming section is located at Marri of Luolong County, Tibet (E 96°18′, N 30°54′).
Synonym: （马里组）
Lithology and Thickness
The formation is composed of purple, grey-yellow and grey-white conglomerates, fine-grained sandstones and siltstones, intercalated with sandy limestones. Lower part consisting of thick-bedded purple conglomerates, breccias and grey-white medium-bedded conglomerates, gritstones. Upper part consisting largely of grey-yellow and grey-white medium-bedded fine-grained sandstones and siltstones, intercalated with thin-bedded sandy limestones and mudstones. It is 168.4 m in thickness.
Relationships and Distribution
Lower contact
Its basal conglomerates are in an unconformable with the underlying late Paleozoic slate and phyllite. [Regionally, the next older units is the Quehala Gr of late Triassic.
Upper contact
Its top part is in a conformable contact with the basal argillaceous limestones and marls of the overlying Liuwan Fm
Regional extent
The formation is distributed largely in the middle and lower reaches of the Nujiang River and is characterized by a consistent lithology.
GeoJSON
Fossils
It yields in the Marri area bivalve fossils as represented by Protocardia stricklandi, P. maliensis, Myophorella maliensis, M. signata, Ceratomyopsis undulata, Astarte maliensis, Chlamys (C.) sp., Mactromys cf. acesta, Sphaeriola oolithica.
Age
Depositional setting
The formation represents fast accumulated nearshore and peri-shallow-sea clastic sediments, yielding bivalves and Gastropoda with a strong adaptability.
Additional Information