Shangzhuang Fm

Linxia Basin. The type section is located at Shangzhuang Village in Maogou, Dongyuan Township, southeast of Dongxiang County, Linxia Hui Autonomous Prefecture, Gansu Province. It was named by Li et al. (1995).

The Shangzhuang Fm corresponds to the lower part of the Member 3 of the original Linxia Fm, and was once included in the Dongxiang Bed (Xie, 1991). Li et al. (1995) named the strata Shangzhuang Fm. Due to the close lithology of Shangzhuang Fm and Dongxiang Fm, Deng et al. (2004) once incorporated it into the Dongxiang Fm. With the discovery of early Miocene fossils in the strata of Shangzhuang Fm, the name Shangzhuang Fm was re-used.

The Shangzhuang Fm is divided into two members. Lower Member is a ~12 m sequence of bluish grey carbonate-cemented medium sandstones and brownish red silty mudstones intercalated with a few mudstones. Upper Member is a ~33 m sequence of brownish red mudstone and brownish red interbedded siltstones and mudstones, and rhythmites of brownish red mudstones and light brownish red mudstones.

Insectivora: Mioechinus sp., Amphechinus sp.; Lagomorpha: Sinolagomys ulunguensis; Rodentia: Atlantoxerus sp., Paracricetulus? sp., Heterosminthus sp., Protalactaga sp., Litodonomys sp., Sayimys sp., Tachyoryctoides sp.; Proboscidea: Choerolophodon guangheensis, Gomphotheriidae gen. et sp. indet.; Perissodactyla: Aprotodon sp.; Artiodactyla: Turcocerus sp. (Deng et al., 2013).

The Shangzhuang Fm is interpreted as a set of braided fluvial to open shallow lake succession in relatively humid environment.