Zhagashan Fm

The second area survey team of Sichuan Geological Bureau named it in 1975. The named section is located in Zaga Mountain, southwest of Songpan County, Sichuan Province. In 1961, based on the Zagnao profile in Lixian County, Sichuan Province, a set of metamorphic sandstone laminated rocks in the west of Sichuan was named Zagnao Formation by the survey team in the second area of Sichuan Geological Bureau. In 1975, the Zagashan section southwest of Songpan, Sichuan Province was used as the model, and the strata corresponding to the lower member of Zagnao Fm (=Zagunao Fm in this Lexicon usage) were named as the Zagashan Formation. In 1987, Rao Rongbiao et al., in view of the discovery of Daonella lommeli and other standard Ladinian fossils in the lower part of the Zagenaenao Fm, divided it into the Zagashan Fm, also known as the Zhagashan Formation, which was dated from the Middle Triassic Anisian-Ladinian. This Lexicon follows this meaning.

Synonym: Zagashan Fm

It is composed of carbonate rocks and clastic rocks. Lower part is mainly yellowish-gray thin layer argillaceous limestone and gray-green and purplish-red slate with frequent rhythmic layers, with a thickness of 35.4 m. In the middle is a gray thick layer of dense limestone, rich in the Traumatocrinus sp. of sea lily (crinoid), often dense reef limestone, thick 299 m. Upper part is composed of a complex rhythmic layer of grey calcareous quartz sandstone, slate and thin or lentiform crystalline limestone, 702 m thick.

The fossils include bivalves, brachiopods, crinoids, gastropods and conodonts