Tyokar Fm

The type section is located in the alignment of Supodilei-Annazangka of Tyokar County, Xiaobangda Region, Mangkang County, Tibet. It was named by the 3^rd Regional Geological Survey Party under the Sichuan Bureau of Geology and Mineral Resources in 1974.

Synonym: Jiaoga Fm (spelling)

Limestone, Clastics and Volcaniclastsics. Composed of two lithologic associations, with a more greatly changeable lithology. The Supodilei association is represented by the section at Supodilei where it is composed mainly of grey-white and light-grey thick-bedded and massive limestones, intercalated with a small amount of calcareous shale and grey-green sandstone, with a thickness of 95 m. The Zhasuosu association is represented by the Zhasuosu section at the Annazangka, where it is composed mainly of yellow-green and grey-green thin-bedded clayey siltstone, tuffaceous conglomerate, crystal-clastic tuff, tuffaceous lava and andesitic basaltic lava, intercalated with medium- and thin-bedded bio-limestones, with a thickness of 213 m. In the Leiwuqi area it has a thickness of 1081 m.

Supodilei association yields Fusulinida fossils such as Chusenella, Praesumatrina, Neoschwagerina, Verbeekina, etc., and Ammonoids fossils such as Agathiceras sp.

Zhasuosu association yielding Fusulinida represented by Praesumatrina and Ammonoids such as Agathiceras, Artinskia and Stacheoceras. In the Leiwuqi area it yields also abundant Fusulinida fossils comprising Chusenella, Afghanella, Pseudofusulina, Verbeekina, Neoschwagerina, Metadoliolina, Sumatrina, Yabeina, and Schwagerina, etc.; Coral fossils such as Ipciphyllum, Tachylasma, Allotropiophyllum, Wentzelella, Bradyphyllum and Timorphyllum; Ammonoids represented by Agathiceras.