Miaogou Fm

The base marked by dark red conglomerate with clayey sandstone lies unconformably on the underlying Upper Jurassic Shazaohe Fm.

The top marked by deep brown mudstone lies conformably under the overlying Jingangquan Fm.

The present formation occurs in the Chaoshui basin, the Yabulai basin and west of the Helan Mountain at the juncture of Inner Mongolia and Gansu. In the Miaogou area, the lower part of the Miaogou Formation is built up by purple conglomerate and sandy conglomerate with siltstone, while the upper part variegated shale with siltstone, marl, sandstone, sandy conglomerate and gypsum beds, ranging from 700 to 100 m in thickness. In Qinggetule, the Miaogou Formation is mainly represented by a set of brown yellow and gray yellow sandstone, conglomerate and sandy conglomerate interbedded with mudstone, measuring 1039 m in thickness. In Tatashui, the lower part of the formation is dominated by break red conglomerate, while the upper part of the formation is represented by gray white clayey sandstone with sandy mudstone, marl and gravel-bearing sandstone, about 1888 m thick. In Dongshanmiao and Quandunzi, it is represented by red and brown yellow macroclastic sediments, ranging from 300 to 700 m in thickness. In the Langwa area of Alxa Youqi, it is represented by purple red thick-bedded conglomerate with sandy conglomerate, sandstone, siltstone and mudstone, measuring 1042 m in thickness. In Changjingzi and Geda , the lower part of the formation is built by loose, yellow brown, gray white and break red conglomerate and grit, the upper part yellow green sandy conglomerate, silty mudstone and marl, while the top gray silty mudstone with sandstone and marl, measuring 1419 m in thickness. In the Jiaojiagou, Duqingshan and Hongshaquan areas of southwest Yabulai basin, the lower part of the formation is made up of purple red, break red and gray green sandstone with mudstone, sandy conglomerate and gypsum, while the upper part break red and gray white sandy conglomerate, conglomerate and sandstone, ranging from 821 to 969 m in thickness. In the Heitoushan and Sangejing areas of north Yabulai basin, it is represented by a set of red clastic rocks, ranging from 200 to 600 m in thickness. In most areas, the present formation lies unconformably on the older strata and is overlain by the Eocene or the Quaternary. The Dashuigou Fm instead of the Miaogou Fm was once used.