Liwaxia Fm

Its base marked by purple sandy mudstone interbedded with gray green mudstone is distinguished from the underlying Heshangpu Fm. It shows a conformable contact with the underlying strata.

Its top marked by gray green and purple red marl differently thick interbedded with gray and brown calcareous shale is bounded by the overlying Madongshan Fm. It shows a conformable contact with the overlying strata.

The present formation occurs in the Liupanshan area and is most developed in the Heshangpu-Lijiawa area of the Guyuan County of Ningxia, with its finest lithology. It is of shore-deep lake facies with a thickness of 901.79 m. It becomes coarser in lithology out wards from the central basin, being of fluvial-lacustrine alternating deposition and decreasing in thickness. In Mengjiatai of Huating of Gansu, it is represented by purple (with variegated) mudstone, marl, limestone and small amounts of quartz sandstone, richly bearing calcareous matters, with a thickness of 303 m. In the Anguo town, it decreases in purple color and grades into yellow green, gray green, blue gray and gray white clayey shale, with a thickness ranging from 90 to 133 m. In Guguan of Longxian of Shaanxi it is represented by a set of purple red conglomerate, gravel-bearing sandstone, sandstone and sandy mudstone interbedded with one another, with its top being cut off by faults and with a thickness up to 1572 m at maximum, belonging to piedmont and fluvial deposition. The present formation has cuprous sandstone and uranium mineralization beds and is also a good oil-bearing formation.