Hongtupo Fm

Songpan region, eastern Tibet Plateau. The holostratotype is the Hongtupo section which is located in the east side of Maladun, Hongtupo Township, 30 km southwest of Songpan County, Sichuan Province. It was measured and named by the Second Regional Geological Survey Brigade of Sichuan in 1975. And described by the Bureau of Geology and Mineral Resources of Sichuan in 1987.

The Hongtupo Formation unconformably overlies the Maladun Fm and comprises thick-bedded reddish-brown conglomerates interbedded with lenticular siltstones and mudstones. The conglomerates are dominated by clasts of proximal Triassic sandstones. In the middle of the investigated Labei section, the reddish-brown conglomerates are interbedded with coarse-grained sandstones, siltstones, and nodular paleosols that crop out in a tectonic window created by a small north-directed thrust. A reddish paleosol layer, with a thickness of approximately 20 cm, interbeds in the sandstone beds and contains very small (0.3–1 cm) carbonate nodules. The uppermost portion of the Hongtupo Formation features massive clast-supported conglomerates composed of subrounded pebbles to cobbles interbedded with thick trough cross-bedded sandy conglomerates. The thickness of exposure ranges from 91-672 m. [Another entry said: " Lower part is composed of purplish-red and grayish-white thin- to medium-bedded siltstone and clayey sandstone. Upper part is composed of purplish-red, brick-red thick-bedded and massive glutenite, the grains dominated by calcareous sandstone, and also comprises vein quartz, limestone and diorite porphyrite." – but not sure if this was for the Hongtupo Fm]

No fossil have been found.

Fluvial-alluvial deposits. This large volume of massive, texturally immature conglomerates was deposited in proximally sourced alluvial fans and channels, and the paleosols developed on the short-term floodplains of the alluvial fans.