Duanji Fm
Type Locality and Naming
It was named by the Geological College of Beijing in 1959-1961. The naming section is located in the area from Sanliping of Shangcheng County to Duanji of Gushi County, Henan Province; with its reference section being situated in the area from Wumiao to Xiazhuanzi, Gushi County.
Synonym:（段集组）
Lithology and Thickness
Lower part is predominated by purple thick-bedded conglomerate and sandy conglomerate, intercalated with medium-, and coarse-grained feldspar-sandstone. Upper part represents yellow, violet-grey and red crystal lithic tuffs, brecciated tuffs and tuffaceous sediments, intercalated with sandy conglomerate. No fossils have been found there. Its total thickness is of 2797 m.
Relationships and Distribution
Lower contact
Its basal part unconformably overlies the Zhuji Fm
Upper contact
No top has been found. Regionally, the schematic strat column indicates the next younger unit as Wennan Fm
Regional extent
It is distributed essentially in the areas of Shangcheng, Gushi and Guangshan Counties. To the east of Shangcheng County there occurs a set of purple thickly-stratified conglomerate, medium-, and coarse-grained sandstones, with much more volcaniclastics occurring upwards. Westerly till the area of Sanliping there occurs purple thick-bedded sandy conglomerate, intercalated with thin-bedded siltstone. The volcaniclastics found in the upper part are wanting here, with a thickness of about 1448 m.
GeoJSON
Fossils
In the area of Maji, Huaibin County this formation yields Jurassic spore-pollens as proved by drillings, of which the fern spores are represented by Cyathidites minor, Camptotriletes sp., Osmundacidites sp., Lycopyodiumsporites sp., Sphagnumsporites sp., and Neoggerathiopsidozonaletes sp., while the gymnosperm pollens are represented by Pagiophyllumpollenites, Psophosphaera, Alsporites, Piceites, Podocarpidites, Abietineaepollenites and Pinuspollenites.
Age
Depositional setting
This formation belongs to alluvial-fan and fluvial deposits, intercalated with volcanic eruptive deposits.
Additional Information