Tenggeer Fm

Erlian Basin. [NOTE: Kosenko et al., 2021, did not separate a Tenggeer Fm in their synthesis.]

Lower Tenggeer is mainly mudstone; Upper Tengger is interbedded mudstone and sandstone. "The Lower Tenggeer Formation with a maximum thickness of ca. 1,250 m, contains the most important source rocks of the Erlian Basin. The formation contacts the Upper Aershan Formation with an angular unconformity (named as T8 in seismic reflection sections), and is characterized by thick-bedded lacustrine mudstone, interbedded with thin layers of carbonaceous mudstone, siltstone, sandstone, and intermediate-basic volcanic rocks. In some local areas, this formation is a typical fining-upward sequence, made up of conglomerate- and pebbly sandstone-dominated basal beds and mudstone- and sandstone-dominated upper beds. The Upper Tenggeer Formation with a maximum thickness of ca. 1,350 m, contacts the Lower Tenggeer Formation with an angular unconformity (named as T6 in seismic reflection sections), and is a fining-upward sequence, containing a alluvial fan–fluvial pebbly sandstone- and sandstone-dominated lower succession and a lacustrine mudstone- and siltstone-dominated upper succession in most sub-basins of the Erlian Basin. In some sub-basins, such as the Abei-Anan Sag, the coarse-grained lower succession of the Upper Tenggeer Formation was absent, and the fine-grained upper succession rested on the Lower Tenggeer Formation directly."