Haifanggou Fm
Type Locality and Naming
The type section is located at the Haifanggou Village, Beipiao City, Liaoning Province. It was named by Beipiao Mining Bureau as the “Haifanggou Conglomerate” in 1961.
Synonym: （海房沟组）
Lithology and Thickness
It is composed chiefly of grey-yellow medium-bedded conglomerate, constituting many alternating layers together with the grey, grey-yellow and light-violet tuffaceous sandy shales and volcanic clastics, intercalated occasionally with intermediate-acidity lava and agglomerate. In the tuffaceous deposits there are often found thin coal beds or coal seams. It is with a thickness being in a range of about 654 m to 1400 m.
Relationships and Distribution
Lower contact
Its basal part is in a slight angular unconformity with the underlying Beipiao Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Tiaojishan Fm (Lanqi Fm).
Regional extent
It is distributed extensively in several large basins such as the Beipiao Basin, the Jilingsi-Yangshan Basin and the Guojiadian-Niuyingzi Basin in western Liaoning, with great changes in both its lithology and thickness from place to place. In the area of Dashuiquan, Changheyingzi Township, Beipiao City in the northern segment of the Jinlingsi-Yangshan Basin the formation represents a set of tuffaceous gritstone, pebble-bearing sandstone and andesitic conglomerate, intercalated with siltstone and mudstone, yielding abundant plant fossils, with a thickness of about 412 m; in the areas of Lamagou and Beiptaizi, Langtugou, Chaoyang County in the middle segment of the Jinlingsi-Yangshan Basin the present formation represents conglomerate, pebble-bearing sandstone and silty shale, yielding bivalve, fish, insect, plant and spore-pollen fossils, containing few volcanic materials, with a thickness of only 110 m; in the area of Shajingou till Pandaogou of Nanpiao Township, Jinxi City in the southern segment of the basin the formation represents two sets of normal sedimentary layers intercalated with one set of volcanic rocks and their clastics, and yields many kinds of animal and plant fossils, with a thickness of 887 m; in the area of Dizangsi, Yixian County within the Fuxin-Yixian Basin, the present formation contains only tuffaceous conglomerate, intercalated with sandy shale, yielding silicified wood, with a thickness of about 200-350 m. In the area of Guojiadian-Niuyingzi of Lingyuan County, the formation represents mainly a set of sandy conglomerates, intercalated with shale, coal beds and coal seams, yielding abundant animal, plant and sporo-pollen fossils, with a thickness of about 280-580 m.
GeoJSON
Fossils
It yields plant fossils in about 30 genera and more than 60 species, belonging to a middle-stage assemblage of the Coniopteris-Phoenicopsis flora. In addition, there are also found over 60 kinds of insects, whose representative members are: Sunoplecia liaoningensis, Arcus ovatus, Mesoneta antiqua, Mesobaetis sibirica, and Samarurua gigantean. In addition, there are found bivalve, Conchostracans and spore-pollen fossils.
Age
Depositional setting
The formation belongs to alluvial-fan and fluvial-lacustrine deposits associated with volcano-eruptive accumulations.
Additional Information