Dongying Fm
Type Locality and Naming
Bohai Bay region. The naming section is located in well Hua 8 in Kengli County, Shandong. Named by the North China Petroleum Exploration Administration, Ministry of Petroleum and formally used by Jia Zhonghui in the Comprehensive Research Report on the Petroleum Geology of the North China Plain.
Lithology and Thickness
Lacustrine deposits dominated by sandy mudstone above the Shahejie Formation. The lithology, lithofacies and thickness vary relatively greatly from place to place. The formation includes three members, which are, in ascending order: Third member is predominantly mudstone, with limy shale and sandstone interbeds. Second member is grayish green mudstone with sandstone. First member is brownish red and grayish green mudstone intercalated or alternating with sandstone, at the top of which there are usually volcanic rocks. The thickness is 300-1500 m.
Relationships and Distribution
Lower contact
This formation is continuous with the underlying Eocene Shahejie Fm.
Upper contact
Unconformable contact with the overlying Neocene Guantao Fm.
Regional extent
This formation is widespread in the Bohai Sea area, North China plain and lower Liaohe River plain. It is represented by a sequence of thick, gray and dark gray sandy mudstone, up to 1000–1500 m thick in the western Hebei plain; alternating beds of variegated mudstone and grit in the Boxing area, Shandong, only 300 m thick; alternating beds of red sandstone and mudstone in the central Hebei plain and sandstone in the lower Liaohe River plain.
GeoJSON
Fossils
Fossils in the formation are rich and have highly varied genera and species. There are such abundant groups as ostracods, gastropods, charophytes and sporopollen. Especially the freshwater to brackish biotas represented by Chinocythere have their unique characters, and in addition there appear a number of new endemic species. Among other things, the ostracods in the third member of this formation are dominated by the Chincythere unicuspidata assemblage and also include some species with undeveloped tubercule ornamentations. Gastropods are characterized by the Viviparus xinglongtaiensis-Stenothyra spiralis assemblage. Ostracods in the second member of the formation are mainly characterized by the special development of shell ornamentations and prosperity of Dongyingia with very thick shell walls and represented by the Dongyingia inflexicostata assemblage. Gastropods have relatively rich genera and species and large numbers of individuals, with basal ribs, umbilical ribs and tubercular ribs at most shell surfaces; their shells are relatively hard and there is great difference in size of individual forms. These gastropods belong to the shallow-water type and are the Tianjinospira monostichophyma assemblage. The second and third members of the formation represent an epoch when Paleogene algae were once again very prosperous, and it was especially the case with acritarchs, which have developed to their culmination in the second member of the formation and consist predominantly of the Dictyotidium-Rugasphaera assemblage. Besides those stated above, the mammal Ansomys shangtungensis (Resbergr, J.M. and C.K. Li, 1986) has also been found at the top of the formation.
Age
Depositional setting
It is interpreted to lacustrine deposits.
Additional Information