Xiahuayuan Fm
Type Locality and Naming
It was named by Tian Benyu, Yang Zhijia as Xiahuayuan Series in 1950, and was first cited publicly by the Compiler
Jingeng Sha (coordinator) Group for the Regional Stratigraphic Chart of Hebei Province and Tianjin City. The naming locality is situated in the Xiahuayuan area of Zhangjiakou City, Hebei Province, with its reference section being situated at Cuijiazhuang of the Xiahuayuan area, Zhangjiakou City.
Synonym: （下花园组）
Lithology and Thickness
Lower part is composed of grey-green, grey-yellow and yellow-green sandstones, fine-grained sandstone, grey-black silty shale and carbonaceous shale, intercalated with pebble-bearing gritstone, marl and mineable coal beds. Upper part is composed of grey-green and grey-yellow sandstones, intercalated with conglomerate, silty shale, shale, thin coal beds and coal seams, with a total thickness of it varying from 27 m to 1018.8 m.
Relationships and Distribution
Lower contact
Its basal part commonly unconformably overlies the pre-Sinian System, Sinian System or Paleozoic Erathem. In a small number of regions, the formation is in a disconformable contact with the underlying Nandaling Fm
Upper contact
In a small number of regions, the formation is in a disconformable contact with the overlying Jiulongshan Fm, or with no top part of it having been found.
Regional extent
NW of Beijing. The formation is distributed in the Hongtuliang area of Shangyi County, Xiahuayuan area of Zhangjiakou City, Gufangzi area of Chicheng County, Laowa, Xiabancheng and Pingquan areas of Luanping County, Damiaoliang and Weichang areas of Chengde City in northern Hebei. Both the lithology and thickness of the formation are changeable from region to region. In the Xiahuayuan area on the south it is composed largely of a set of lacustrine and swamp-facies coal-bearing clastic deposits, with a thickness of 327-470 m; while in the Jiajiazhuang and Cuijiazhuang areas on the north its lower part is composed of coarse clastic deposits, and its upper part is composed of finer clastics and yields coal seams and coal beds, with a thickness of about 1193 m. NOTE: Seems coeval with upper part of the Mentouguo Gr (Yaopo Fm and Longmen Fm ) of Beijing region.
GeoJSON
Fossils
The formation is rich in plant fossils, with bivalve fossils being secondary. The plant fossils comprise Baiera furcata, B. asadai, Voniopteris hymenophylloides, C, burejensis, C. tatungensis, Cladophlebis haiburensis, Cl. fangtzuensis, Cl. shansiensis, Clathroptersi pekingensis, Czekanowskia rigida, C. setacea, Ctenis kanhardi, Equisetites lateralis, Ginkgoites sibiricus, Nilssonia princeps, N. mosserayi, Neocalamites hoerensis, N. carrerei, Pityophyllum longifolium, Todites denticulate, T. williamsoni, Sphenobaiera latus, Hausmannia leeiana, Dictyophyllum cf. nilssoni, Otozamites bechei; and bivalve fossils comprise Ferganoconcha sibirica, F. sibirica sublata, F. tomiensis, Sibireconcha golovae, S. cf. anodontoides, Pseudocardinia? cf. ovalis and P. cf. turfanensis.
Age
Depositional setting
Additional Information
Age:
"Early-Middle Jurassic". Stratigraphic relationships disconformable below Jiulongshan Fm and disconformable above Nandaling Fm volcanics.
Age span:
Beginning stage: Aalenian
Fraction up in beginning stage: 0.0
Beginning date (Ma):
Ending stage: Callovian
Fraction up in ending stage: 0.5
Ending date (Ma):
Depositional setting:
Depositional-pattern:
Additional Information
Compiler
Jingeng Sha (coordinator)