Changhia Fm
Type Locality and Naming
The type section of Changhia Formation is Hutouya-Huangcaoding section on the east of Gushan Hill near Gushan Town, Changqing, Jinan, Shandong Province (116°52’06” E, 36°30’02” N). It lies about 5 km northwest of Zhangxia Town or 8 km of east of the seat of Changqing County and was remeasured by Zhang Zengqi et al. in 1992. The formation in the type section is 177.55 m thick. The Changhia Formation was named by Blackwelder (1907). The name is derived from Changhia (now spelled Zhangxia in Hanyu Pinyin) Town in Changqing District, Jinan City, northwestern Shandong Province. Blackwelder originally called the formation Changhia limestone, referring it to the first lithologic unit of his Kiulung group. Subsequently, it was called the informal Changhia formation by Sun (1924), the Changhia Series by Lu and Dong (1952), and the Changhia Formation by the Compiling Committee for Geology of China and Institute of Geology, Chinese Academy of Sciences (1956). Subsequently this unit was adopted as a Chinese standard Cambrian chronostratigraphic unit, the Changhian Stage (Xiang et al., 1981; Zhang, 1985; Compiling Committee for Chinese Stratigraphic Lexicon et al., 1999), and had been used for a long time until a new four-fold chronostratigraphic subdivision was introduced (Peng, 2000a, b).
Synonym: （张夏组）
Lithology and Thickness
The Changhia Formation is distinct in lithology, mainly consisting of light grey, grey thick-bedded limestone, massive crystalline limestone and algae limestone, alternated with black thin-bedded limestone, oolitic limestone and massive limestone. In the type section, the formation can be divided into two members of carbonate sequence, the Lower Limestone Member and the Upper Limestone Member. Lower member mainly comprises dark grey, thick-bedded oolitic limestone, limestone breccia and crystalline limestone with yellow dolomitic strips or lumps (62.89 m). Upper member mainly comprises dark grey, thick-bedded algal limestone, oolitic limestone and yellowish green argillaceous limestone (114.66 m). In Shandong Province, the areas east to the type area of the formation, the Changhia Formation shows a three-folded division with adding a member, the Panchegou Member, between the lower and upper limestone members. The type section of the Panchegou Member is located near Panchegou Village in Wennan Township, Xintai county-level City, central Shandong Province, where the member comprises mainly fine clastic sequence with yellowish green shale, intercalated with thin-bedded micritic limestone.
Relationships and Distribution
Lower contact
The Changhia Fm is regarded to be rested conformably on the underlying Manto Fm. As noted by Zhang in Zhang and Liu (1996), there is actually a depositional break between the Manto and Changhia formations, although the time breaks are very short and result no distinct hiatus of stratum.
Upper contact
Regarded to be overlain by the overlying Kushan Fm. As noted by Zhang in Zhang and Liu (1996), there is actually a depositional break between Changhia and Kushan Formation as well, although the time breaks are very short and result no distinct hiatus of stratum.
Regional extent
Except for the Western Margin Area, the Changhia Formation is exposed in all other areas of the of North China Region, i.e., the Shanxi-Henan-Shaanxi, Xuzhou-Huaibei, Western Shandong, Northern Hebei-Western Liaoning and Liaoning-Jilin areas. It is distributed widely over nearly whole the North China platform, including Jilin, Liaoning, Ningxia, Gansu, Shaanxi, Hebei, Shandong, Shanxi, Henan, northern Anhui and northern Jiangsu provinces, and Inner Mongolia Autonomous Region. It is strikingly characterized by its fairly stable lithology and oolitic limestone.
GeoJSON
Fossils
Formation yields diverse polymerid trilobites and a few of agnostoid trilobites. Yuan et al. (2012) reported 152 trilobite genera (subgenera), which including 134 polymerid genera (subgenera) and 18 agnostoid genera (subgenera). The common polymerids include: Ajacicrepida, Amphoton, Anomocarella, Bailiella, Baojingia, Changqingia, Crepicephalina, Cyclolorenzella, Damesella, Dorypyge, Eosoptychoparia, Eymekops, Fuchouia, Honania, Houmaia, Huayuanaspis, Inouyella, Inouyops, Inouyia, Iranochresterius, Iranoleesia, Jiulongshania, Kaipingella, Lioparia, Liopeishania, Lisania, Liuheaspis, Luia, Manchuriella, Maotunia, Mapania, Megagraulos, Metagraulos, Metanomocarella , Monkaspis, Taihangshaniashania, Parablackwelderia, Paracoosia, Paranomocarella, Parayujinia, Peishania, Pingluia, Poriagraulos, Poshania, Proasaphiscus, Prodamesella, Saimachia, Solenoparina, Sudanomocarina, Sunaspidella, Szeaspis, Taitzehoia, Taitzuia, Teinistion, Tonkinella, Xingrenaspis, Yongwolia, Zhongweia, and Zhujia; and the common agnostoids include: Ammagnostus, Peronopsis, Ptychagnostus, Tomagnostus, Tomagnostella, Hypagnostus, Baltagnostus, and Utagnostus. The upper part of the Formation contains conodont Shandongodus priscus.
Age
Depositional setting
Additional Information