Changyang Fm
Type Locality and Naming
The type section is located lies on the right side of the Linxiangxi Highway, halfway from Taoshan to Yuxiakou (highway), Ziqiu Town, Changyang, Hubei Province; the reference section is at Tizikou, Maohu Township, Zhicheng City. It was named by Xu Souyong and Yang Deli in 1984.
Lithology and Thickness
Claystone and Sandstone. Dominated by gray-black lamellar mudstone, siltstone and gray-white, gray-brown quartzose sandstone, sometimes intercalated with coal streaks and small limestone lenses (0.17−0.20 m thick), containing pyrite and siderite nodules, 7−12 m thick.
Relationships and Distribution
Lower contact
Conformable contact with the underlying Xiejingsi Fm (Devonian)
Upper contact
Conformable contact with the overlying Ziqiu Fm
Regional extent
Distributed in the areas west of Jiangling County of western Hubei and northwestern Hunan, with little variation in rocks, which are mainly clastic rocks and mudstone. However, the intercalated limestone lenses are unstable, turning from 2−3 layers to 1 layer and finally dying out in places starting from Jianshi County eastward to Songzi County. The thickness is the maximum around Yidu County, being 12 m, as thin as 7 m in Badong, and generally 9−10 m in other places.
GeoJSON
Fossils
The mudstone and siltstone in the Upper part contain abundant fossils of brachiopods, ostracods and Spores, which are the Schuchertella gelaohoensis-Leptagonia analoga assemblage, Bairdia casta-B. profusa assemblage and Spelaetrilets pertiosus-Cingulizonates capistratus zone; those in the Lower part contain the Spores Vallattisporites verrucosus-Retusotriletes incohatus zone; in the intercalated limestone lenses are found Conodonts Siphonodella levis-Polygnathus inornatus zone and coral Syringopora ramulosa, Brachiopods Chonetes cf. ornatus, Plicattifera sp., etc.
Age
Depositional setting
It is interpreted as a littoral-gulf facies
Additional Information