Xiangshuyuan Fm
Type Locality and Naming
The name was proposed by Yang Yugang, Rong Jiayu et al in 1970 (Nanjing Institute of Geology and Paleontology, Academy of China, 1974). The type section is situated near Xiangshuyuan, 2 km north of the Shiqian County seat in northeast Guizhou Province.
Synonym: (香树园组)
Lithology and Thickness
The formation, approximately 80-160 m in thickness, is dominated by a suite of knotty marl, bioclastic limestone and pelite.
Relationships and Distribution
Lower contact
The base is distinguished with brownish yellow thick-bedded marl is in a conformable contact to the underlying blackish gray graptolite shale of the Longmaxi Fm.
Upper contact
The top boundary of the formation in a conformable contact to the base of the overlying Leijiatun Fm and is marked by the appearance of yellowish green, grayish green shale.
Regional extent
It is distributed in northeast Guizhou, northwest Hunan and southwest Hubei. According to the lithology and faunas it belongs to marl facies (Yinjiang type). The Baisha type exposed along the northeastern margin of the central Guizhou uplift (covering Shiqian, Sinan, Fenggang and Zheng'an) is characterized by marl intercalated with shell limestone and reef limestone and bears abundant brachiopod Pseudoconchidium (=Paraconchidium), fasciculate and massive tetracoral Ceriaster, Stauria, etc. and tabulate, heliolite, stromatopor, algae as well. The Yinjiang type is distributed far from the northeastern margin of central Guizhou continent (e.g. in Yinjiang, Wuchuan, etc.); in comparison with the Baisha type, pelitic content considerably increases but the calcareous content decreases; instead of Pseudoconchidium there appear "Stricklandia", Merciella among brachiopods.
GeoJSON
Fossils
Among tetracoral, the simple ones are dominant (e.g., Rhizophyllum, which were suited to the life on the pelitic sea floor); fasciculate tetracoral and tabulat disappeared in general, therefore, instead wide, mushroom-shaped and crustiform elements as ecotype products occurred. In addition, graptolites appeared in the interbeds.
Age
Depositional setting
Additional Information