Hongshuizhuang Fm
Type Locality and Naming
Jixian County, Tianjin. The Hongshuizhuang Fm. was named by Gao Zhenxi (Kao, C. S.), Xiong Yongxian (Hsiung, Y. H.) and Gao Ping (Kao,P. ) in 1934. The type section is the Hongshuizhuang and its southeast area, Jixian, Tianjin Municipality.
Synonym: （洪水庄组）
Lithology and Thickness
The formation is changeable in thickness and stable in lithological character. Lower part is composed of thin-bedded dolomite sandwiched with shale. Middle part is shale. Upper part is shale intercalated with dolomitic limestone, sandstone and siltstone. In the type area, it is composed of grey-black and grey-green illite shale. The lower part is sandwiched with thin-bedded dolomite with scattered pyrite and chert concretions. The upper part consists of thin-bedded quartzose sandstone, with plane-straight bedding and widely developed carbonate concretions. Total thickness is recorded to 131 m.
Relationships and Distribution
Lower contact
The basal boundary is set at the top surface of a thick or very-thick stromatolite- bearing glauconitic dolomite (top of Wumishan Fm), and this is a conformable contact.
Upper contact
It has a conformable contact with overlying Tieling Fm
Regional extent
Tianjin, Beijing, Hebei, west Liaoning. The formation is distributed only in the Yan-Liao region. In Yanshan Region: sometimes it is absent, such as in Luanxian County. It is of black shale with pyrite and siderite concretions, with larger thickness, around Nankou, Miyun, Xinglong and Kuancheng counties, where the thickness increases, for example, to 129 m in Kuancheng County. The thin-bedded sandstone and siltstone greatly increases in Xuanhua-Yixian counties, where there is great amount of siliceous and iron concretions. In western Liaoning, it has limited distribution, where it is exposed only in Lingyuan (183 m), Jianchang (92 m), Jianping (71 m), Chaoyang (60 m).
GeoJSON
Fossils
In Lingyuan it has rich microplants. The microplant taxa: Leiopsophosphaera solida, Nucellosphaeridium zonale, Triangumorpha striata, Quadratimorpha ordinata, Leiofusa bicornuta, Glottimorpha ordinata, etc. There is also the macroalgae Chuaria.
Age
Depositional setting
Additional Information
The paleomagnetic polarity during Hongshuizhuang Fm deposition was positive, with the paleomagnetic pole situated at 45.6°N, 89.2° (by Zhang Huimin et al., 1991).