Jiuliping Fm
Type Locality and Naming
The type section is located nearby Jiuliping, north of Hujiayuan in Shanyang County, Shaanxi Province; the reference section is at Nanchanggou to Laogou in Shanyang County. It was named by Shaanxi Team of Regional Geological Survey in 1959 during mapping the “Shaangxian Geological Map (the scale is 1:200000)”, and formally quoted by Wang Yu et al in 1962.
Lithology and Thickness
It can be divided into two members.
Sandstone. Lower member, 802 m thick, is composed of brownish-gray to gray, medium-bedded and thin-bedded calcareous fine- to medium-grained feldspathic quartzose sandstone and quartzose sandstone intercalated with silty slate and minor thin-bedded sandy limestone.
Claystone. Upper member, 877 m thick, is mainly characterized by rhythmic interbeds of dark-gray and greenish-gray calcareous sericitic silty slate, sericite silty slate and thin- to medium-bedded calcareous feldspathic quartzose sandstone and thin-bedded sandy limestone.
Relationships and Distribution
Lower contact
The section of the formation from Changgou to Laogou is fairly complete and has a conformable contact to the underlying Xinghongpu Fm.
Upper contact
The section of the formation from Changgou to Laogou is fairly complete and has a conformable contact to the overlying Jiehejie Fm of earliest Carboniferous.
Regional extent
The Jiuliping Fm is widely distributed in the areas from Fengxian to Daibai and Zhen’an to Shanyang; in the east, the strata exposed north of Yunzhen-Kuanping (Zhashui) fault which used to be treated as the upper member of the Jiuliping Fm should be delimited to the Gedasi Fm. The Jiuliping Fm at Chajiagounao in Zhen’an County, more than 882 m in thickness, is composed of sandy slate intercalated with fine-grained sandstone, thin-bedded limestone and minor conglomerate, yields coral Philipsastea; bivalve Buchiola and brachiopod Yunnanellina etc. and should be equivalent to the upper member of the Jiuliping Fm. In the west, this formation outcrops rather completely with a thickness of more than 1788 m at Qiantongshan in Fengxian County where it conformably overlies the Xinghongpu Fm. Here, it is dominated by medium- to fine-grained feldspathic quartzose sandstone which composes rhythmic interbeds together with silty slate and sandy crystalline limestone; and the lower part yields brachiopod Atrypa, coral Alveolites, Chaetetes etc.; and, in general, it can be correlated with the exposures in the east.
GeoJSON
Fossils
The upper part of this upper member yields Conodonts Palmatolepis glabra distorta, Pa. g. elongata, Pa. minuta and Apatognathus
Age
Depositional setting
It is interpreted as a beach flat to restricted basin.
Additional Information