Sunjiafen Fm
(14), mid-Middle Permian
Type Locality and Naming
The type section is located to the west of the Sunjiafen area, Longjiang County, Heilongjiang Province. It was named by Liu Buchang et al., in 1973, and was cited officially by the Compiling Group for the Regional Stratigraphic Chart of Heilongjiang Province in 1979.
Synonym: Linxi Fm (see Additional Information below)
Lithology and Thickness
Clastics and Volcanics. Lower member is composed of grey, grey-white and yellow-green coarse clastic rocks, intercalated with many layers of intermediate-acidic volcanic rocks and tuff, being possessed of basal conglomerate, yielding bivalves, with a thickness of 675 m. In the Naobao Mt. area the basal part of the formation consisting of brown-grey sandy conglomerate. Middle member is composed of grey and green-grey fine-grained sandstone with oblique bedding and siltstone, intercalated with many layers of polymineralic sandstone, clayey concretions and siltstone, with the shale yielding bivalves and plant fossils (phytolites), with a thickness of 898 m. Upper member represents interbeds of black-grey and yellow-green clayey slate and fine-grained sandstone, the lower part of which is composed of brecciated silty shale and siltstone, yielding abundant bivalves, while the upper part of the particular member is possessed of many layers of polymineralic sandstone, with a thickness of 721 m. The granularity of the deposits is getting finer in ascending order, and is possessed of an obvious rhythmicity.
Relationships and Distribution
Lower contact
Disconformable contact with the green-grey clastics-bearing micrite of the underlying Liutiaogou Fm in the Naobao Mt. area
Upper contact
Regional extent
Distributed in the Laolongtou and Sanjiafen areas of the Longjiang County, the Malatu area of the Zhalaite Banner, the Halasu area of the Buteha Banner, the Luotuo Mt. of the Arong Banner, the lower reaches of the Gentu River and the Baxin River area, extending in a NE-trend.
GeoJSON
Fossils
Yields Bivalves represented by Palaeomutela semilunulata, P. ovalis, Palaeanodonta castor, P. verneuli; Plant fossils (phytolites) represented by Noeggerathiopsis, Glossozamites kryshtofovichi, Comia.
Age
Depositional setting
It is interpreted as a lake-facies clastic-rock and intermediate-acidic volcanic-rock formation
Additional Information
Lithology and Thickness:
Clastics and Volcanics. Lower member is composed of grey, grey-white and yellow-green coarse clastic rocks, intercalated with many layers of intermediate-acidic volcanic rocks and tuff, being possessed of basal conglomerate, yielding bivalves, with a thickness of 675 m. In the Naobao Mt. area the basal part of the formation consisting of brown-grey sandy conglomerate. Middle member is composed of grey and green-grey fine-grained sandstone with oblique bedding and siltstone, intercalated with many layers of polymineralic sandstone, clayey concretions and siltstone, with the shale yielding bivalves and plant fossils (phytolites), with a thickness of 898 m. Upper member represents interbeds of black-grey and yellow-green clayey slate and fine-grained sandstone, the lower part of which is composed of brecciated silty shale and siltstone, yielding abundant bivalves, while the upper part of the particular member is possessed of many layers of polymineralic sandstone, with a thickness of 721 m. The granularity of the deposits is getting finer in ascending order, and is possessed of an obvious rhythmicity.
Lithology-pattern: Fine-grained sandstone
Relationships and Distribution:
Lower contact:
Disconformable contact with the green-grey clastics-bearing micrite of the underlying Liutiaogou Fm in the Naobao Mt. area
Upper contact:
Regional extent:
Distributed in the Laolongtou and Sanjiafen areas of the Longjiang County, the Malatu area of the Zhalaite Banner, the Halasu area of the Buteha Banner, the Luotuo Mt. of the Arong Banner, the lower reaches of the Gentu River and the Baxin River area, extending in a NE-trend.
GeoJSON:
Fossils:
Yields Bivalves represented by Palaeomutela semilunulata, P. ovalis, Palaeanodonta castor, P. verneuli; Plant fossils (phytolites) represented by Noeggerathiopsis, Glossozamites kryshtofovichi, Comia.
Age:
Assigned as mid-Middle Permian
Age Span:
Beginning stage: Capitanian
Fraction up in beginning stage: 0.0
Beginning date (Ma):
Ending stage: Capitanian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
It is interpreted as a lake-facies clastic-rock and intermediate-acidic volcanic-rock formation
Depositional-pattern:
Additional Information
In 1991 the Bureau of Geology and Mineral Resources of the Inner Mongolia Autonomous Region decided to take the formation for a synonym of the Linxi Fm.