Fangyan Fm
Type Locality and Naming
Eastern Zhejiang. The Zhejiang Petroleum Geological Team erected the Fangyan Formation in the summation of petroleum geological work of Zhejiang (unpublished) in 1959. The section on which the formation was erected is at Fangyan of Guantou of Yongkang, Zhejiang. The reference section is from Guantou to Shizhu of the Yongkang County, Zhejiang.
The Fangyan Conglomerate once erected represents the conglomerate beds of piedmont deposition, which was defined as Cretaceous age. In 1962 the Zhejiang Regional Geological Survey Team renamed it the Fangyan Formation and attributed to Early Cretaceous. In 1980 Ju Tianyin et al changed the Yongkang Fm to the Yongkang Gr, which included the Guantou Fm, Chaochuan Fm and Fangyan Fm and also attributed to Early Cretaceous.
Lithology and Thickness
The Fangyan Formation is mainly represented by a set of purple red massive sandy conglomerate and conglomerate beds, with a layer of light gray and black tuffaceous medium and coarse-grained sandstone. It is 1734.90 m thick.
Relationships and Distribution
Lower contact
The base of the formation comprising gray purple moderately thick-thick-bedded sandy conglomerate is differentiated from the underlying Chaochuan Fm consisting of gray purple moderately thick-thick-bedded sandy conglomerate interbedded with calcareous fine sandstone and siltstone. The Fangyan Formation is in conformable contact with the underlying strata.
Upper contact
Keshan Fm is the next younger in region; then major non-deposition.
Regional extent
The formation occurs extensively in Zhejiang and is mainly concentrated in the Wuyi-Zhuji area, the Jiangshan-Xiakou basin, Wuyi and Yongkang basin, Yiwudeshengyan- Hutoushan of Zhuji, Maanshan of Shaoxing, Dagangtou of Lishui-Nanmingshan, the Ningbo basin in southeast Zhejiang. Although it is persistent in lithology, there is a large number of sandstone partings; in Houlingshan of Dongyang, there occur gray silty mudstone of several tens of meters thick in the upper part of the formation in Gaoping of Shuichang. In Jingling-Qiaoshan of Xinchang there are two layers of relatively persistent acidic breccia tuff. The formation varies greatly in thickness and does not generally exceed 1000 m. But it is only 125 m thick and up to 1734.9 m at maximum in Maanshan of Shaoxing.
GeoJSON
Fossils
Fossils like estherias Neodiestheria jinkengensis, Yanjiestheria brevis, Y. sinensis; floras Frenelopsis sp. etc. are yielded in the purple red and grey siltstones above the conglomerate.
Age
Depositional setting
Additional Information