Beixiangshan Fm
Type Locality and Naming
It was named by Ju Kuixiang in 1985, and was first cited publicly by Wu Qiqie and others in 1986. The naming section is located in the area extending from South Xiangshan Hill to North Xiangshan Hill of Qixia Mts in the eastern suburbs of Nanjing City, Jiangsu Province; with its reference section being located in a stretch from the Zhongshan Hill to the Linggu Temple.
Synonym:
Lithology and Thickness
It is composed essentially of grey-white and purple medium, and coarse-grained pebble-bearing feldspar-quartz sandstone, lithic sandstone and muddy siltstone, intercalated with purple and grey-green silty mudstone and calcareous mudstone, containing often volcanic clastics and pebbles, with a thickness of about 600 m, and no biotic fossils have been found there.
Relationships and Distribution
Lower contact
It represents continuous deposits together with the underlying Nanxiangshan Fm (Zhongshan Fm).
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Xihengshan Fm
Regional extent
It is distributed mainly in a belt extending from Nanjing City to Jiangning City. In northern Jiangsu Province it can be proved to occur by drilling wells. The lithology of it has less changes, yet the thickness of the strata varies more or less greatly from place to place. As in the North Xiangshan Hill the thickness of the formation is of about 612 m; in the area of Shangcun Village, Jiangning City, of about 507 m; in the zone from Zhongshan Hill to the Linggu Temple, of more than 169 m; at Yangfang, of about 157 m; in the areas of Changzhou, Jiangdu and Funing the thickness of the formation determined on the basis of the data collected from the drilling wells there varies from 200 m to 300 m. At the base of the formation there occurs a layer of pebble-bearing sandstone, which makes the formation easier to differentiate itself from the Nanxiangshan Formation.
GeoJSON
Fossils
The formation yields few fossils, with poorly-preserved conchostracans being found occasionally. Abundant spore and pollen fossils have been found only in the drilling cores from the basin of northern Jiangsu (Wu Qiqie and others, 1986).
Age
Depositional setting
The formation belongs to fluvial and lacustrine deposits.
Additional Information