Hulushan Fm

East end of South Qinling tectonic region. The type section is located at Hulushan of Zaqu, about 15 km southwest of Neixiang County, Henan Province. It was named by the Southern Team of Henan Regional Geological Survey of Beijing Geological Collage in 1961, and Zhang Haiqing formally quoted it in 1987.

Sandstone. Lower part, 140 m thick, is composed of grayish-white thick-bedded medium- to fine-grained quartzose sandstone, interbedded with lithoclastic sandstone and grayish-yellow silty claystone.

Middle part, 40 m thick, consists of grayish-brown thick-bedded clayey siltstone intercalated with white thick-bedded medium- to fine-grained quartzose sandstone.

Upper part, 40-136 m thick, is represented by grayish-white thick-bedded quartzose sandstone intercalated with grayish-brown iron-bearing clayey siltstone, shale, lithoclastic sandstone, iron-bearing quartzose sandstone and hematite beds.

The thickness of this formation in the areas of Xichuan and Neixiang counties, Henan Province is stable, commonly between 230-290 m.

The lower part of this formation yields abundant brachiopods represented by the Yunnanella acme zone; and in the area of Yongqingshan of Neixiang County, the upper part yields plant fossils of the Sublepidodendron mirabilis-Lepidodendropsis hermeri assemblage zone.