Dajian Fm

Xueshan range, north Taiwan. The naming section is located at Dajian Village ~45 km east of Taichung County, Taiwan. In the monograph Regional Geology of Taiwan Province (1992) the definition of “Dajian sandstone” is used but it is renamed the Dajian Formation. Originally named the “Dajian sandstone” by Chen Zhaoxia in 1977.

Primarily white or light gray, thick-bedded or massive, medium- to coarse-grained quartzite-like sandstone, with thin- to thick-bedded slate or metamorphic shale, shale sometimes containing slight carbon. Three parts may be distinguished: Lower part, 650 m thick, consists chiefly of fine- to coarse-grained quartzite, green chlorite sandstone, siltstone and small amount of slate; Middle part, 1300 m thick, is made up of coarse-grained to massive quartzite with well-developed cross bedding; Upper part, 750 m thick, is marked by thick-bedded, medium- to coarse-grained quartzite-like sandstone, with small amount of shale or carbonaceous shale. The thickness is ~2700 m thick.

In this formation now only small quantities of fossils have been found, e.g. the bivalve Corbicula baronensis, the gastropod Turritella sp. and the foraminifera Nummulites sp. and Discocyclina sp.