Jiehejie Fm

The type section is located at Fanjiaxia, south of Jiehe Street, about 40 km east by south of Zhen’an, Shaanxi. It was named by Shaanxi Team of Regional Geological Survey in 1966 during mapping the “Shaangxian Geological Map (the scale is 1:200000)”, and was published by “the Regional Stratigraphic Scale of Northwest China” (the shaanxi Province facsimile) in 1983.

Limestone. It is composed of gray to dark-gray thin- to medium-bedded, occasionally thick-bedded, micrite limestone and micrite, intercalated with black calcareous slate, siliceous slate and a few cherts in both the upper and lower parts. At Fanjiaxia in Zhen’an and at Shichuan in Zhangxian, the middle part is comprised by calcareous turbidite beds. This formation is 175 to 382 m thick.

Fossils are dominated by conodonts and foraminifera; mega fossil are rare, but trace fossils of deep-water facies are abundant. Conodonts Siphonodella sulioniodus, Pseudopolygnathus sp., etc. At Laohugou, Daping, Zhen’an, abundant Conodonts, Siphonodella duplicata, S. coopei, S. cf. isosticha, etc., have been collected, and Siphonodella crenulcata and Scaliognathus anchoralis have also been found regionally. At Tietonggou of Zhen’an, there are Brachiopods Eochoristites sp. and Fusella sp., and Corals Caninophyllum sp., Amygdalophyllum sp., etc. In the lower part of the Fanjiaxia section, it yields conodonts Palmatolepis g. gracilis, Pa. g. sigmodalis; from the upper part of the section at Zhaoyan in Jonê County of Gansu Province and from that at Hetaoba in Fengxian of Shaanxi Province, foraminifera of Eotubertina reitlingerae-Earlandia minor assemblage and conodonts of Gnathodus semiglaber-Scaliognathus anchoralis assemblage have been reported.

It is interpreted as a basinal facies.

The Xiongjiashan Fm at Xiongjiashan of Wafangba, Fengxian County is similar to this formation in lithology, and contains the above-mentioned conodont fossils, so that it should be the westward extension of the formation.