Yaolinghe Fm

Southeast Shaanxi. The Yaolinghe Fm was named by the Party of Qinling Regional Geological Surveying, Ministry of Geology and Mineral Resources in 1959. The naming section is in Yaolinghe area, Shangnan County, Shaanxi Province.

Synonym: （耀岭河组）

The original definition of the formation is a suite of metamorphosed eruptive rocks-green schist rocks, which is subdivided into two parts. Lower part consists of chlorite ortho-schist and chlorite albite ortho-schist, albite hornblendite; chlorite ortho-schist and green schist interbedded with sericite albite schist. Upper part is composed of green schist-like actinolite epidote schist, albite chlorite schist with marble, carbonaceous schist with minor conglomerate. The formation in the naming section is 500 m thick.

However, later study shows that the formation is a suite of unstable interbeddings of marine metamorphosed volcanic rocks and clastic rocks. The volcanic rocks are mainly spilite with spilitic breccia, ignimbrite and sericite schist with clastic rocks (conglomerate, sandstone or quartzite, magnetite quartzite) and minor marble or limestone. The volcanic and clastic rocks change considerably in lithology and thickness along the strike. In the Shangnan and Zhaochuan area, it consists mainly of green schist with marble and magnetite quartzite and is over 1828 m thick. Going westward, in Zhougcun of Shanyang, it consists of schistose crystal tuff, 500 m thick. In Shanyang area, it is gray green, purple red intermediate-basic volcanic rocks with rhyolite and tuff, over 300 m thick. In Xixia, Henan Province, it consists mainly of spilite with spilitic lava breccia, tuff, hematite sericite quartz schist and volcanic breccia, 1500-2600 m thick. In Niushan, Ankang area, it consists of spilite and intermediate basic volcaniclastic rocks, over 713 m thick. In Ziyang-Pingli area, it consists of metamorphosed spilite and intermediate basic to intermediate-acidic volcaniclastic rocks, 775 m thick. There are commonly unstable interbeds of quartzite and conglomerate, with the conglomerate considered by some to be of glacial origin (Liu Hongyun, 1991, Wang Shouqiong, 1990). Therefore, the thickness of the variable formation ranges from 300 to 2600 m.