**1. Introduction**

High purity quartz is a high-tech strategic mineral resource which is scarce in the world and in China,and the quartz sandstone of littoral facies is a potential highpurity deposit [1]. It is the raw material of high-grade quartz products and the material basis of high-end products in silicon industry. It can be widely used in photovoltaic electronic information electric light source and optical communication industry. It plays an important role in strategic emerging industries such as new materials and new energy [2]. High purity quartz sandstone is a characteristic mineral in Wumeng mountain area, mainly distributed in northeast Yunnan province, which is the pillar mineral for zhaotong Government to build "Yunnan Silicon Valley" [3]. The current domestic production of high purity quartz sandstone strata in fluvial facies (Xiaodian in Suqian city, Sidaoliangzi in Inner Mongolia, Hewan in Lanzhou city), lacustrine facies (Dengjiatun in Shuangliao city, Yamenying and Zhangwutai in Tongliao city, Songfeng in Jiangxi), less littoral facies is found and always mainly loose quartz sand (Dongfang city, Beihai city, Dongshan city), it's low purity and impurity. The large-scale production of high-purity quartz sandstone produced in northeast Yunnan is restricted by the lag of mineral resources assessment and sedimentary facies research. Therefore, it's the strategic demand to carry out the potential evaluation of high-purity quartz ore in northeast Yunnan and expand its resource stock to support "Yunnan Silicon Valley". The Middle Devonian Suotoushan Formation distribute extensive in Yiliang area, northeast Yunnan, and it's an important potential area of high purity quartz sandstone deposit [4]. Previous studies based on small scale and limited outcrop sequence stratigraphy considered that the sedimentary facies of middle Devonian in northeast Yunnan is barrier coast facies [5], and more detailed sedimentary facies analysis has not been carried out systematically. Therefore, the author carried out a systematic study on the sedimentary characteristics of the Member 1 of Suotoushan Formation, collected 7 samples for grain size analysis and 22 samples for chemical analysis (**Figure 1**), and discussed the sedimentary facies characteristics of the first member of Suotoushan Formation and the genetic mechanism of the high purity quartz sandstone in northeast Yunnan.

The study area is located in the Kang-Dian fault depression belt at the western edge of the South China block, with kang-dian uplift in the west and Upper Yangtze uplift in the north, forming a southward opening bay, known as Zhaotong-Weining Depression (called Zhaotong Bay in this paper) [6]. In the late Middle Devonian, the study area is a littoral shallow sea clastic sedimentary area, mainly composed of quartz sand with high maturity in the littoral zone, distributed in a ring band on the east side of the Kang-Dian uplift and the southwest side of the Upper Yangtze uplift. Due to the influence of the Middle Devonian Haikou movement, small uplift is seen in the interior of the bay (**Figure 1**) [6]. Created by Xian Si-yuan in 1974 its mountain group name in Suotoushan of Qingmen in zhaotong city, the Middle Devonian strata group of Qingmen which is the shelf sea sedimentary contact the Late-Middle Devonian on Hongyapo group of tidal flat shelf sea sedimentary contact, main rock is fine-grained quartz sandstone, pure texture, well sorting and roundness. The lower and upper as a pure quartz sandstone, the middle part is sandstone with siltstone and mudstone [7]. The Suotoushan Formation in the area can be roughly divided into three members. The Member 1 and Member 3 of Suotoushan Formation are mainly quartz sandstone. The Member 2 of Suotoushan Formation contains more siltstone and mudstone. The quartz sandstone in the first member of Yutoushan Formation has the purest texture and is the host layer of high purity quartz sandstone in the study area.

*Sedimentary Characteristics of the Member 1 of the Middle Devonian Suotoushan Formation… DOI: http://dx.doi.org/10.5772/intechopen.103826*

### **Figure 1.**

*Devonian tectonic setting, paleogeographic framework, brief geological map of Northeastern Yunnan and sampling position (after reference [5]).*
