The Geological map of the Dongkeng volcanic depression in Zhenghe County (adapted from data of Fujian Geology Survey Institute, 2016). (a) Pacific Rim Volcanic Eruption Belt I, China’s southeast coastal volcanic activity belt II. (b) Ningde City Ring Volcano Eruption Center III. (c) Dongkeng Volcanic Depression IV. (d) Drilling section of spherulitic rhyolite porphyry. (e) Volcano tectonic diagram cross section.