In addition to syenite ring dykes and multiple alkaline granite stocks, the sub-volcanic Houshihushan alkaline ring complex near Shanhaiguan, Qinhuangdao City, contains cone-sheets of two types: a majority filled with granite porphyry and a minority filled with quartz syenite porphyry. Many cone sheets show evidence of multiple magma intrusion events. Some granite porphyry sheets’ multiple chilled margins display magmatic roll structures indicating that turbulent magma flowed up the fractures. In one upward-closing cone-sheet K-feldspar phenoc...
