摘要
Yanshanian volcanic rocks are well developed in Southern Jiangxi-Northern Guangdong Provinces. They can be subdivided into three volcanic rock series: the upper, the middle, and the lower volcanic rock series. The zircon SHRIMP U-Pb dating results show that the apparent ages of 15 zircon crystals range from 410 Ma to 473 Ma, with a weighted average of (443.6±5.4) Ma, which represents the emplacement age of the porphyroclastic lava. According to the international stratigraphic chart, the porphyroclastic lava in the Houkou caldera came into being in the Late Ordovician to Early Silurian time, belonging to a volcanic activity during the late Caledonian period.