High-precision laser ⁴⁰Ar/³⁹Ar age of volcanic rocks in Longhai-Zhangpu area, Fujian Province

Cenozoic volcanic rock is wildly distributed in Longhai-Zhangpu area in the southeast of Fujian Province. The basalts are part of Fotan Group. Previous research was mainly focused on the geochemical characteristics, the formation, and the evolution of the volcanic rock in this area. However, the study of geochronology of these rocks remains very insufficient. The eruption periods of basalt is still based on the K-Ar dating conducted in the 1980s and 1990s, or inferred from the ages of the pollen assemblage features of plants in the underlying strata. In order to obtain high quality data, the authors applied the laser ⁴⁰Ar/³⁹Ar dating method to four samples of volcanic rocks taken from Longhai-Zhangpu area. The results indicate that there was an eruption of Longhai-Zhangpu volcanoes around 10.1~14.8Ma. In other words, the time interval was in the Middle-Late period of the Miocene.