大别造山带核部桃园寨火山岩锆石U-Pb定年及其地质意义

应用U-Pb和二次离子探针(法国产SIMS 1270)U-Pb法对大别造山带核部桃园寨火山岩中的锆石进行了年龄测定,给出其形成年龄为136～129 Ma。这一研究表明,大别造山带核部存在晚侏罗世—早白垩世火山活动和火山盆地,也说明在这一时期,该区的构造环境与北淮阳地区相似。据现残存的火山地貌和标高,及相邻的北淮阳地区的中生代火山盆地及火山沉积物的厚度,推测其剥蚀深度约 3000 m。

U-Pb Zircon Dating and Its Geological Significance of the Taoyuanzhai Volcanic Rock, Central Dabie Organic Belt

Zircons from the Taoyuanzhai volcanic rock, central Dabie orogenic belt, Anhui Province, are dated using conventional and SIMS (1270) U-Pb methods. The eruption age is given at 129-136 Ma, suggesting a Late Jurassic-Cretaceous volcanic event, as well as a volcanic basin in the area. It is also suggested that the tectonic environment was probably similar to that of the North Huaiyang in the north. According to the residual vol-canic topology, the height above sea and comparison to the thickness of volcanic sediments of the adjacent North Huaiyang Mesozoic volcanic basin, the erosion is estimated at about 3000 m in depth.