LA-ICP-MS zircon U-Pb geochronology studies were carried out on the Late Mesozoic volcanic rocks from the Chaohu-Lujiang segment of the Tan-Lu fault zone. The eruption ages acquired by 6 samples ranged from 125 Ma to 93 Ma, namely, from late Early Cretaceous to the earliest Late Cretaceous, and the volcanic eruption elongated for about 32 Ma. The terminal time of the eruption in the area was later compared with neighbouring regions such as the Luzong Basin, the North Dabie orogen and the North Huaiyang belt, which indicated a longer extension along the Tan-Lu fault zone, and a more intensive lithospheric thinning. The age of 93 Ma might be the youngest magmatic record as known on residual enriched mantle of the North China Craton. Zircon saturation thermometry and the low content of MgO, Mg# didn’t support the model of lower crust delamination, while crust-mantle interaction might be a reasonable interpretation for magma formation. Magma sources varied from mantle to crust and then to mantle again, which hinted that intense asthenosphere upwelling beneath the fault zone caused lithospheric mantle partial melting (125 Ma ago), then incessant lithospheric thinning conduced heat flow increasing followed by crustal partial melting indicated by occurrence of rhyolite (120 Ma ago), and the participating of asthenosphere mass in the terminal magma (93 Ma ago) being a reason for its mantle source.
Xie Chenglong,Zhu Guang,Niu Manlan et al. Zircon U-Pb geochronology of the Late Mesozoic volcanic rocks from the Chaohu-Lujiang segment of the Tan-Lu fault zone[J]. Chinese Journal of Geology, 2008, (2): 294-308.