摘要
The Qinling Mountains in central China are the joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. The ages of the metamorphic strata in this area were measured by U-Pb, Sm-Nd, Rb-Sr, 40Ar/39Ar and other methods. Isotopic data show that the metamorphic rocks, except the Yudongzi gneisses in the South Qinling belt, which were formed in Archean, are all Proterozoic products and that the Qinling area underwent three episodes of strong geological events since 1 600 Ma. The first episode is the Jinning period, about 1 000 Ma, when in North and South Qinling belts severe changes took place and the rocks were subjected to strong metamorphism, accompanied by crust partial melting and volcanism. The second episode is the Caledonia - early Variscan period, about 400 Ma, generally considered as an important tectonic-thermal event, when the Qinling area was again subjected to strong metamorphism, accompanied by acid magma intrusions and eruptions. The third episode is another tectonic-thermal event in the late Variscan-lndosinian period, about 280-200 Ma, when the Rb-Sr isotopic system was reset and the intensity became stronger and stronger from the North to the South Qinling belt.
The Qinling Mountains in central China are the joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. The ages of the metamorphic strata in this area were measured by U-Pb, Sm-Nd, Rb-Sr, 40Ar/39Ar and other methods. Isotopic data show that the metamorphic rocks, except the Yudongzi gneisses in the South Qinling belt, which were formed in Archean, are all Proterozoic products and that the Qinling area underwent three episodes of strong geological events since 1 600 Ma. The first episode is the Jinning period, about 1 000 Ma, when in North and South Qinling belts severe changes took place and the rocks were subjected to strong metamorphism, accompanied by crust partial melting and volcanism. The second episode is the Caledonia - early Variscan period, about 400 Ma, generally considered as an important tectonic-thermal event, when the Qinling area was again subjected to strong metamorphism, accompanied by
基金
Project supported by the National Natural Science Foundation of China.
