摘要
Eastern China is made of a number of large and small continental fragments throughout late Paleozoic and Mesozoic time,and is still the best natural laboratory for examining kinematic models of continent tectonics.The paleoelevation history of eastern China provides direct insight into the tectonic processes in China.Here we present basalt-vesicularity based estimates of the paleoaltimetry of the early Cretaceous basalts in northern East China,which indicate that the studied basalt units were at an elevation of more than 4 kilometers in late Mesozoic.Two vesicular basaltic rocks have been collected form bottom to top along the lava flow outcrop in eastern Inner Mongolia.After the digital precessing to the sample cross-sections,and taking advantage of the stereological conversion method to acquire the bubble size distributions,paleoelevation estimate was calculated for East China in the early Cretaceous.The results show that the elevation has been near 4700±750 m when the lava flows was cooling,implying that there were highland regions in the northern part of the East China Plateau during the early Cretaceous.Combined with other geological evidence,we conclude that there was a high plateau with elevation near 5000 m above sea level in Eastern China during the late Mesozoic.This ancient high plateau in eastern China was most likely formed by the collision of the north and south China blocks.
Eastern China is made of a number of large and small continental fragments throughout late Paleozoic and Mesozoic time,and is still the best natural laboratory for examining kinematic models of continent tectonics.The paleoelevation history of eastern China provides direct insight into the tectonic processes in China.Here we present basalt-vesicularity based estimates of the paleoaltimetry of the early Cretaceous basalts in northern East China,which indicate that the studied basalt units were at an elevation of more than 4 kilometers in late Mesozoic.Two vesicular basaltic rocks have been collected form bottom to top along the lava flow outcrop in eastern Inner Mongolia.After the digital precessing to the sample cross-sections,and taking advantage of the stereological conversion method to acquire the bubble size distributions,paleoelevation estimate was calculated for East China in the early Cretaceous.The results show that the elevation has been near 4700±750 m when the lava flows was cooling,implying that there were highland regions in the northern part of the East China Plateau during the early Cretaceous.Combined with other geological evidence,we conclude that there was a high plateau with elevation near 5000 m above sea level in Eastern China during the late Mesozoic.This ancient high plateau in eastern China was most likely formed by the collision of the north and south China blocks.
基金
supported by the National Natural Science Foundation of China(40972084)
the US National Science Foundation(EAR-0911331)
