闽西下白垩统坂头组锆石U-Pb年龄及地层对比

通过闽西地区永安盆地与崇安盆地下白垩统坂头组凝灰岩夹层中的岩浆锆石定年研究以及古生物研究,首次获得2个盆地坂头组底部开始沉积的准确年龄,分别为（144±2）和（116±2）Ma。根据它们与上覆地层关系来看,2个盆地坂头组顶部年龄基本等时约为100 Ma。因此,崇安盆地坂头组仅相当于永安盆地吉山剖面上段。在与临区地层对比...

The Zircon U-Pb Dating of the Lower Cretaceous Bantou Formation in Western Fujian and Stratigraphic Correlation

We Present the first report of the beginning ages of the Bantou Formation of Yong′an and Chong′an Basins in western Fujian, (144±2)Ma and (116±2)Ma, respectively, by combining the U-Pb LA-ICPMS dating of zircons from the tuffs interbeds and paleontological research, whereas the top of two Bantou Formation sections is basically isochronous at about 100Ma, according to the unconformable contact with the Upper Cretaceous fluvial and alluvial pebbly sandstone. Therefore, the Chong′an Xiamei section is comparative to the upper part of the Yong′an Jishan section. We propose the Bantou Formation in the Yong′an Basin be correlated to the Jiande Group and Guantou Formation in the western Zhejiang province, while the Bantou Formation in Chong′an Basin is only correlated to the Guantou Formation. Furthermore，the detailed research on the probability density and the peaks distribution of the zircon ages demonstrated that the rift time of the Yong′an and Chong′an Basin were different (157±3)Ma and （127±2）Ma BP, respectively, and it is the mainly cause for the different beginning ages of the Bantou Formation. The analysis of the two typical Bantou Formation section illustrated that although the evolution of the basins, the strata structure and sequence are the same under the dominant extending settings since the late Mesozoic, the rift time of basin in different regions is not isochronous. Consequently, the successions which look similar to each other are not deposited coeval very well. Great importance should be attached to the future research of the early cretaceous volcanic-sedimentary system of southeast China.