巴音戈壁盆地苏红图组时代归属研究

笔者根据玄武岩钾-氩同位素年龄,从盆地沉积演化和充填特征等方面讨论了巴音戈壁盆地苏红图组的构成特点,认为苏红图组沉积贯穿于早白垩世湖盆地演化的全过程,但盆地内苏红图组的形成具有不等时性。盆地西部苏红图组形成较早,为代表盆地形成之初的一套地层岩性组合,其中玄武岩夹层的钾-氩同位素年龄为141～146Ma,归属早白垩世早期;盆地东部苏红图组形成较晚,为代表盆地萎缩阶段的一套地层岩性组合,其中玄武岩夹层的钾-氩同位素年龄为108～109Ma,时代归属早白垩世中晚期。盆地内中生代火山活动具有自西向东的发生过程。苏红图组时间跨度达30Ma以上,远远超出通常一个地层组的时间间隔,建议对其拆分。

Discussion on the chronology of Suhongtu formation in Bayingebi basin

This paper discussed the characteristic of Suhongtu formation in Bayingebi basin based on the K-Ar isotopic age of basalt rock and the deposition character of the basin evolvement,it was found that Suhongtu formation had been developed from the beginning to the end of the basin in the early Cretaceous,but Suhongtu formation was asynchronous,Suhongtu formation in the west part was formed earlier which is characterized by a set of sediments with the interacted basalt of the 141-146 Ma K-Ar age and belong to lower Cretaceous,while Suhongtu formation in the east part was formed later which is characterized by a set of shrinking sediments with the interacted basalt of the 108-109 Ma K-Ar age and belongs to upper Cretaceous.Volcanic action in the basin was developed from west to east. The age span of Suhongtu formation reaches 30 Ma which is much longer than that of a normal formation.So it is suggested that Suhongtu formation should be divided.