京津地区铁岭组,景儿峪组海绿石^40Ar—39Ar年龄

The Ages of Glauconites from Tieling and Jingeryu Formations,Beijing-Tianjin Area

利用海绿石４０Ａｒ－３９Ａｒ年龄校正公式，通过测量海绿石中的可膨胀层含量ｎ以及中子活化过程中３９Ａｒ的丢失率，求出海绿石的年龄。经测定，京津地区铁岭组、景儿峪组海绿石中可膨胀层含量为５％～６％，中子活化中３９Ａｒ丢失率为１７％～１９％。由校正后的海绿石年龄推测出铁岭组年龄界限范围是１０７０±１０Ｍａ～１１７５±１０Ｍａ，景儿峪组为８１０±１０Ｍａ～９００±１０Ｍａ。

The glauconites from Tieling Fm.and Jingeryu Fm. Beijing-Tianjin Area,contain 5%～6% expandable layer, and the lost rate of 39Ar during neutron irradiation is between 17% and 19%.From these data and the corrected formula for,40Ar-39Ar dating of glauconites deduced by the authors in other paper,the ages of the glauconites from these two Formations are calculated. The corrected ages of the glauconites from Tieling Fm. are between 10821±13Ma and 1171±11Ma and those from Jingeryu Fm. are between 816.1±8.9Ma and 880.0±8.5Ma,from which the authors suggest that the age range of Tieling Fm. is 1070±10Ma to 1175±10Ma and that of Jingeryu Fm. is 810±10Ma to 900±10Ma.