辽西早白垩世火山岩喷发期次及同位素年代学研究

A Study on Early Cretaceous Volcanic Effusion Periods and Isotope Chronology in Western Liaoning

辽西彰武—黑山地区位于阜新—义县盆地以东,除第四系表土大面积覆盖外,露头区内最常见的就是火山岩系。而火山岩层位、喷发期次和时代的确定对辽西化石层、找煤、构造及沉积演化的研究都有着重要意义。本次工作是在系统收集了辽西地区中生代火山岩年龄的基础上,对阜新—义县盆地和彰武—黑山地区采集的11件火山岩样品进行了SHRIMP U-Pb同位素分析;系统收集了辽西地区中生代火山岩年龄,结合新测得的数据提出辽西地区的白垩世的火山活动分五次,活动时间分别为132±1Ma、126±1Ma、122±2Ma、115±2Ma和100±5Ma。基于统计学结果认为引起辽西地区乃至东北地区地壳减薄的起止年龄为132±1Ma至115±2Ma。

The Zhangwu-Heishan area is located to the east of Fuxin-Yixian Basin.Besides the large area covering of Quaternary soil,most commonly outcropped is volcanic rocks.The horizon and age of volcanic rock play an important role to understand fossil beds,structures and sedimentary evolution of western Liaoning as well as in coal seeking.In this work,11 volcanic rock samples were measured through SHRIMP U-Pb isotope analysis.Based on the original age data of Mesozoic volcanic rocks in western Liaoning,combined with new measured data,Cretaceous volcanic activities in western Liaoning can be divided into 5 stages,namely 132±1Ma,126±1Ma,122±2Ma,115±2Ma and 100±5Ma.Based on statistical result,this paper has concluded that the thinning time of the crust in western Liaoning even whole Northeast China is from 132±1Ma to 115±2Ma.