摘要
吉林省中部磐石县境内烟筒山地区的红帘石硅质岩存在于古生代地层之中。地球化学研究发现,该硅质岩具有较低的SiO2(80%左右)和较高的Al2O3(10%左右),微量元素中V的含量也较低,稀土元素中不出现明显的Ce负异常,表明其形成于与陆源物质关系密切的大陆边缘环境。岩石的强烈变形和无层序特点暗示该区的古生代地层可能大多为构造混杂岩,不具备传统的地层划分和对比意义。矿物温压计算结果显示,该硅质岩经历了约430℃、大于6.0GPa的中压相系变质作用,不存在其他高压变质作用矿物,可能反映了本区为兴蒙造山带中古亚洲洋最后闭合的地点所在,并推测其最后闭合的时间应在古生代末—中生代初期。
Piemontite-bearing chert occurs in Paleozoic strata at Yantongshan,Panshi County,central Jilin Province.Geochemical study shows that this kind of chert is characterized by lower SiO 2 (～80%),higher Al 2 O 3 (～10%)and lower V without significant negative Ce anomaly,which suggests that it formed in a continental-margin environment closely related to terrestrial material.The intense deformation of the rocks and resulting destruction of the original sedimentary sequence indicate that most of the Paleozoic strata in this region might be tectonic mélange without any significance for the traditional stratigraphic division and correlation.The mineral p-T calculations show that the chert has undergone intermediate-pressure facies metamorphism with a temperature of ～430℃and a pressure of >0.6GPa and that no other high-pressure metamorphic minerals have been identified.This suggests that this area might be the site of the final clos-ing of the Paleo-Asian Ocean,and it is inferred that the final closing of the ocean may have taken place in the terminal Paleozoic to initial Mesozoic.
出处
《地质通报》
CAS
CSCD
北大核心
2003年第6期391-396,共6页
Geological Bulletin of China
基金
国土资源部"中国大陆三维岩石圈结构"专项计划
高校博士学科点专项基金(2000018707)项目资助
关键词
吉林省中部
红帘石硅质岩
古亚洲洋
central Jilin
piemontite-bearing chert
Paleo-Asian Ocean
