摘要
本文对江西赣南横市地区基性岩墙进行了年代学、岩石学和地球化学研究,主量元素特征和微量元素分析结果显示,基性岩墙为拉斑玄武岩系列和钙碱性系列,属于富钠基性岩类;Ti O2含量较高,平均含量1%,属于钛较高的基性岩类;A/NCK均小于1,属于准铝质基性岩类,具幔源型岩浆特征。基性岩墙LA-ICP-MS锆石U-Pb定年法测年结果为422.8±1.8 Ma和421.7±2.2 Ma,时代属于晚志留世,表明该基性岩墙是加里东期褶皱造山运动期后拉张(伸展)作用的产物。该地区不仅出露了加里东期同造山期和后造山期两类酸性花岗岩岩体,而且在该地区还同时出现加里东期的酸性岩类及基性岩类,大致反映了该地区从挤压型酸性岩浆侵位逐渐转换为拉张环境的基性岩浆侵位构造过程。
LA-ICP-MS Zircon U-Pb Ages,Geochemical Characteristics of the Silurian Basic Dykes in the Hengshi Area,Southern Jiangxi,and Their Geological Significances,and the diagenetic models and source characteristics are preliminarily discussed. The geochemical Characteristics indicate that the mafic dykes are pertain to the tholeiite series and calc alkaline series,and also belong to the sodium rich rock type. Especialy the Ti O2 values are in the average of 1%,attributes to the basic rocks enrich of titanium. A / CNK values are less than 1%,shows that it belongs to the meta-aluminous basic rocks,and displaying it s mantle derived magmatic characteristic.LA-ICP-MS U-Pb isotopic dating of zircons separated from the mafic dykes yields average206 Pb /238 U ages of( 422. 8± 1. 8) Ma and( 421. 7 ± 2. 2) Ma,respectively,indicate that the mafic dykes belong to the Late Silurian,suggesting that the mafic dykes are later Caledonian orogenesis period in the tension( stretch) settings. At the same time,exposing two kind of acidic granite of the Caledonian orogenic and post orogenic period in this area,Which generally reflects this area has experienced the construction process from the extrusion type acidic magmatic emplacement gradually converted to tension mafic magma emplacement.
出处
《地质论评》
CAS
CSCD
北大核心
2015年第6期1417-1428,共12页
Geological Review
基金
中国地质调查局地质调查项目(编号1212011120812)的成果
