北淮阳东段佛子岭群变质岩地球化学特征及其地质意义  

Geochemical characteristics and geological implications for the metamorphic rocks of Foziling Group in Eastern of North Huaiyang Tectonic Belt

作　　者：柴广路 李双应[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,安徽合肥230009

出　　处：《地学前缘》2016年第4期29-45,共17页Earth Science Frontiers

基　　金：中国地质调查局项目(12120113094300);安徽省公益性地质工作项目(2014-g-9);国家自然科学基金项目(41172097)

摘　　要：北淮阳地区的佛子岭群是一套经受了多次变形、变质作用的低级变质岩系。佛子岭群主量元素平均含量为SiO_275.42%、Al_2O_38.13%、MgO 1.52%、Fe_2O_33.23%、Na_2O 1.61%、K_2O 1.67%、TiO_2 0.41%;特征微量元素Th、U、Hf、Sc、Zr、Y平均含量分别为8.49×10^(-6)、1.47×10^(-6)、4.85×10^(-6)、170.66×10^(-6)、193.69×10^(-6)、18.97×10^(-6);Th/U、La/Y、Th/Sc、La/Sc比值分别为4.92、3.56、1.51、1.38;∑REE含量125.3×10^(-6),δEu=0.67,轻稀土富集,La/Yb=14.99,(La/Yb)N=10.11。下部的祥云寨组主要为一套变质石英砂岩,原岩为砂岩和杂砂岩,构造环境以被动大陆边缘为主,物源以石英岩沉积岩物源区为主,并显示了亲扬子陆块的特征。而诸佛庵组和潘家岭组为一套云母石英片岩、石英云母片岩和二云片岩,原岩为杂砂岩、亚岩屑砂岩、岩屑砂岩及页岩,构造背景为大陆岛弧和活动大陆边缘,物源区主要为石英岩沉积岩物源区和长英质火成岩物源区,并显示了亲华北陆块的特征,表明佛子岭群经历了由扬子北缘被动大陆边缘向华北南缘活动大陆边缘的构造转化。Foziling group of North Huaiyang is a set of lower metamorphic rocks which had undergone multiple deformations and metamorphism.The average contents of Foziling Group are SiO_275.42%,Al2O38.13%,MgO 1.52%,Fe_2O_3 3.23%,Na_2O 1.61%,K_2O 1.67%,TiO_2 0.41%;apart of characteristic trace elements like Th,U,Hf,Sc,Zr,Y have average of 8.49×10^-6,1.47×10^-6,4.85×10^-6,170.66×10^-6,193.69×10^-6 and 18.97×10^-6,respectively;and the ratio of Th/U,La/Y,Th/Sc,La/Sc are respectively4.92,3.56,1.51 and 1.38;the average of∑REE is 125.3×10-6,δEu is 0.67,light REE enrichment,La/Yb is 14.99and（La/Yb）Nis 10.11.The lower part of Foziling group which named Xiangyunzhai Formation is a set of metamorphic quartz sandstone whose protolith are sandstone and greywacke rock,and it has a tectonic setting of passive continental margin and a provenance of quartzite and sedimentary rocks which indicates the Yangtze（-phile）geochemical features. However,the upper part of Foziling Group metamorphic rocks including Zhufoan Formation and Panjialing Formation mainly consists of a set of quartz-mica schist,micaquartz schist,mica schist and minor quartz quartzite and its protolith are greywacke,sublitharenite,litharenite and shales.Its tectonic setting is continental island arc and active continental margin and its provenance are mainly quartzite sedimentary rocks and felsic igneous provenance.That shows the characteristics of North China Plate-affinitive.The above information suggests that Foziling Group has undergone the tectonic transformation from the passive continental margin of northern Yangtze to the active continental margin of southern margin of North China.

关 键 词：地球化学 原岩恢复 构造背景 佛子岭群 北淮阳 

分 类 号：P588.3[天文地球—岩石学]