粤东北南雄群碎屑锆石矿物学、稀土元素地球化学特征及物源分析  

Detrital Zircon Mineralogy,Rare Earth Element Geochemistry and Provenance Analysis of Nanxiong Group in Northeast Guangdong

作　　者：闵壮 吴德海 潘家永[1,3] 黄广文[1] 何定洋[4] 唐金露 MIN Zhuang;WU De-hai;PAN Jia-yong;HUANG Guang-wen;HE Ding-yang;TANG Jin-lu(East China University of Technology,Nanchang 330013,China;School of Resources,Environment and Jewelry,Jiangxi College of Applied Technology,Ganzhou 341000,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;292 Brigade of Guangdong Province Nuclear Industry Geological Bureau,Heyuan 517000,China)

机构地区：[1]东华理工大学,江西南昌330013 [2]江西应用技术职业学院资源环境与珠宝学院,江西赣州341000 [3]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [4]广东省核工业地质局二九二大队,广东河源517000

出　　处：《稀土》2021年第2期30-40,共11页Chinese Rare Earths

基　　金：国家重点研发计划项目(2017YFC0602600);核资源与环境国家重点实验室开放基金项目(2020NRE03)。

摘　　要：锆石中的稀土元素(REE)对于反映锆石的形成环境、成因类型具有重要意义。以粤东北南雄群含矿碎屑岩为研究对象,利用碎屑组分分析、重矿物分析和锆石稀土元素分析等手段,探讨了南雄群沉积岩岩石学特征及碎屑岩物质来源,结果表明,南雄群以较低结构成熟度和成分成熟度的岩屑长石砂岩、长石岩屑砂岩为主,碎屑物来自近源的石英再旋回造山带构造背景;阴极发光图像指示碎屑锆石以岩浆成因为主;碎屑锆石的稀土元素含量变化范围较大,(La/Yb)_N值介于0~0.23,LREE/HREE值介于0.003~0.741,其中轻、重稀土分馏明显且重稀土元素相对富集,进一步指示锆石大部分来自岩浆成因,伴有少量复杂成因变质锆石存在。本文根据不同时期形成的锆石稀土元素特征,将锆石分为吕梁期、晋宁期、加里东期、印支期和燕山期五组,各组锆石稀土元素配分曲线存在些许差异,综合认为南雄群碎屑物质主要来源于长田盆地北缘和西缘出露的侵入体。The rare earth elements(REE)in zircons are of great significance in reflecting the formation environment and genetic types of zircons.This paper takes the clastic rocks of the Nanxiong Group in northeastern Guangdong as the research object,using clastic component analysis,heavy mineral analysis and zircon rare-earth element analysis to explore the characteristics of sedimentary rocks and the source of clastic rocks in the Nanxiong Group.The results show that the Nanxiong group is mainly composed of lithic arkose and feldspathic lithic sandstone with low structural maturity and compositional maturity.The detritus comes from the proximal quartz recirculating orogenic belt.The Cathodo Luminescence(CL)image indicates that the detrital zircon is mainly of magmatic origin,and the content of rare earth elements varies widely.The(LA/Yb)_N value ranges from 0 to 0.23,and LREE/HREE value ranges from 0.003 to 0.74.The obvious fractionation of light and heavy rare earth elements and the relative enrichment of heavy rare earth elements further indicate that most of the zircons come from magmatic origin,accompanied by a small amount of metamorphic zircons of complex origin.According to the REE characteristics of zircons formed in different periods,the zircons can be divided into five groups:Luliang,Jinning,Caledonian,Indosinian and Yanshanian.There are some differences in REE distribution curves of zircons in each group.It is considered that the detrital materials of Nanxiong group are mainly from the intrusions exposed in the northern and western margin of Changtian basin.

关 键 词：碎屑锆石 稀土元素 物质来源 构造背景 粤东北 

分 类 号：P588.[天文地球—岩石学]