准噶尔盆地东缘华力西期中酸性侵入岩地球化学特征及其铀源供应能力  

Geochemical characteristics of Hersinian middle-acidic intrusion and its uranium supply capability as basin provenance at the eastern margin of Junggar basin

作　　者：倪仕琪 叶发旺[2] 黄波 赵洋 占美炎 NI Shiqi;YE Fawang;HUANG Bo;ZHAO Yang;ZHAN Meiyan(CNNC Overseas Limited,Beijing 100013,China;National Key Laboratory of Remote Sensing Information and Image Analysis Technology Beijing Research Institute of Uranium Geology,Beijing 100029,China;Xinjiang Zhundong Energy Investment(Group)Co.,Ltd,Changji,Xinjiang 831800,China;China Metallurgical Technology Achievement Transformation Co.,Ltd,Beijing 100080,China)

机构地区：[1]中核海外有限公司,北京100013 [2]核工业北京地质研究院遥感信息与图像分析技术国家级重点实验室,北京100029 [3]新疆准东能源投资(集团)有限公司,新疆昌吉831800 [4]中国冶金科技成果转化有限公司,北京100080

出　　处：《世界核地质科学》2024年第3期496-507,共12页World Nuclear Geoscience

基　　金：核能开发项目(编号:[2021]88)资助。

摘　　要：为研究准噶尔盆地东缘华力西期中酸性侵入岩对铀矿的物源供应能力,对本区具一定规模的中酸性侵入岩体进行综合研究,选择了有代表性的12个岩体开展了主、微量元素和稀土元素分析,发现本区花岗岩、花岗闪长岩及二长岩等岩体SiO_(2)含量介于65.69%~77.66%之间,(N_(2)O+K_(2)O)含量介于6.61%~9.39%之间,Al_(2)O_(3)含量介于9.72%~16.60%之间,TFe含量介于0.11%~4.00%之间,CaO含量介于0.20%~3.70%之间,MgO含量介于0.07%~1.43%之间,相对富集Rb、Th和K等大离子亲石元素及Zr、Hf等高场强元素,亏损Ba、Sr及Nb、Ta等元素,稀土元素总量介于100.47×10^(-6)~309.12×10^(-6)之间,LaN/YbN=2.38~11.48,LREE/HREE=3.09~9.77,Eu负异常,老鸦泉岩体为代表的大部分花岗岩体古铀含量介于4.02×10^(-6)~14.66×10^(-6)之间,高于地壳花岗岩的平均值(3.5×10^(-6)),w(Th)/w(U)>4.2,风化过程中发生了铀流失,铀迁移量可达0.08×10^(-6)~8.11×10^(-6)。认为准噶尔盆地东缘华力西期中酸性侵入岩多形成于后碰撞伸展阶段的火山岛弧环境,岩浆演化从钙碱性到碱性连续分异,呈高钾钙碱性-碱性过铝质花岗岩特征,岩浆主要来源于地壳,并受到地幔物质混染。提出本区花岗岩具有两种不同含铀性特征,一种属于富钍富铀花岗岩,古铀迁移量高,可为准噶尔盆地东缘卡姆斯特、加波萨尔和将军庙等地区铀成矿作用提供较好的铀源;另一种富钍贫铀,古铀迁移量低,作为铀源贡献不大。To analyze uranium supply capability of Hersinian middle-acidic intrusive rocks at the eastern margin of Junggar basin,after comprehensive study,this paper selected 12 plutons from the middle-acidic plutons in this region to analyze major,trace and rare earth elements.The results show that granite,granodiorite and monzonite in this region contain 65.69%~77.66%SiO2,6.61%~9.39%(N_(2)O+K_(2)O),9.72%~16.60%Al_(2)O_(3),0.11%~4.00%TFe,0.20%~3.70%CaO and 0.07%~1.43%MgO,rich in LILE(such as Rb,Th and K)and HFE(Zr,Hf)and poor in Ba,Sr and Nb-Ta,and the total REE is(100.47~309.12)×10^(-6) with LaN/YbN of 2.38~11.48,LREE/HREE of 3.09~9.77 and is depleted in Eu.The calculated Paleo-uranium content of most plutons is 4.02×10^(-6)~14.66×10^(-6),higher than the average uranium content(3.5×10^(-6))in crustal granite,and the w(Th)/w(U)is over 4.2,indicating that there was uranium migration during weathering process and migrated uranium was in range of 0.08×10^(-6)~8.11×10^(-6).It is believed that middle-acidic intrusion at the eastern margin of Junggar basin mainly formed in volcanic arc environments at post-collisional extension stage.The magma evolved continuously from calcalkalic to alkalic and appeared as high-K calcalkalic to alkalic pera-alluminium granites.The magma was mainly from crust and suffered from mixture of mantle materials.It is concluded that there are two kinds of granite with different uranium features in this region.One is Th and U fertile granite with high migration of paleo-uranium,which probably provided abundant uranium for the uranium mineralization in Karmst,Jabosar and Jiangjunmiao districts at the eastern margin of Junggar basin;the other kind is Th-rich but U-poor granite which is low in uranium migration and made little contribution to uranium mineralization.

关 键 词：中酸性侵入岩 地球化学 铀源 准噶尔盆地 

分 类 号：P598[天文地球—地球化学]