诸广山岩体黄峰岭地区产铀花岗岩的岩浆液态不混溶成因  

Liquid immiscibility for U-bearing granites of Huangfengling area, in the middle of Zhuguangshan pluton, southern China

作　　者：邹明亮 方适宜 徐浩[2] 黄宏业 刘鑫扬 向庭富 

机构地区：[1]核工业230研究所,长沙410007 [2]核工业北京地质研究院,北京100029 [3]中国核工业地质局,北京100013

出　　处：《地质科学》2016年第3期850-871,共22页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国核工业地质局项目（编号：201456,2014105）资助.致谢野外工作中得到了核工业七一九矿部陶万才高级工程师、卢亮工程师的热心帮助,两位匿名审稿专家对本文提出了富有建设性意见,使笔者受益匪浅,在此一并致以诚挚谢意.

摘　　要：对华南诸广山岩体黄峰岭地区花岗岩开展了锆石U—Pb年代学、矿物学及岩石地球化学研究，提出产铀岩的成因与富氟花岗岩浆液态不混溶作用有关。将黄峰岭地区花岗岩划分为5类，LA—ICP—MS锆石U—Pb定年结果表明，“红化”似伟晶花岗岩成岩年龄为225．4±1．7Ma，与之共生的“红化”细粒黑云母花岗岩成岩年龄为222．9±2．7Ma和226．9±2．7Ma，表明两者形成时代相近且晚于印支期花岗岩岩基成岩年龄（235．4±1．1Ma）。通过镜下鉴定、长石单矿物x射线粉晶衍射以及热力学计算，认为黄峰岭地区钾、钠长石主要形成于成岩期，隶属于最大微斜长石及低钠长石系列，与晚期钠交代形成的长石存在差异。元素地球化学分析表明，不同类型花岗岩呈现出si—AI、K—Na分离，Nb—Ta、Zr—Hf等元素对分异现象，稀土元素配分模式表现出突变性、共轭性，ZREE-（La／Yb）。和La．La／Sm演化方向呈分离特征。区内晚期Li-F花岗斑岩脉及多处萤石矿床（点）证实大量氟元素的存在。上述特征综合分析表明：黄峰岭地区产铀花岗岩成岩期存在富氟花岗岩浆液态不混溶作用，且处于其中的中一低阶段，形成的富硅酸盐和贫硅酸盐系统导致了产铀的“红化”似伟晶花岗岩与细粒黑云母花岗岩的空间共生、地球化学共轭等特征，且铀主要富集于岩浆液态不混溶体系形成的花岗岩中。Huangfengling area is located in middle of Zhuguangshan pluton, Nanling large igneous province in southern China. Researches on the LA-ICP-MS zircon U-Pb geochronology, mineralogy and petrogeochemistry of granites in this area have been conducted, proposing that the origin of uranium-bearing granites were related with the liquid immiscibility of fluorine-rich magma. Based on the divide of granites in Huangfengling area, LA-ICP-MS zircon U-Pb dating results showed that age of reddening pegmatoid granite was 225.4＋_1.7 Ma, while the reddening fine-grained biotite granite associately were 222.9 ± 2.7 Ma and 226.9± 2.7 Ma respectively, indicating that granites of both types were formed synchronization and later than the Indosinian granite （235.4± 1.1 Ma）. The results of the microscopic identification, X-ray powder diffraction and thermodynamic calculation of feldspar showed that the potassium and sodium feldspar which belonging to the maximum microcline and low albite series, have been formed in the diagenetic stage mainly, which were different with the terminal heat-treated albite. Analysis of element geochemical showed that Si-AI and K-Na separation, Nb-Ta, Zr-Hf and other elements couple differentiation, the rare earth elements distribution pattern were mutagenicity and conjugation and ZREE-（La/Yb）N with La-La/Sm owned the separation characteristics of evolution direction in different types of granites. Moreover, the presence of late stage Li-F granite porphyry vein associated with many fluorite deposits （or prospecting points）around Huangfengling area implied that there have been massive fluorine element. Comprehensive analysis of these characteristics indicates that, the origin of uranium-bearing granites was related to the fluorine-rich liquid immiscibility in diagenetic stage of Huangfengling area, and belonged to the medium-low stage in this system, which have formed the rich and poor silicate systems, resulted the phenomenon of reddening pegmatite granite associated with fine granite uranium

关 键 词：诸广山岩体 产铀花岗岩 岩浆液态不混溶 成矿作用 

分 类 号：P588.121[天文地球—岩石学] P619.14[天文地球—地质学]