粤北扶溪岩体成因及时代:来自矿物化学、岩石地球化学及LA-ICP-MS锆石U-Pb年龄证据

发布时间：2018-05-01 21:35

本文选题：花岗闪长岩 + 矿物化学　；参考：《地质科技情报》2017年06期

【摘要】：分析了粤北扶溪地区花岗闪长岩角闪石、黑云母矿物化学组成,全岩岩石地球化学及LA-ICP-MS锆石U-Pb年龄。结果显示,花岗闪长岩中角闪石属镁角闪石,黑云母属镁质黑云母。岩石硅含量较高,w(SiO_2)为63.86%~66.19%;富碱,w(K_2O)为4.07%~4.71%,w(Na_2O)在2.42%~2.76%;铝质量分数中等,w(Al_2O_3)为14.27%~15.02%。稀土元素总量w(ΣREE)为183.22×10~(-6)~283.31×10~(-6),稀土元素配分模式右倾,中等强度负Eu异常(0.62~0.80),富集Rb、K、Th、Sr、Pb、Nd等大离子亲石元素,亏损Th、U、Zr、Hf、Nb、Ta、Ti等高场强元素。LA-ICP-MS锆石U-Pb年龄为(440.7±3.3)Ma(MSWD=2.4,n=18)。上述分析结果表明花岗闪长岩为I型花岗岩,是早志留世岩浆活动产物,岩浆主要来源于地壳物质的部分熔融,在温度777~802℃、压力316~442 MPa和氧逸度约lgf(O_2)=-14条件下侵位结晶。
[Abstract]:The chemical composition of hornblende, biotite, rock geochemistry and LA-ICP-MS zircon U-Pb age of granodiorite in Fuxi area, northern Guangdong Province, are analyzed. The results show that hornblende belongs to magnesium hornblende and biotite belongs to magnesia biotite in granodiorite. The higher content of silicon in rocks is 63.86% and 66.19; the ratio of alkali-rich wk / k _ 2O is 4.07 / 4.71 / W ~ + / Na _ 2O = 2.42 / 762; the middle mass fraction of Al / Al _ 2O _ 2O _ 3 is 14.2715.02 / 0 / 2, respectively, and the ratio is 14.2715.020.The content of Na _ 2O is 14.2715.02.The content of Na _ 2O is 14.2715.02in medium aluminum content. The total amount of rare earth elements w (危 REE) is 183.22 脳 10 ~ (10) ~ (-6) = 283.31 脳 10 ~ (-1) ~ (-6) ~ (-1), the REE distribution pattern is right tilted, the negative EU anomaly is 0.62 ~ 0.80 ~ (g), the enrichment of large ion lithophile elements, such as RbHZ _ (K) _ (T _ (+) ~ (?) Sr ~ (1) ~ (1) Pb _ (1) ND, etc., and the depletion of high field strength elements (such as Th ~ (Zr-HfH) ~ (+) NB ~ (+) TaTi) .LA-ICP-MS zircon U-Pb age is (440.7 卤3.3) MaMSWD2.4N ~ (18) N ~ (18). The results show that the granodiorite is I-type granite, which is the product of early Silurian magmatic activity. The magma is mainly derived from partial melting of crustal material, and is emplacement crystallization under the conditions of temperature 777C, pressure 316442 MPa and oxygen fugacity about lgf(O_2)=-14.
【作者单位】：中国地质调查局武汉地质调查中心;中国地质调查局花岗岩成岩成矿地质研究中心;东华理工大学;广东省核工业地质局291大队;
【基金】：国家重点研发计划“深地资源勘查开采”重点专项(2016YFC0600205) 中国地质调查局地质调查二级项目(DD20160134;121201009000150007)
【分类号】：P588.12

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