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为了解由早期(伟晶、巨晶)斑状二长花岗岩、中期(细粒)花岗岩和晚期花岗(斑)岩脉组成的马鞍山杂岩体的成因,采用SHRIMP和LA-ICP-MS锆石U-Pb法厘定其侵入时代,年龄显示伟晶斑状二长花岗岩为132.2±1.6Ma,巨晶斑状二长花岗岩为127.7±1.2Ma,细粒花岗岩为128.3±1.1Ma,花岗斑岩脉为127.4±1.8Ma.岩石地球化学研究结果表明岩体从早到晚具有从钾玄岩系列向高钾钙碱系列演变特征,分异演化程度逐渐变高;斑状二长花岗岩具有高REE含量,轻重稀土分异较为明显,具较强负铕异常和弱右倾的配分曲线特征,富集K、Th、U、Rb等元素,弱亏损Ba、Sr、P、Nb、Ta、Ti等元素;细粒花岗岩及花岗(斑)岩脉具有较低REE含量,轻重稀土分异不明显,具强负铕异常和“V”型配分曲线特征,富集K、Th、U、Rb等元素,强亏损Ba、Sr、P、Nb、Ti等元素.马鞍山岩体为浙西北-皖南地区早白垩世俯冲造山后陆内拉张作用环境下下地壳部分熔融的同源岩浆侵位结晶分异作用形成的产物,具有高分异I型花岗岩的特征.
In order to understand the genesis of the Ma’anshan complex formed by the early (Peijing and Giantjing) porphyritic monzonitic granite, middle-stage (granite) granite and late granodioritic dikes, SHRIMP and LA-ICP-MS zircon U-Pb method to determine the age of its invasion, the age shows that the pegmatite porphyritic monzonitic granite 132.2 ± 1.6Ma, macrophyllite monzonitic granite 127.7 ± 1.2Ma, fine granite 128.3 ± 1.1Ma, granite porphyry veins 127.4 ± 1.8Ma. The results of lithogeochemistry show that the rock mass has evolved from the basaltic series to the high-K calc-alkaline series from early to late, and the degree of differentiation evolution gradually becomes higher. The porphyritic monzogranite has high REE content, The variation of rare earth is obvious with strong negative europium anomaly and weaker right demarcation curve. It enriches elements such as K, Th, U, Rb and weakly depletes Ba, Sr, P, Nb, Ta, Ti and other elements. The REE content of granite and granodiorite dikes is low, and there is no significant difference between light and heavy rare earths, with strong negative Eu anomaly and “V ” type distribution curve, enriching K, Th, U, Rb and other elements, Strong loss of Ba, Sr, P, Nb, Ti and other elements.Maanshan rock for the northwestern Zhejiang - Wannan area after the Early Cretaceous subduction orogeny inland tension Emplacement homologous portion of the lower crust throughout the molten fractional crystallization products formed, having a high iso-I-type granites features.