江西九龙嶂和相山火山—侵入杂岩岩石地球化学的对比研究

Comparative Research of Lithogeochemistry for Jiulongzhang and Xiangshan Volcano Intrusive Complexes

九龙嶂和相山火山—侵入杂岩是中国华南地区与铀矿有关的中生代流纹英安质火山—侵入杂岩。相山火山—侵入杂岩是华南地区最大的火山岩型铀矿赋矿围岩, 其主体岩石为流纹质碎斑熔岩, 浅成—超浅成侵入岩有英安斑岩、花岗斑岩等; 九龙嶂火山—侵入杂岩的铀资源潜力尚待评价, 主体岩石为流纹质熔结凝灰岩, 浅成—超浅成侵入岩有英安斑岩、石英二长斑岩等。两地区的火山—侵入杂岩的岩石化学成分及其变化特点极为相近, 微量元素蛛网图和稀土配分型式也基本一致, 它们具有相似的岩浆过程和统一的活动陆缘构造背景; 同时, 从早期火山岩浆活动到晚期浅成—超浅成岩浆侵入活动, 其w(SiO2 )和w(Rb) /w(Sr)的值降低, 而w(MgO)以及w(K) /w(Rb)、w(Ba) /w(Rb)和w(LREE) /w(HREE)的值增高, 晚期浅成—超浅成侵入岩与早期火山岩没有直接的分异演化关系。

Jiulongzhang and Xiangshan volcano intrusive complexes are the Mesozoic rhyodacitic volcano intrusive complexes associated with uranium ores in southern China Xiangshan volcano intrusive complex is the wall rock of the biggest volcanic rock uranium ore deposit in China, and the main body is rhyolitic porphyroclastic lava, accompanied by hypabyssal or ultra hypabyssal intrusive rocks such as dacite porphyry and granite porphyry Jiulongzhang volcano intrusive complexes are dominantly rhyolitic welded tuff, accompanied by dacite porphyry and quartz monzonite porphyry, and so on, and the uranium resources are being assessed The comparative studies of lithogeochemistry for the volcano intrusive complexes both from Jiulongzhang and from Xiangshan reveal that the chemical compositions of the volcano intrusive complexes in the two areas are very close , and the trace element spidergrams and REE patterns basically coincide with each other It is also shown that the two volcano intrusive complexes have the same source features and the active continental margin tectonic settings At the same time, it is found that, from early volcanic magma activities to later intrusive magma activities, the content of SiO 2 and the Rb/Sr ratio decreased, on the contrary, the content of MgO and the ratios of K/Rb, Ba/Rb and LREE/HREE increased It is shown that the hypabyssal or ultra hypabyssal intrusives are not the products of the volcanic magmatic differentiation