过铝质岩浆-热液演化体系中磷的地球化学行为  

Geochemical behavior of phosphorus in the peraluminous magmatic-hydrothermal system

作　　者：唐勇[1] 张辉[1] 刘丛强[1] 饶冰[2] 

机构地区：[1]中国科学院地球化学研究所地球深部物质与流体作用地球化学研究室 [2]南京大学成矿作用国家重点实验室,江苏南京210093

出　　处：《岩石矿物学杂志》2008年第2期127-134,共8页Acta Petrologica et Mineralogica

基　　金：国家重点基础研究发展计划资助项目(2007CB411303);国家自然科学基金资助项目(40273030)

摘　　要：泥质岩部分熔融产生的过铝质岩浆中的P2O5含量受控于源区磷灰石含量、部分熔融程度和岩浆中磷灰石的溶解度。过铝质岩浆中的Ca、REE以及Y的活度低,阻碍了磷灰石、独居石以及磷钇矿等的结晶,碱性长石成为过铝质岩浆中P的主要寄主矿物,直到岩浆演化晚期,Li的活度增大,P才与Li形成磷铝锂石-羟磷铝锂石。进入以晶体、熔体和流体相共存为特征的岩浆-热液过渡阶段体系后,P的地球化学行为主要受流体/熔体相分配的制约,P优先进入到熔体相,不太可能形成富P的流体。在热液阶段,长石晶体在Al-Si有序化过程中释放的结构P与流体介质所携带的Ca离子形成次生磷灰石。在热液蚀变过程中所形成的富P流体,很可能是某些Sn、W、Mn和U热液矿床的主要载体。During the anatexis of metapelite, the phosphorus content of initial magma is mainly controlled by the apatite contents of the source, the melting degree and the solubility of apatite in the melt. Strong depletion of Ca, ∑REE and Y in the peraluminous magma hinders the crystallization of phosphate minerals such as apatite, xenotime and monazite. The alkali feldspars crystallizing from the P-rich peraluminous magmatic system constitute the main phosphorus reservoirs. As P has strong affinity to Li, an amblygonite-montebrasite assemblage occurs at the last stage of magmatic evolution. In magmatic-hydrothermal transition stage, phosphorus is in favor of the melt and can hardly form P-rich fluid. During the hydrothermal alteration, a lot of secondary apatites were formed as the P was released by Al-Si ordering of alkali feldspar and Ca was provided by external hy- drothermal fluid. Some of Sn, W, Mn and U, whose mineralizations were hosted in hydrothermal veins, were probably transported as M-P complex in P-fluid resulting from hydrothermal alteration.

关 键 词：磷 过铝质岩浆 岩浆-热液体系 地球化学行为 

分 类 号：P595[天文地球—地球化学]