江西岩背火山-侵入杂岩的微量元素协变关系及其岩浆房成分分带形成机制的探讨

以根据岩背斑岩锡矿区火山－侵入杂的微量元素Ｓｒ，Ｒｂ，Ｅｒ，Ｈｆ，Ｎｂ等协变关系，探讨了岩浆房成分分带的形成机理，认为初始岩浆的形成主要是经过两次聚集熔融作用（第一次熔出酸性岩浆，第二次熔出中酸性岩浆）。酸性岩浆未喷邮地表的部分在中溶部位经过平衡结晶作用（非理想），使Ｆ，Ｈ２Ｏ和成矿元素明显集中于晚期岩浆中。

COVARIANCE PLOTS OF TRACE ELEMENTS AND DISCUSSION ON A COMPOSITIONAL ZONATION OF MAGMA CHAMBERS FOR YANBEI VOLCANICINTRUSIVE COMPLEX IN JIANGXI PROVINCE

Taking the volvcanic-intrusive complex of Yanei Porphyry type tin depositarea as an example,according to the covariance plots of Sr, R. Zr,Hf,Nb in six different coordinates,the mechanisms of compositional zonation in magma chamber shave been discussed.The results suggest that the magma melts for first and second cycles both were formed by the colleectionla melting processes(acidic for first cycle;intermediate-acidic for second). A part of acidic magma for first cycle. which was not extruded onto the surface, might be crystallized in equilibrium state (non-ideal)at depth.leading to the enrichment in F, H2O and oreforming element. such as Sn, Nb.Ta ect. in the residual melt.