海南岛白垩纪千家岩体岩石地球化学特征及其成矿作用分析

Petrochemical characteristics and metallogenic analysis of the Cretaceous Qianjia rockbodies in Hainan Island

呈环套式产出的千家岩体生成于晚白垩世地壳由伸展期往扩张裂解期的转化阶段,属于壳幔岩浆混合的产物,具有明显的成分演化和结构演化。从早至晚,地幔物质参与减少,而地壳组分贡献增大,岩石由中酸性向酸、碱性方向演化。主要成矿元素在不同岩石中的分异能力强,含量离散度高,与钼、银、铅、锌等元素成矿作用有着明显密切的关系。后期近南北向断裂的多次构造热液活动,加剧了成矿元素的分馏,控制了岩体内钼多金属矿的产出。与钼矿有密切关系的晚期花岗斑岩体R b/S r值为0.48,显示其成矿物质可能来源于地幔。

The Qianjia rockbodies which occurred in rings were formed in the transforming stage when the Late Cretaceous crust switched from extension stage to spreading-breakup stage, and is the outcome of mixture magma from mantal and crust with obvious component and strucure evolvement. From early to late, mantle material involved decreased, while crust material increased, and the rocks evolved from intermediateacid to acid and basic. The major ore-forming elements in different rocks, which differentiated mightily , whose content has a high dispersion degree, have a close relationship with the metallogeny affected by Mo, Ag, Pb, Zn and other elements. The late tectonic hydrothermal activities of the near SN trend fault has strengthened the fractionation of the ore-forming elements, and controlled the occurrence of the Mo polymetallic deposit in rockbodies. The Rb/Sr value of the late granite porphyry rockbodies that have a close relationship with the Mo deposit is 0. 48, which has shown the ore-forming matters may come from mantle.