福建紫金山矿床初始成矿流体来源及性质——来自稀土和微量元素的证据

成矿流体来源及性质是确定岩浆热液矿床找矿方向、建立找矿预测模型的重要依据。通过对紫金山铜金矿区内主要岩体岩石、典型矿石的对比分析,发现矿石与花岗闪长斑岩稀土元素特征相似,且花岗闪长斑岩岩体的形成年龄与成矿时间极为接近,可以为成矿流体提供足够的热量,因此推断该矿床的成矿流体最初来源于深部隐伏花岗闪长斑岩岩体分异的岩浆热液。矿石中富集Th、Nb、Ta、Zr、Hf等高场强元素和轻稀土元素,Hf/Sm值和Nb/La值都大于1,表明成矿流体具有F含量多于Cl的性质。结合前人大量的研究资料,建立了二庙沟—中寮剖面找矿预测模型。

A discussion on the source and nature of initial ore-forming fluids of the Zijinshan deposit in Fujian province: Evidence from REE and trace elements

The source and nature of ore-forming fluids constitute an important basis for determining prospecting orientation and establishing the model of prospecting prediction for magmatic hydrothermal deposits. The authors have found that ores and granodiorite-porphyry are similar to each other in REE characteristics, as shown by a comparative analysis of major plutons and typical ores, and that the formation age of granodiorite-porphyry pluton is so closed to metallogenic time, thus the pluton could provide enough heat for the ore-forming fluids. It is thus inferred that magmatic hydrothermal fluids were derived from deep concealed granodiorite-porphyry pluton, which served as the original source of ore-forming fluids. The high field strength elements (HFSE) (Th, Nb, Ta, Zr, Hf, etc.) of ores are relatively high with enrichment of LREE, and HFSE/LREE ratios (Hf/Sm, Nb/La) are higher than 1, suggesting that F is richer than Cl in ore-forming fluids. On such a basis and in combination with a lot of previous researches, the authors have established a model for ore-prospecting prognosis along Ermiaogou-Zhongliao section.