浙江洋滨斑岩锡矿成矿流体特征

在岩石地球化学、同位素地球化学的研究基础上，通过对浙江洋滨斑岩锡矿成矿流体的一系列研究．从流体角度探讨了洋滨斑岩锡矿的成矿机理。本区沸腾流体包裹体的形成压力约为25～40MPa，主要成矿深度约为0．76～1．22km，说明含矿岩浆是在浅成一超浅成环境下侵位的，由于压力突然降低及有少量大气降水混入，导致流体沸腾，加速矿质沉淀。流体包裹体中多种子矿物的发现及各相成分分析结果充分表明当时有多种不混溶流体被同时捕获，且不混溶的岩浆-流体富含成矿元素，进一步证实了洋滨斑岩锡矿属岩浆-大气降水混合型矿床，成矿物质主要来源于花岗斑岩。

Characteristics of ore_forming fluids in Yangbin porphyry tin deposit, Zhejiang Province

Based on petrological, geochemical and isotope geochemical studies, the authors made a detailed investigation into the ore-forming fluids in the Yangbin porphyry tin deposit. With the results obtained, this paper deals with the metallogenic mechanism from the angle of fluids. The pressure of boiling inclusions is about 25- 40 MPa, and the main ore-forming depth is 0.76-1.22 km or so. These data suggest that tin-bearing melts were emplaced in a hypabyssal or ultrahypabyssal environment, where the sudden reduction of the pressure and the mixing with small amounts of meteoric water led to the boiling of fluids and the acceleration of ore material precipitation. The existence of many daughter crystals in fluid inclusions and a compositional analysis of various phases indicate that varied kinds of immiscible fluids were trapped simultaneously, and the immiscible melts-fluids were enriched in ore-forming elements. It is thus concluded that the Yangbin porphyry tin deposit is of the melt-meteoric water mixing type, with the ore-forming materials derived from the granite porphyry.