广西平天山岩浆热液成矿系统分带及成矿模式综述

A Review on Zonation and Metallogenic Model of the Magmatic-Hydrothermal Ore-Forming System in the Pingtian Mountain, Guangxi

摘要: 平天山–龙山矿田作为钦杭成矿带南段典型金多金属矿集区，远端金矿成因长期存在造山型与岩浆热液型争议，现有研究多聚焦单一矿床，缺乏成矿系统层面的整合分析。针对这一议题，本文在系统梳理矿床地质特征、流体包裹体及稳定同位素证据的基础上，对该区成矿系统的时空结构与动力学机制进行了综合评述。本研究确立了该区为受燕山期中酸性岩浆驱动的巨型岩浆热液成矿系统，在空间上呈现严格的向心式分带规律：内带(龙头山)发育斑岩–隐爆角砾岩型Au-Cu矿化，中带(砷矿沟)发育层状矽卡岩型Pb-Zn矿化，外带(六梅)发育受构造控制的微细浸染状Au-As矿化。成矿流体演化轨迹表明，内带的流体减压沸腾(相分离)与外带的流体混合/硫化作用是驱动差异化成矿的关键机制。本文建立了该区成矿系统的“套叠”演化模式，指出岩浆流体超压释放与区域构造剥蚀共同制约了矿床的定位，据此预测，内带岩体深部的斑岩型铜(钼)矿与外带主构造深部的隐伏高品位金矿是未来找矿突破的关键方向。

Abstract: The Pingtian Mountain-Longshan Mountain ore field, as a typical gold polymetallic concentration area in the southern segment of the Qinzhou-Hangzhou metallogenic belt, has long been debated regarding the genesis of distal gold deposits between orogenic-type and magmatic-hydrothermal type. Existing studies mostly focus on individual deposits and lack an integrated analysis at the ore-forming system scale. To address this issue, based on a systematic review of deposit geological characteristics, fluid inclusion and stable isotope evidence, this paper comprehensively evaluates the spatiotemporal structure and dynamic mechanisms of the ore-forming system in this area. This study establishes that the area represents a giant magmatic-hydrothermal ore-forming system driven by Yanshanian intermediate-acidic magmatism, exhibiting a strict concentric zoning pattern in space: the inner zone (Longtoushan) hosts porphyry and cryptoexplosive breccia-type Au-Cu mineralization, the intermediate zone (Shenkuanggou) hosts stratiform skarn-type Pb-Zn mineralization, and the outer zone (Liumei) hosts structurally controlled micro-disseminated Au-As mineralization. The evolution trajectory of ore-forming fluids indicates that fluid decompression boiling (phase separation) in the inner zone and fluid mixing/sulfidation in the outer zone are the key mechanisms driving differential mineralization. This paper establishes a “nested” evolution model for the ore-forming system in this area, pointing out that the overpressure release of magmatic fluids and regional tectonic denudation jointly constrain the localization of ore deposits. Accordingly, it is predicted that the deep porphyry Cu (Mo) deposit beneath the inner zone intrusion and the concealed high-grade gold deposit in the deep part of the main structure in the outer zone are key directions for future breakthrough in mineral exploration.