【摘要】 南秦岭晚古生代凤县—太白盆地是在扬子地台北缘早古生代被动大陆边缘发展起来的具裂陷性质的盆地,处在秦岭微板块当中,在盆地内既产有八卦庙超大型金矿也产有八方山—二里河大型铅锌矿床,是铅锌与金矿床共生/共存的一个典型地区。两种矿床在地质背景、产出层位和成矿特征等方面具有某些关联,铅锌矿层产在中泥盆统古道岭组灰岩与上泥盆统星红铺组变泥质岩过渡层位的铁白云石—钠长石—硅质热水沉积岩系中,金矿体位于上泥盆统星红铺组底部,由含石英细脉多期变形的蚀变钠长石、铁白云石粉砂岩等热水沉积岩系构成。硅同位素组成反映金矿床中存在两类不同来源的硅,一类是钠长石岩和顺层石英细脉的硅同位素组成(δ30Si=-0.40‰～-0.32‰),与铅锌含矿层中硅质岩的硅同位素组成相似,硅质与热水沉积作用相关,另一类是金矿体中的穿层石英脉,其硅同位素反映硅来自晚期岩浆流体;铅锌矿床硫化物中硫同位素(δ34S=6.03‰～16.88‰)反映硫主要来自海底热水沉积,形成于盆地早期开放体系;金矿石中硫化物硫同位素组成(δ34S=4.10‰～15.40‰)反映硫主要为地层硫,形成于盆地晚期半封闭—封闭体系;铅同位素组成反映盆地内由西坝岩体泥盆系地层铅锌矿石金矿石铅同位素演化有幔源成分减少,壳源成分增加的趋势;氢、氧同位素数据揭示出铅锌矿成矿流体中的水来自于大气降水,金矿则具多源性,包括岩浆水、大气降水和变质水。研究认为泥盆纪海底热水沉积作用形成了铅锌矿层的主体,也使金(银、铜)在热水沉积岩系中明显富集,而中生代造山过程中的构造—流体作用使金矿体定位。金与铅锌的共生/共存关系,受控于这种成矿地质过程及流体化学、物理化学演化。金与铅锌的这种时空关系可作为已知矿床深部勘查和外围找矿的依据。更多还原

【Abstract】 Lower Paleozoic Fengxian—Taibai basin in the southern Qinling Mountains was the fault basin which developed from Late Paleozoic passive continental margin, belonging to the northern margin of the Yangtze platform. The basin is located at the Qinling micro tectonic plate. In this basin there exist the Baguamiao super large gold deposit and Bafangshan—Erlihe large-scale lead—zinc deposit. It is the typical area where lead—zinc and gold deposits paragenesis(coexist). There are some relationships between two kinds of deposits in geological background, position and mineralizing characteristics, etc. The lead—zinc ore-bodies lie in ankerite—albite—silicon hydrothermal sediment rock series between calcareous rocks of the Middle Devonian Gudaoling Formation and metapelite of the Upper Devonian Xinghongpu Formation. The gold ore bodies are located at the bottom of the Upper Devonian Xinghongpu Fm., which is composed of hydrothermal sediment rock series, including alteration albite, ankerite siltstone that suffer multiple phases of deformation, and quartz stringer vein.The silicon isotopic data reflect there are two types of different origin silicon in gold ore bodies. One is albitite and bedding-parallel quartz stringer veins (δ30Si=-0.40 ‰ ~-0.32 ‰), which is similar to the silicalite of lead—zinc ore-bearing beds. The silicon origin correlates with hydrothermal sediment. The other is transecting quartz vein in the gold ore bodies. The data reflect that silicon comes from magmatic fluid of the later period; The sulfur isotope data of sulfide in the lead—zinc deposit (δ34S=6.03~16.88 ‰) reflect that the sulfur mainly comes from the hydrothermal sediment and forms in the open system of early time basin; The sulfur isotope contents of sulfide in gold ore (δ34S=4.10~15.40‰) reflect that the sulfur are mainly from the strata and form at half seal—closed system of later period basin; The data of lead isotopic reflect the lead isotope evolution tendency of mantle material reducing and crust material increasing from the Xiba graniteDevonian strata lead—zinc ores gold ores; the hydrogen and oxygen isotope data indicate that the water of mineralization fluid in lead—zinc ore-bodies comes from meteoric water but the gold ore-bodies are charaterized by multiple sourced water, including magma water, meteoric water and metamorphic water. It is concluded that the Devonian sea-bottom hydrothermal sediment formed the main part of lead—zinc ore-beds and enriched obviously gold, silver and copper; then Mesozoic structure-fluid processes caused the gold ore-bodies allocation. The relationship of paragenesis between gold and lead—zinc is controlled by mineralization process, fluid chemistry and the physical—chemistry evolution. This temporal—spacial relationship of gold and lead—zinc can be regarded as the base for deep exploration and peripheral prospecting.更多还原