| 南秦岭志留系铅锌矿床中硅质岩岩石学及地球化学 |
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| 引用本文：.2005.Petrology and geochemistry of siliceous rocks in Silurian lead-zinc deposits of southern Qinling region[J].Mineral Deposits,24(5):490~500 |
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| 基金项目:中国地质调查局重点科技项目(200313000063)和教育部优秀青年教师资助计划项目 |
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| 中文摘要:南秦岭泥盆系内产出的众多矿床中含有层纹条带状硅质岩_硅质板岩，对其成因的研究有助于查明矿床成因和确定区域找矿方向。研究表明，硅质岩化学成分纯净，SiO2含量多在90%以上。硅质岩中大部分微量元素含量低于地壳克拉克值，但富集Zn、Pb、As、Sb、Ag；硅质岩的Fe_Mn_(Cu+Ni+Co)×10图解表明硅质岩具热水沉积性质。硅质岩与矿石两者的稀土元素特点相似，具有ΣREE低（44.52×10-6）、轻重稀土分异较明显（LREE/HREE=6.51）、北美页岩标准化配分曲线呈平缓趋势、铈负异常不明显(δCe值为0.97)和铕正异常明显(δEu值为1.42)的特点；硅质岩的δ30Si为-0.5‰～0.0‰，δ18O为17.8‰～19.9‰，硅、氧同位素组成及形成温度(84～101℃)也暗示它为海底热水沉积成因。 |
| 中文关键词:岩石学 地球化学 硅质岩 热水沉积 志留系 南秦岭 |
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| Petrology and geochemistry of siliceous rocks in Silurian lead-zinc deposits of southern Qinling region |
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| Abstract:The southern Qinling region is one of the important continental ore_forming belts in China. The survey and study of the Devonian base metal sulfide deposits in this region have made remarkable progress, as evidenced by the discovery of quite a few important Zn_Pb mineralization zones in Silurian strata of Xunyang basin within southern Qinling region. Laminated and banded siliceous rocks are widely distributed in the ore_bearing rocks, with their thickness ranging from n mm to 10 cm. These siliceous rocks are chemically very pure, and their SiO2 contents exceed 89%. The contents of trace elements vary considerably, and most of them are lower than their clarke values in the earth's crust. Nevertheless, the siliceous rocks are remarkably enriched in such trace elements as Zn, Pb, As, Sb and Ag. In the Fe_Mn_(Cu+Ni+Co)×10 triangle diagrams, all samples in the study area fall in the hydrothermal_sedimentary field. The siliceous rocks are characterized by low total REE contents (the average content being 44.52×10-6), and the average LREE/HREE value is 6.51. The North American shale normalized REE patterns of siliceous rocks are flat with no negative Ce anomaly and obvious positive Eu anomaly. δ30Si and δ18O values of the siliceous rocks range from 0.0‰ to -0.5‰ and from 17.8‰ to 19.9‰ respectively, and the formation temperatures (84～101℃) of these rocks are higher than those of normal sedimentary rocks. All these characteristics show that the siliceous rocks are mainly products of hydrothermal sedimentation. |
| keywords:petrology, geochemistry, siliceous rocks, hydrothermal sedimentation, Silurian, southern Qinling region |
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