太行山南段平顺地区矽卡岩铁矿地质特征及成矿模式探讨

GEOLOGICAL CHARACTERISTICS AND METALLOGENIC MODEL OF SKARN IRON DEPOSITS IN PINGSHUN AREA,SOURTHERN TAIHANG MOUNTAINS

平顺地区矽卡岩型铁矿位于太行山南段山西省境内，主要产于燕山期中性侵入岩与中奥陶统碳酸盐岩地层接触带及其附近。矿化蚀变带明显，钠长石化是重要的找矿标志。矿化蚀变带特征和黄铁矿矿物（^206Pb／^204Pb=17．741～18．301，平均值17．993；^207Pb／^204Pb=15．433～15．551，平均值15．495）与早期侵入岩（^206Pb／^204Pb=17．859～18．474；^207Pb／^204Pb=15．429～15．431）以及晚期侵入岩（^206Pb／^204Pb=17．959～18．223，平均值18．088；^207Pb／^204Pb=15．434～15．566，平均值15．536）的Pb同位素组成均说明晚期闪长岩是主要的成矿母岩，但早期超基性-基性侵入岩通过被晚期中性侵入岩交代同化，大量铁质进入晚期中性岩浆之内，间接为铁矿体的形成提供了物质来源。晚期侵入体的岩浆热液不仅是成矿物质的载体，而且所产生的压应力和热能成为成矿流体运移的驱动力。在成矿过程分析的基础上，建立了本区矽卡岩型铁矿床的成矿模式。

The Pingshun skarn iron deposits in the southern Taihang Mountains of Shanxi Province mainly occurred along the contact zone between Yanshan intermediate rocks and Middle Ordovician carbonate rocks. The mineralization and alteration showed pronounced zoning with albitization being the important ore-hunting indicator. ^208 Pb/^204 Pb and ^207 Pb/^204 Pb ^206 pb/^204 Pb ratios of pyrite were in the ranges of 17. 741 - 18. 301 （average 17. 993） and 15. 433 - 15. 551 （average 15. 495） respectively. ^208Pb/^204Pb and ^207Pb/^204Pb ^206Pb/^204Pb ratios of early intrusive rocks samples were 17. 859- 18. 474, and 15. 429 - 15. 431 respectively, while later intrusive rocks samples were 17. 959-18. 223 （average 18. 088）,and 15. 434-15. 566 （average 15. 536）,respectively. Pb isotopic compositions of various kinds of samples from the deposit and characteristics of mineralization alteration zone implied that later intrusive rocks are main metallogenic mother rock,while the early ones were metasomaticed by the later ones. The later rocks related to ore deposits formed by 2;3 magmatic pulses,and the compressive stress and heat produced by hydrothermal solutions were dynamic forces for the migration of ore-forming materials. Based on the above analysis,an ore-forming model of skarn iron deposits in the area was proposed.