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对黄铁矿开展Rb-Sr同位素测年可以获得直接的成矿年龄,但目前成功率较低.找出影响黄铁矿Rb-Sr同位素体系的地质因素是改进和应用该方法的关键之一.采用超低本底Rb-Sr同位素测定方法,对取自豫西祁雨沟金矿4号角砾岩筒中的黄铁矿开展测年研究.结果表明,结晶好、裂隙不发育的单颗粒黄铁矿给出了Rb-Sr等时线年龄(126±11)Ma,代表了主成矿期的时代.碎裂的或含细粒集合体的黄铁矿未能给出合理的等时线年龄.晶体形貌及包裹体研究揭示Rb和Sr可能主要赋存于黄铁矿中的黑云母、钾长石和绢云母包裹体中,碎裂状黄铁矿在后期流体作用下容易使Rb-Sr同位素体系受到扰动,不利于开展Rb-Sr定年研究.
Rb-Sr isotope dating of pyrite can lead to direct metallogenic age, but the success rate is low at present. Finding out the geological factors that affect the Rb-Sr isotope system of pyrite is one of the keys to improve and apply this method The dating of pyrite in No.4 breccia from Qiyuogou gold deposit in western Henan was studied by using ultra-low background Rb-Sr isotope method.The results show that the single grain of yellow The iron ore gives an Rb-Sr isochron age of (126 ± 11) Ma, representing the age of the main mineralization. The fractured or fine-grained pyrite fails to give a reasonable isochron Age.Research on crystal morphology and inclusions revealed that Rb and Sr may occur mainly in biotite, potash feldspar and sericite inclusions in pyrite, and the fragmented pyrite could easily make Rb- Sr isotope system perturbed, is not conducive to carrying out Rb-Sr dating.