Restrictions on gold mineralization by zircon oxygen fugacity from the Paleozoic-Mesozoic magmatic rocks in the Zhangjiakou district,northern margin of the North China Craton
The Zhangjiakou district,located at the northern margin of the North China Craton,is an important goldfield in China.Gold deposits in this district are commonly enriched in tellurium,and gold mineralization is closely associated with magmatic rocks.In this paper,we provide zircon oxygen fugacity of the Paleozoic-Mesozoic magmatic rocks from this district,with the aim to evaluate their mineralization potential and to constrain their gold and tellurium sources and genesis.The results of different zircon oxybarometers,including Ce4+/Ce3+,Ce-U-Ti,Ce/Nd and EuN/EuN*,give a relative consistent trend of magmatic oxygen fugacity.Combined with geological characteristics and other oxybarometers,we think the Ce-U-Ti oxybarometer is more reliable.The order of the oxygen fugacity values for magmatic rocks from the Zhangjiakou district is Qingyanggou granite(average ΔFMQ=+4.4),Zhangjiakou Formation rhyolite(average ΔFMQ=+3.2),Shuiquangou syenite(average ΔFMQ=+2.6),pegmatite vein(average ΔFMQ=+2.5),Shangshiuquan granite(average ΔFMQ=+1.5),Xiangshuigou granite(average ΔFMQ=+1.4),Xiangshan granodiorite(average ΔFMQ=+1.2).Medium-high oxygen fugacity(around sulfide-sulfate transition)is efficient for migration and enrichment of Au and Te.The Shuiquangou syenite,pegmatite vein and Qingyanggou granite exhibit similar oxygen fugacity levels to the Dongping and Dabaiyang gold deposits.The exsolution magmatic fluids associated with these rocks possess elevated oxygen fugacity,a strong capacity to transport Au,Te and other elements,and a high potential for ore formation.Zircon trace element compositions from the Shuiquangou alkaline rocks indicates several characteristics of fertility magmatic suite,including EuN/EuN*＞0.3,10000 ×(EuN/EuN*)/Y＞1,(Ce/Nd)/Y＞0.01,Dy/Yb＜0.3,and a positive correlation between(EuN/EuN*)/Y and(Ce/Nd)/Y.The oxygen fugacity and trace element composition of zircons reveal that the Shangshuiquan alkaline rocks possess a favorable potential for Au-Te mineralization,whereas the mineralization potential of the Shangshuiquan granite is limited.The tellurium-rich gold deposits in the Zhangjiakou district have close genetic relationships with the Shuiquangou alkaline rocks.
Gold mineralizationZircon oxybarometerPaleozoic-MesozoicZhangjiakou districtNorth China Craton
万方数据
维普
