山东邹平王家庄铜矿含矿岩体地球化学及成因探讨

Geochemistry and genesis of the ore-bearing intrusions in the Wangjiazhuang copper deposit,Zouping,Shandong Province

王家庄铜矿床是山东省重要的铜金属产地之一．在野外地质工作基础上，通过岩石化学和同位素地球化学等方法，详细研究了与王家庄铜金矿床有关的石英二长岩，研究表明含矿岩体具有偏碱性，富钠和准铝质的特征；Rb、Ba、Sr等大离子亲石元素（LILE）和Th、U富集，Nb、Ta、Ti等高场强元素（HFSE）亏损；轻重稀土分异明显（La／Yb）N=23．09～29．93，未见Eu异常（8Eu=0．85～1．05）．全岩^205Pb／^204Pb介于18．5826～18．6675之间，均值为18．6197；^207Pb／^204Pb介于15．5850～15．6077之间，均值为15．5931^207Pb／^204Pb介于38．5749～38．6109之间，均值为38．5980；全岩δ^18O值变化于8．23‰～10．90‰之间，均值为9．40‰；铅、氧同位素组成表明成岩物质来自地壳深部或地幔，岩浆在上升过程中可能受到富^18O地壳物质的混染，具富放射性成因铅的特征（^207Pb／^204Pb〉18．00）．

The Wangjiazhuang copper deposit is one of the most important producing areas of copper in Shandong Province. Based on geological field work, we conducted systematical study on the petrochemistry and isotopic chemistry of the ore-bearing intrusion in order to discuss the genesis of the quartz monzonite, which is associated with the mineralization of Wangjiazhuang copper-gold deposit. The analysis results indicate that the intrusion belongs to metaluminous alkaline quartz monzonite characterized by high alkali （Na2O〉 K2O）. Rb, Ba, Sr, Th and U are enriched, while Nb, Ta and Ti are depleted. REE pattern shows a strong LREE enrichment with （La/Yb）N ratios from 23.09 to 29.93 and no clear Eu anomaly is observed as δEu values is from 0.85 to 1.05. The value of ^207Pb/^204 Pb ranges from 18. 582 6 to 18. 667 5 with an average value of 18. 619 7 ; ^207Pb/^204 Pb ranges froml5. 585 0 to 15. 607 7 with an average value of 15. 593 1 ; and ^207Pb/^204pb ranges from 38. 574 9 to 38. 610 9 with an average value of 38. 598 0. The value of δ^18 O ranges from 8.23%o to 10.90%0, and the average value is 9.40%o. Both lead and oxygen isotopes indicate that the magma was derived from mantle or lower crust, and some matter of the crust mixed into the magma during the intruding process, presenting the characteristics of radiogenic lead isotope as mentioned above.