安徽安庆月山岩体锆石年代学和Hf同位素:岩石成因的指示  

ZIRCON CHRONOLOGY AND HF ISOTOPES OF THE YUESHAN INTRUSION IN ANQING,ANHUI:INDICATORS OF ROCK GENESIS

作　　者：王次松[1] 陈林杰[1] 简东川 方德[2] 谢建成[2] 

机构地区：[1]安徽省地质矿产勘查局321地质队,安徽铜陵244033 [2]合肥工业大学资源与环境工程学院,安徽合肥230009

出　　处：《安徽地质》2017年第1期11-17,38,共8页Geology of Anhui

基　　金：国家自然科学基金(编号:41373045)资助

摘　　要：安徽月山地区是我国铜金产地之一,成矿与岩浆作用关系密切。近年来,安庆月山中生代侵入岩的成因仍存在分歧。本次我们报道了安庆月山岩体新的锆石U-Pb年龄、锆石原位微量元素和Hf同位素数据。LA-ICP-MS锆石U-Pb定年结果表明月山闪长岩的形成年龄为138.2±1.7Ma(MSWD=0.61)。月山岩体具有典型的岩浆锆石特征:一致的重稀土富集、Ce正异常和弱Eu负异常的稀土配分模式,高Th/U比值和(Sm/La)N值,低La含量。锆石HHf(t)值为-10.0^-5.4(平均值-7.9),二阶段模式年龄(tDM2)为1530~1822Ma。结合高δEu比值、锆石Ti温度(691~777℃)、Yb-U-Y和Ti-Hf等相关锆石微量元素特征,这些表明月山岩体可能来源于幔源和壳源岩浆的混合。月山岩体的形成可能与洋壳俯冲相关,Cu-Au矿化与岩浆的高氧逸度有关。The Yueshan area, Anhui is one of copper and gold production sites in China, where ore formation is closely related to magmatism. In recent years, opinions are still divided on the origin of Mesozoic intrusion in Yueshan, Anqing. This paper reported latest zircon U-Pb ages, zircon-in- situ trace elements and Hf isotope data of the Yueshan intrusion in Anqing. LA-ICP-MS zircon U-Pb dating indicated that the Yueshan diorite formed at 138.2±1.7Ma（MSWD=0.61 ）. This intrusion has typical magmatic zircon feature： an REE portioning pattern of consistent HREE enrichment, Ce positive anomaly and weak Eu negative anomaly, high Th/U and （Sm/La） N values and low La content. Zircon εHf（t） value is within a range of-10.0 to -5.4 （-7.9 in average）, and two-stage model age（ tDM2 ）1530-1822Ma, which, together with high δEu value, zircon Ti temperature （691-777℃）, Yb-U-Y and Ti-Hf, suggest that the Yueshan intrusion may be sourced from a mixture of mantle and crust magma. The Yueshan intrusion possibly formed in the context of oceanic crust subduction, and Cu-Au mineralization had to do with high oxygen fugacity of the magma.

关 键 词：月山闪长岩 锆石U-PB定年 HF同位素 岩浆混合 安庆 

分 类 号：P579[天文地球—矿物学] O614.413[天文地球—地质学]