本文主要是对铜陵矿集区南部丁桥科学深钻中的碱性辉长岩进行了LA-MC-ICPMS锆石U-Pb定年,年龄为63.54±0.53 Ma,表明碱性辉长岩是新生代岩浆侵入活动的产物.全岩主、微量研究结果表明TK01中的碱性辉长岩富钾(K2O平均为1.75％)、富碱(K2O+ Na2O平均为3.90％)、富钛(TiO2平均为1.58％),富集大离子不相容元素和轻稀土元素,亏损重稀土元素,属于过铝质岩石.SiO2-K2O图解中,样品点落在含钾较高的钾玄岩和钙碱性区域中,岩浆演化过程中有矿物的分离结晶作用.碱性辉长岩的锆石εHf(t)值介于-4.7～11.5.推测TK01中的碱性辉长岩主要来源于富集地幔,稍有陆壳物质的混染,岩浆形成于大陆板内拉张的构造背景.%LA-MC-ICP MS zircon U-Pb dating yielded the age of 63.54 ± 0.53 Ma for alkali gabbro from science deep drilling TK01 in Dingqiao,southern Tongling ore district.The age of alkali gabbro indicates intrusive magma activity in Cenozoic period.Major and trace elements suggest these igneous rocks in TK01 are characterized by high content of potassium (K2O 1.75 ％ on average),rich alkali (K2O + Na2O 3.90 ％ on average),titanium (TiO2 1.58％ on average) and LREEs,thus belonging to peraluminous series.In addition,samples fall in shoshonite and calcium alkaline area in SiO2 K2O diagram.Mineral fractional crystallization occurred during the evolution of magma.εHf(t) values of alkali gabbro are-4.7～-11.5.It is inferred that alkali gabbros in TK01 were derived from enriched mantle with less contamination by continental material,and that the magma formed in the tectonic setting of continental intraplate extension.
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