(1. 中南大學有色金屬成礦預測與地質環(huán)境監(jiān)測教育部重點實驗室，長沙 410083；
2. 中南大學地球科學與信息物理學院，長沙 410083)
摘 要: 通過系統(tǒng)地分析巖石地球化學、LA-ICP-MS鋯石U-Pb年代學和鋯石Hf同位素組成，對巖石的成因進行研究。結果表明：八團巖體中的鋯石晶形完好，內部結構清晰，震蕩生長環(huán)帶發(fā)育，具有較高的Th/U比值(0.42~0.61)，顯示巖漿成因的特征。對八團巖體LA-ICP-MS的U-Pb定年結果為(159.2±4.6) Ma(MSWD=0.62)，表明其屬于燕山期巖漿侵入活動的產物。八團巖體屬于硅酸過飽和巖石，具有富鈉富鉀低鈣的特征，鋁飽和指數A/CNK值均大于1.1，同時又兼具Rb、Th強烈富集，Nb、Sr、Ti強烈虧損的特點，巖體中輕稀土富集強烈，重稀土虧損嚴重，稀土配分曲線均向右傾且具有明顯的負Eu異常，八團巖體中εHf(t)值為-36.03~-6.09，以上特征說明八團巖體屬于典型的S型花崗巖，是由地殼經不同程度熔融而成的。
關鍵字: 地球化學；鋯石U-Pb年代學；Hf同位素；八團巖體
（1.Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitor,
Ministry of Education, Central South University, Changsha 410083, China？
2. School of Geosciences and Info Physics, Central South University, Changsha 410083, China）
Abstract:Base on the detail analysis of geochemistry, LA-ICP-MS zircon U-Pb chronology and Hf isotopic composition about the intrusion, the genesis of granite was discussed. The results show that zircons from the intrusions display complete crystal form, clear internal structure and oscillatory zoning and high Th/U ratios (0.42-0.61), implying their magmatic origin. LA-ICP-MS zircon U-Pb dating results of the Batuan intrusion indicate that the product is Yanshanian magmatic activity with the intercept ages of (159.2±4.6) Ma(MSWD=0.62). Batuan intrusion is a supersaturated silicate rocks with the characteristics of rich sodium and potassium and low calcium. A/CNK aluminium saturation index values are greater than 1.1. At the same time, the intrusion has the characteristics of strong enrichment of Rb and Th, and strong depletion of Nb, Sr, Ti. The rock mass strongly enriches the light rare earth and strongly depletes in the heavy rare earth, rare earth distribution curve inclines to the right and has obvious negative Eu anomaly. The εHf(t) of Batuan intrusion is -36.03~-6.09. Taken together, Batuan intrusion is S-type one formed by the earth crust melt.
Key words: geochronology; zircon U-Pb dating; Hf isotope; Batuan intrusion
