摘要:长江中下游成矿带A型花岗岩与铀（金）矿床（化）具有密切的时空关系，目前关于A型花岗岩的成因存在较大争议，开展A型花岗岩的成因研究将有助于探讨其与铀（金）矿床的成因联系，为长江中下游成矿带寻找此类矿床提供依据。本文选取了庐枞盆地南部的城山岩体、何家凹岩体和梅林岩体3个典型A型花岗岩体为研究对象，开展了详细的野外观察及室内地球化学分析工作，结合前人的研究成果，深入讨论了这些A型花岗岩的成因。研究结果表明：城山岩体、何家凹岩体及梅林岩体侵位于127 Ma，为庐枞盆地最晚一次岩浆事件的产物，属于A型花岗岩，它们为同源岩浆演化的产物，源区以相当于董岭群的变沉积岩为主并夹杂少量地幔物质，岩浆演化过程以分离结晶作用为主，斜长石和钾长石为主要的分离结晶相。
关键词: 庐枞盆地/
A型花岗岩/
锆石U-Pb定年/
Sr-Nd同位素
Abstract:The A-type granites, which are located in middle-lower reaches area of the Yangtze River, have a close relationship with uranium（gold）deposit. Some issues, particularly origin of the A-type granites, are still under debated. The related research to these A-type granites can enhance the genetic relationship with IOCG deposit, and provide the beneficial information regarding to the prospect direction. In this contribution of study, we systematically document the detailed investigation of three typical A-type granites, consisting of Chengshan, Hejiaao and Meilin intrusions. Combing with the previous results, comprehensive regional geological survey and geochemical analysis have been carried out to reveal the deeper insight with respect to the origin and forming processes of the A-type granites. We argue that the formation age of Chengshan, Hejiaao and Meilin intrusions is 127 Ma, which represents the latest magmatic event in the Lu-Zong Basin and forming in the lithosphere extension-thinning tectonic setting. These granites belong to A-type granites, which is caused by the comagmatic evolution. The original source is dominantly composed of epimetamorphic rock from likely Dongling Group, mixed with some mantle material, and fractional crystallization dominates the forming process, predominating by plagioclase and potassic feldspar.
Key words:Lu-Zong Basin/
A-type granite/
Zircon U-Pb dating/
Sr-Nd isotope
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