中文摘要：

安徽繁昌地区属于长江中下游铁、铜、硫、金成矿带的一部分。区内广泛发育燕山期侵入岩。侵入岩的岩性主要为黑云母石英二长岩至花岗岩，但以花岗岩为主。岩石富含钾长石，SiO：、K20含量明显比铜陵地区中生代侵入岩的要高。锆石SHRIMP法测年表明繁昌板石岭黑云母石英二长岩的形成年龄为（125．3±2．9）Ma，滨江花岗岩的形成年龄为（124．3±2．5）Ma，铜陵侵入岩（鸡冠石花岗闪长岩、小铜官山石英闪长岩）的SHRIMP年龄分别为（135．5±4．4）Ma、（139．5±2．9）Ma，因而确定繁昌侵入岩的形成比铜陵岩体至少要晚十几百万年。岩石的全岩主元素以及微量和稀土元素分析结果表明，繁昌地区的板石岭岩体和浮山岩体为典型的A型花岗岩类，而滨江花岗岩体是岩浆演化到最晚期的产物，形成于与A型花岗岩类似的构造环境，因而暗示125Ma左右是长江中下游地区地壳强烈伸展的阶段。这一研究成果对探讨长江中下游地区早白垩世早期（135～140Ua）与晚期（约125Ma）左右的动力学背景具有重要的意义。

英文摘要：

The Fanchang area, located in northeastern Tongling City of Anhni Province, is a segment of the iron, copper, sulfur and gold metallogenic belt in Middle and Lower Reaches of the Yangtze River. There occur many Mesozoic magmatic intrusions in this area. The lithologies of the intrusions vary from biotite quartz monzonite to granite, but are dominated by granite. The rocks contain a lot of K-feldspar and are rich in potassium. The whole-rock analyses of major, trace and rare earth elements of the rocks indicate that biotite quartz monzonite from the Banshiling intrusion and K-feldspar granite from the Fushan intrusion belong to a typical A-type granitoid association, and granite from the Binjiang intrusion is the product formed in the last period of magmatic evolution and within a similar tectonic setting with that of A-type granite formation. Some of the zircon grains from the Jiguanshi granodiorite and Xiaotongguanshan quartz diorite in Tongling area yield ^207Pb/^206Pb ages of （135.5 ± 4. 4） Ma to （139. 5 ±2.9） Ma, while those from the Banshiling biotite quartz monzonite and Binjiang granite in Fanchang yield the ages of （124.3 ±2.5） Ma to （125.3±2.9） Ma. These data combined with an A-type granitoid association in Fanchang support the occurrence of intensive crustal thinning at 124 to 125 Ma in the late period of extension in Middle and Lower Reaches of the Yangtze River.