Lushan metamorphic core complex can be divided into eastern and western extensionally-symmetrical detachment tectonic belts,with well-developed extension-detachment and ductile rheology structures.The western detachment belt contains one complete sequence of faulting rocks,with a solid rheological structure zone at top.The vertical stratification of an extensional structural deformation,bounded by the main detachment belt,suggests that the main detachment belt underwent the strongest deformation.Within the eastern detachment belt are developed mylonite zone and tectonic schist (gneiss) zone,and no other structures have been found on the surface.The extensional structure within the eastern detachment belt was developed on the early sinistral shear structures which were superimposed and modified.The formation temperatures of the eastern detachment belt were estimated 500～580℃ and 580～700℃ based on microscopic deformation characteristics of minerals,and the metamorphic temperature calculated by Tiin-biotite geothermometer was 613 ～ 698 ℃.This reveals that the metamorphism of the eastern detachment belt reached the high amphibolite facies during the formation stage.The metamorphic temperature and pressure of plagioclasite-hornblende schist within the western detachment belt were 666 ～ 691℃,0.65～0.75 GPa respectively,calculated by amphibole-plagioclase geothermometer and M-in-hornblende barometer.It shows that the western detachment belt formed under the high P-T conditions and large burial depth.The condition of high amphibolite facies is consistent with the eastern detachment belt.Zircon U-Pb dating yielded an extension age of 138.9 Ma for the eastern detachment belt,which is earlier than that of magmatic activity,but consistent with the western detachment belt.It can be speculated that the western detachment belt was the original detachment belt of Lushan metamorphic core complex,while the eastern detachment belt was the secondary detachment belt formed by gravitational equilibrium with diapirism and folding.%庐山变质核杂岩发育的拆离带分为东、西两条,伸展拆离和韧性流变构造发育,且具有伸展对称性.西侧拆离带内断层岩序列完整,上部为一固态流变构造带,以主拆离带为分界形成一个伸展构造变形的垂向分层变形域,主拆离带处变形最强.东侧拆离带主要发育糜棱岩带和构造片岩(片麻岩)带,其他构造层未见出露,其伸展拆离构造是叠加和改造早期左行剪切构造发育的.东侧拆离带内矿物的显微变形特征估算变形温度为500～580℃和580～700℃,又利用黑云母Ti温度计得到613～698℃的变质温度.角闪石-斜长石地质温度计和角闪石全铝压力计计算西侧拆离带内斜长角闪片岩的变质温度为666～691℃,压力为0.65～0.75GPa,说明西侧拆离带形成时的温压条件较高,埋深较大,与东侧拆离带一样达到了高角闪岩相.通过锆石年代学的研究得到东侧拆离带的伸展年龄为138.9Ma,与西侧拆离带一致,伸展早于岩浆,推测庐山变质核杂岩的原始拆离带是西侧拆离带,东侧拆离带是在重力均衡调节产生的底辟、褶皱作用下形成的次级拆离带.
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