北秦岭含金刚石-柯石英超高压榴辉岩广泛受到角闪岩相退变质作用叠加改造。区内已有的年代学工作主要集中在探讨榴辉岩相变质作用的时代。角闪岩相退变质作用时代，仍然缺乏精确的年代学工作，致使超高压变质岩的折返时限和机制仍不明确。本项目以北秦岭官坡-双槐树地区榴辉岩-片麻岩为研究对象，从榴辉岩及其退变质产物榴闪岩和围岩片麻岩着手，以40Ar/39Ar定年为主要技术手段，结合野外考察、室内矿物学、岩石学和地球化学研究，来探讨榴辉岩与围岩的变质P-T条件，限制榴辉岩角闪岩相退变质作用以及后期热构造事件叠加发生的时代，为原有的超高压变质岩折返机制提供可靠的年代学数据支撑。同时通过激光阶段加热、真空击碎提取流体包裹体和粉末阶段加热40Ar/39Ar定年技术的综合使用，探讨超高变质过程中形成的角闪石外来40Ar赋存机制及可能来源，为含外来40Ar的退变质角闪石矿物40Ar/39Ar年代学研究开辟新途径。

The ultra-high pressure metamorphic (UHP) metamorphic eclogites in the North Qinling terrane, central China, containing coesites and microdiamonds, have been widely retrograded into amphibolites. Previous geochronological studies on these UHP rocks focused on the timing of the peak eclogite facies metamorphism. Study on timing the retrograde metamorphism and exhumation history, however, is rather rare. As a result, the exhumation mechanism of these UHP metamorphic rocks is still a controversial issue. Systematic field geology, mineralogy, petrology and geochemistry, and 40Ar/39Ar geochronology study will be promoted in this project for the eclogites and their retrogressed equivalent rocks, i.e., garnet-amphibolite and amphibolite, as well as host rocks gneisses of the Guanpo-Shuanghuaishu area, north Qinling terrane. In a comprehensive analysis of the petrographic and 40Ar/39Ar data, we aim to: (1) constrain the age of the amphibolite facies retrograde metamorphism, and (2) provide insight into the exhumation rates, to subsequently afford a better resolved P-T-t path of the post UHP evolution of this retrograde eclogite and its host rock. Moreover, applying combined laser stepwise heating, crushing in vacuo and powder stepwise heating 40Ar/39Ar techniques on these amphibole samples, not only provides information to directly constrain the timing of fluid activity and the age of amphibolite-facies retrogression, but also opens a new way to systematic to investigate the Ar composition and decipher its occurrence characteristic and origin of extraneous 40Ar.