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详细的激光拉曼光谱分析,在陕西丹凤县城东北部的秦岭岩群斜长角闪岩锆石中发现柯石英、绿辉石、石榴子石和金红石等多种矿物包裹体.柯石英具有典型的524 cm?1主峰以及270和151 cm?1次峰的拉曼光谱组合,绿辉石显示680 cm?1拉曼特征峰.柯石英、石榴子石和绿辉石显微包裹体的发现证明,丹凤斜长角闪岩应该是退变的超高压榴辉岩,变质的峰期压力>2.8 GPa.利用LA-ICP-MS锆石原位U-Pb定年方法,结合锆石CL图像特征、显微包裹体分布和微量元素组成,得到丹凤含柯石英斜长角闪岩的峰期变质时代为496.9±2.5 Ma,并同时得到451.7±4和425.8±3.3 Ma两期叠加变质事件年龄.丹凤斜长角闪岩锆石包裹体中柯石英的发现以及年代学研究结果与前人在邻区斜长角闪岩锆石包裹体中微粒金刚石的发现和490.4±5.8 Ma峰期变质年龄的获得,以及秦岭岩群已有榴辉岩和超高压长英质片麻岩普遍获得的~500 Ma的峰期变质以及~450和~420 Ma的后期构造事件叠加完全一致,表明北秦岭构造带的秦岭岩群在~500 Ma的早古生代确实经历过超高压变质作用,存在巨量陆壳物质的深俯冲.
Detailed laser Raman spectroscopic analysis shows that many mineral inclusions such as coesite, omphacite, garnet and rutile are found in the amphibolite from the Qinling Group in the northeast of Danfeng County in Shaanxi Province. Of the 524 cm? 1 main peak and the Raman spectra of the 270 and 151 cm? 1 peaks, and omphacite shows a 680 cm? 1 Raman peak. The discovery of coesite, garnet and omphacite inclusions demonstrated that Dan The phlogoid amphibolite should be a degenerated UHP eclogite with a peak metamorphic peak pressure of> 2.8 GPa. Using the LA-ICP-MS zircon U-Pb zircon dating in combination with zircon CL image characteristics, Inclusions and trace elements, the peak metamorphic age of the Danfeng-coesite amphibolite is 496.9 ± 2.5 Ma, and 451.7 ± 4 and 425.8 ± 3.3 Ma superimposed metamorphic events are obtained at the same time. Discovery of cristobalite in zircon inclusions from plagioclase amphiboles and the results of chronology and the discovery of microparticulate diamond in the zircon inclusions of the plagioclase amphiboles in the adjacent area and the acquisition of the metamorphic age of 490.4 ± 5.8 Ma , And the Qinling Rock Group has eclogite and ultra-high pressure feldspathic gneiss generally received The peak metamorphism of ~500 Ma and the superposition of late tectonic events of ~450 and ~420 Ma are consistent, indicating that the Qinling Group in the North Qinling tectonic belt did experience UHP metamorphism at ~ 500 Ma in the Early Paleozoic, Deep subduction of continental crustal matter.