工作区位于西伯利亚板块与华北板块汇聚域, 索伦-西拉木伦河-长春-延吉-黑龙江碰撞缝合带的吉林段。2000年以前, 吉中段没有高压-超高压变质作用实证。为此, 选择长春-盘石-蛟河一带为首要地质调查区。经过综合分析前人区域地质、找矿等资料, 借鉴研究苏鲁-大别板块碰撞的经验及成果。蛟河蓝晶石产地被关注。经过野外精细工作、采集代表性新鲜样品、镜下鉴定和电子探针分析等工作, 喜获关键性鉴定和实测成果。综合成果证明, 产蓝晶石的地质体是经历高压的变质杂岩, 蓝晶石石英岩是达榴辉岩相的变质岩。该发现对确立吉黑高压-超高压碰撞俯冲带具有奠基性的极为重要的意义。该发现于2000年曾做简要报道, 现予详细发表。该榴辉岩相蓝晶石石英岩呈块状、似层状、透镜状和无根勾状体产于吉中地区罗圈沟一大石虎狭长剪切带内。被剪切的岩石为晚古生代早二叠世大河深组和华力西晚期花岗斑岩, 变形变质形成蓝晶石白云母石英片岩和白云母蓝晶石石英岩。峰期矿物组合为蓝晶石、石英、多硅白云母、锆石、金红石和碳硅石, 而无矽线石和斜长石, 基本满足榴辉岩相的约束特征。峰期变质温度达700~750℃, 多硅白云母的Si (pfu) =3. 440-3. 535, 指示变质压力达P=2. 75~3. 30GPa, 显示该岩石经历了超高压变质作用过程, 其温压条件已经与柯石英、金刚石形成的温压条件相当。次峰期温度约550℃~600℃, 压力约1. 60~1. 7GPa。蓝晶石、白云母和石英具有多期性, 表明该岩石在俯冲折返和剥露过程中遭受强烈变形和退变质作用。退变质作用的温压数表明路径先后为角闪岩相、绿片岩相, 其温压分别温度约500℃~450℃, 压力约0. 5~0. 7GPa; 温度约300℃~350℃, 压力约0. 3~0. 4GPa。

The work area is located in the convergence domain of the Siberian plate and North China plate. The Jilin Province of the Soren-Xilamnlun river-Changchun-Heilog jiang plate collision zone. Before 2000, there was no empirical evidence of high-ultrahigh pressure transformation in the middle Jilin section. For this reason, the Changchun-Panshi-Jiaohe area was selected as the primary geological survey area. After comprehensively analysing the previous regional geological and mineral exploration data, we drew on the experience and achievements of studying the collision between the Suiu-dabie plate. Jiaohe blueschist origin was concerned. After fine field investigation, collecting fresh and representative samples, conducting microscopic identification, electron probe analysis and other work, the key identification and measurement results were obtained. Comprehensive results proved that the geological body producing kyanite undergoes high-pressure kyanite-quartzite was a metamorphic rock of gernet pgroxenite facies. This discovery is of fundamental importance for the establishment of the Jihei high pressure human ultra-high-pressure collision subduction zone. The discovery was briefly reported in 2000 and is now being published in detail. The garnet-phase blueschist quartzite is massive, laminated, ienticular, and rootless hook like bodies occur in within the luoguangou Dashihu narrow ductile shear zone. The rock being sheared is late paleozoic Early perntian Daheshan formation and late variscan Granite Porphyry, which were deformed and metamorphosed to form. blueschist dolomite quartz schist and dolomitic blueschist quartzite. The Peak mineral combination is Ky2+Qz2+Ms2 (Phn2) +Zt+Rt+Miss, without Sili and Pl, which basically meets the constraining charactenstics of eciogite facies. The peak metamorphic temperature reaches 700-750℃, indicating the Si (pfu) =3. 440-3. 535 of phengite, and indicated metamorphic pressure reaches p=2. 75-3. 30GPa, which shows that the rock has undergone ultra-high pressure metamorphic process, and its temperature and pressure conditions have been comparable to those formed by coesite. The temperature of secondary peak period of is about 550℃-600℃ and the pressure is about 1. 6-1. 7GPa. The multi-phase nature of the blueschist, muscovite and quartz indicates that the rock is subjected to prosess of subduction exhumation, and exhumation suffering from strong progressional and retrograde metamorphism. The temperature and pressure numbers of the metamorphism indicate that the paths are successively hornblende and green schist phases, with temperatures of about 500℃-450℃ and pressures of about 0. 5-0. 7GPa, and temperatures of about 300℃-350℃ and pressures of about 0. 3-0. 4GPa, respectively.