Correlation of Late Permian basement rocks in the eastern margin of Asian continent on the basis of the CHIME dking

根据副独居石和锆石的钟状定年和全岩成分的XRF分析，对日本群岛和亚洲大陆东缘的基岩进行了对比。主要研究结果如下：(1)南北上地体乌苏吉努砾岩中英云闪长岩碎屑的锆石和独居石年龄为258-247，与晚二叠世化石年龄一致。如果将这些年龄作为源区花岗岩类侵位年龄的代表，则源区一定发生了快速剥蚀。锡霍特-阿林地区的花岗岩类显示250 Ma左右的独居石年龄，可能是乌苏吉努砾岩中碎屑的来源。(2)爱知县奥托瓦-洪果山地区矽线石级Ryoke副片麻岩中的石英长石脉可分为变形脉和非变形脉。变形脉具花束状构造，形成95~90 Ma的独居石年龄。未变形的静脉与Clear-…不协调更多的切割界线，给出了86~77 Ma独居岩的年龄。年龄与脉体变形模式相结合，表明该区变质岩在90~86 Ma期间由韧性变形条件上升为脆性变形条件。(3)中国东南部花岗岩类的钟表测年结果表明，中、晚侏罗世花岗岩在包括黄山、武功山在内的整个内陆地区都很突出，而中白垩世花岗岩主要分布在沿海地区。(4)筑河砾岩的花岗岩碎屑年龄为178+/-3 Ma。这是首次从米诺地体的侏罗系层内砾岩中发现侏罗纪花岗岩类的认证文件，并为该地体碎屑岩的中生代源岩提供了更清晰的线索。(5)索山花岗片麻岩显示1.72Ga嵌合锆石年龄。长期以来，它一直被认为是侵入贡基地块中的并列星云。然而，钟形测年显示，副片麻岩中的独居石和锆石比索山花岗片麻岩中的独居石和锆石年轻得多。副片麻岩与淡色花岗岩脉褶皱在一起，获得了约250 Ma的独居石和锆石年龄。(6)HIGO变质岩中的独居石颗粒与峰期变质矿物组合处于结构平衡状态，并平行于峰期变质过程中发育的强烈矿物面理。所有独居石颗粒的钟声年龄均为110~120 Ma。根据岩石学证据，独居石年龄被解释为代表变质变形的时代。这一结论与认为HIGO片麻岩形成于二叠纪-三叠纪的研究相反。较少

Basement rocks in the Japanese Islands and the eastern margin of Asian continent were correlated on the basis of the CHIME dating of accessory monazite and zircon and the XRF analyzes of whole-rock composition. The main results are as follows.(1) Tonalitic clasts in Usuginu conglomerate of the South Kitakami terrane show 258-247 zircon and monazite ages which are are consistent with the Late Permian fossil age. If these ages are taken as representing emplacement ages of the source granitoids, rapid denudation of the source areas must have occurred. Granitoids in the Sikhote-Alin area show CHIME monazite ages of around 250 Ma, and appear to be a likely source ofclasts in the Usuginu conglomerate.(2) Quartzofeldspathic veins in the sillimanite-grade Ryoke paragneiss in the Otowa-Honguusann area, Aichi Prefecture are classified into deformed and ndeformed veins. Deformed veins show boudinage structure, and give CHIME monazite ages of 95-90 Ma. Undeformed veins are discordant with a clear- … More cut boundary, and give 86-77 Ma monazite age. The ages coupled with the deformation pattern of veins suggest that the metamorphic rocks in the area had been uplifted from the ductile deformation condition to the brittle deformation conditions during the period of 90-86 Ma.(3) CHIME dating of granitoids in southeastern China disclosed that the middle to late Jurassic granites are prominent throughout the inland area including Huangshan and Wugongshan, whereas the middle Cretaceous granites are distributed mainly in the coastal region.(4) A granite clast from the Tsukiyozawa conglomerate shows 178+/-3 Ma CHIME monazite ages. This is the first authenticated document to unveil the existence of the Jurassic granitoid from the Jurassic intraformational conglomerate in the Mino terrane, and provides a clearer clue to the Mesozoic source rock for clastic rocks of the terrane.(5) The Sosan granite gneiss shows 1.72 Ga CHIME zircon age. It has long been considered to be a intrusion emplaced into paragneisses in the G^onggi massif. The CHIME dating, however, show monazite and zircon in the paragneiss are much younger that in the Sosan granite gneiss. The paragneisses were folded together with leucogranite veins which give CHIME monazite and zircon ages of c. 250 Ma. This suggests an intense Late Permian metamorphism in Korean Peninsula.(6) Monazite grains in Higo metamorphic rocks are in textural equilibrium with the peak metamorphic mineral assemblage, and are oriented parallel to a strong mineral foliation developed during peak metamorphism. All monazite grains yield CHIME ages of 110-120 Ma. On the basis of the petrographic evidence the monazite ages are interpreted as representing the time of metamorphism and deformation. This conclusion is contrary to studies which suggest that the Higo gneiss formed during the Permian-triassic. Less