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为了确定松辽盆地基底变质岩的形成时代,对位于盆地南部基底中的6个变质岩和一个火山角砾岩中的变花岗岩角砾进行了锆石LA-ICP-MSU-Pb定年.松辽盆地南部基底变质岩包括变辉长岩(L45-1)、斜长角闪岩(SN117)、变流纹质凝灰岩(G190)、绢云片岩(N103)、绿泥片岩(T5-1)、黑云母阳起石石英片岩(Y205)和变花岗岩(角砾)(L44-1).锆石阴极发光(CL)图像显示,变辉长岩和变花岗岩(角砾)中锆石均具有岩浆成因的核和变质的增生边,其核部定年结果分别为(1808±21)和(1873±13)Ma;斜长角闪岩和绿泥片岩中的锆石具有生长环带,显示基性火成岩中锆石的特征,其定年结果分别为(274±3.4)和(264±3.2)Ma;变流纹质凝灰岩和绢云片岩中的锆石均具有典型岩浆生长环带,样品G190和N103的定年结果分别为(424±4.5)和(287±5.1)Ma;黑云母阳起石石英片岩(Y205)中多数锆石呈浑圆状,且吸收程度不同,暗示其原岩应为沉积岩,其定年结果显示多组谐和年龄,包括(427±3.1),(455±12),(696±13),(1384±62),(1649±36),(1778±18),(2450±9),(2579±10),(2793±4)和(2953±14)Ma.以上定年结果表明,松辽盆地南部存在前寒武纪结晶基底(1808～1873Ma),其存在可能与构造推覆作用有关;同时,盆地基底中还存在早古生代(424～490Ma)和晚古生代(264～292Ma)岩浆作用.上述认识与基底中黑云母阳起石石英片岩中碎屑锆石的定年结果相吻合.
In order to determine the formation age of basement metamorphic rocks in the Songliao Basin, zircon LA-ICP-MSU-Pb zircon dating was performed on six metamorphic rocks in the basement of the southern basin and a granitic breccia in a volcanic breccia. The basement metamorphic rocks in the southern part of the basin include gabbro (L45-1), amphibolite (SN117), albite tuff (G190), sericite schist (N103) Biotite Yangsheng quartzite schist (Y205) and metamorphic granite (L44-1) .The zircon cathodoluminescence (CL) images show that zircons in both gabbro and granite (breccia) The nuclei of the origin nuclei and metamorphic accretion margins are (1808 ± 21) and (1873 ± 13) Ma, respectively. The zircons in the amphibolite and chlorite schist have a growth zone and show a basic The zircons in igneous rocks are characterized by (274 ± 3.4) and (264 ± 3.2) Ma, respectively. The zircons in the variatitic tuffs and sericite schist all have typical magmatism zones. Samples G190 and N103 (424 ± 4.5) and (287 ± 5.1) Ma, respectively. Most of the zircons in the biotite Yangling quartzite schist (Y205) are rounded and have different degrees of absorption, suggesting that the original rocks should be Sedimentary rocks, the dating results show that the number of groups of harmonic and age, including (427 ± 3.1), (455 ± 12), (696 ± 13), (1384 ± 62), (1649 ± 36), (1778 ± 18) 2450 ± 9), (2579 ± 10), (2793 ± 4) and (2953 ± 14) Ma.The results of the above dating show that Precambrian crystalline basement (1808-1873 Ma) exists in southern Songliao Basin, Meanwhile, the Early Paleozoic (424 ~ 490 Ma) and Late Paleozoic (264 ~ 292 Ma) magmatism also exist in the basement of the basin, which is consistent with the dating of detrital zircons in the biotite-quartzite schists in the basement The results match.