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高εNd(t)-εHf(t)花岗岩是研究陆壳生长的有力证据.哀牢山构造带中段滑石板花岗岩样品激光锆石U-Pb年代学、Lu-Hf同位素和全岩主微量元素、Sr-Nd同位素分析结果表明其为高硅(SiO2=72.66wt%~73.70wt%)、低镁(Mg#=0.28~0.34)、弱过铝质(A/CNK=1.01~1.05)的高钾钙碱性I型花岗岩,具有正的εNd(t)值(3.28~3.55).其中两个样品的锆石206Pb/238U加权平均年龄分别为(229.9±2.0)和(229.3±2.3)Ma,对应的εHf(t)分别为9.8~12.6和8.4~13.1.229 Ma代表了花岗岩结晶年龄,结合对近年来国内外关于哀牢山深变质杂岩的年代学资料的统计分析,可以认为哀牢山深变质岩并非前人所认为的是扬子地台前寒武纪结晶基底的一部分,而是由中元古代、新元古代、海西早期、印支期和喜马拉雅期等不同时代岩石组成的变质杂岩.滑石板高εHf(t)花岗岩的形成经历了两个阶段:二叠纪受到流体、熔体交代的地幔楔部分熔融底侵到下地壳形成岛弧下地壳;晚三叠世碰撞后阶段上涌的软流圈地幔热导致新生下地壳重熔.滑石板高εNd(t)-εHf(t)花岗岩记录了哀牢山构造带经历过的一次地壳增生事件.
The high εNd (t) -εHf (t) granite is a strong evidence for the study of continental crustal growth.The zircon U-Pb chronology, Lu-Hf isotope and the main rock trace elements in the mid- The results of Sr-Nd isotope analysis indicated that the high-silicon (SiO2 = 72.66wt% -73.70wt%), low magnesium (Mg # = 0.28-0.34) and weak perchlorate (A / CNK = 1.01-1.05) The calc-alkaline I-type granites have positive εNd (t) values (3.28-3.55), and the weighted average 206Pb / 238U zircon ages for the two samples are 229.9 ± 2.0 and 229.3 ± 2.3 Ma, respectively ΕHf (t) of 9.8 ~ 12.6 and 8.4 ~ 13.1.229 Ma, respectively, represent the granite crystallization age. Combined with the statistical analysis of the geochronological data of Ailaoshan deep metamorphic complex at home and abroad in recent years, Deep metamorphic rocks are not considered as part of the Precambrian crystalline basement of the Yangtze platform. They are composed of metamorphic rocks of different ages such as Mesoproterozoic, Neoproterozoic, Early Hercynian, Indosinian and Himalayan periods Complex formation of talc high-εHf (t) granites experienced two stages: the mantle wedge partially infiltrated by fluids and melts in the Permian The crust formed an arc-arc crust, and the upwelling asthenospheric mantle caused the re-melting of the new crust during the Late Triassic post-collision stage. The talc height εNd (t) -εHf (t) granite recorded the Ailaoshan structural belt Once a crustal proliferation event.