小兴安岭南段翠峦杂岩体成因及构造环境：来自地球化学及锆石Hf同位素的证据

通过对黑龙江省小兴安岭南段中奥陶世翠峦杂岩体的年代学、岩石地球化学、锆石Hf同位素特征的研究，探讨岩体的形成时代、成因、物质来源和构造背景。采用LA−ICP-MS锆石U−Pb定年，获得花岗闪长岩和二长花岗岩样品的年龄分别为463±2 Ma和462±2 Ma，时代为中奥陶世。全岩地球化学研究表明，岩石均具有高Si、高K富碱，贫Ti、Mg、Fe、P等特征。大离子亲石元素K、Rb富集，高场强元素Ti、Nb、Ta、P和HREE亏损，具有显著的负Eu异常（δEu=0.38~0.64），以上都显示岩浆的壳源特征。花岗闪长岩锆石的εHf(t)=2.4~ 3.4，数值集中且均分布于球粒陨石线之上，暗示岩浆源区为新生陆壳物质的部分熔融；地壳模式年龄TDMc=1070～1128 Ma，证实该地区存在中元古代地壳增生事件。本次研究认为，翠峦杂岩体形成于洋陆板块俯冲的构造环境。

Genesis and tectonic setting of Cuiluan plutonic complex in the south section of the Xiaoxing'an Mountains: Evidences of geochemical and zircon Hf isotope

This paper studies the chronology, rock geochemistry and zircon Hf isotopic characteristics of the Middle Ordovician Cuiluan plutonic complex in the south section of the Xiaoxing'an Mountains in Heilongjiang Province, focusing on the formation age, petrogenesis, magmatic material source and tectonic background of the rock mass. Using laser ablation plasma mass spectrometer (LA−ICP-MS) zircon U−Pb dating method, the ages of granodiorite and granite porphyry samples are dated to be 463±2 Ma and 462±2 Ma, i.e., Middle Ordovician. The study of rock geochemistry shows that both samples are characterized by high Si and K, rich alkali, and poor Ti, Mg, Fe, P, etc. It is enriched in LILE (e.g., Rb, K ), depleted in HFSE (e.g., Ti, Nb, Ta, P and HREE) with significant negative Eu anomalies（δ Eu= 0.38~0.64), which show the crust source characteristics of magma. Zircon εHf (t)=2.4~3.4, the values are concentrated and distributed above the chondrite line, indicating that the magma source area is the partial melting of the new continental crust material. TDMc = 1128~1070 Ma, confirming the existence of Mesoproterozoic crustal accretion events in this area. This study suggests that the Cuiluan complex was formed in the tectonic environment of subduction of oceanic and continental plates.