黑龙江东南部穆棱地区“麻山群”的特征及花岗岩锆石SHRIMPU-Pb定年--对佳木斯地块最南缘地壳演化的制约  

Characteristics of the "Mashan Group" and zircon SHRIMP U-Pb dating of granite in Muling area, southeastern Heilongjiang Province, China: constraint on crustal evolution of the south-ernmost of Jiamusi Massif

作　　者：颉颃强[1,2] 苗来成[2] 陈福坤[2] 张福勤[2] 刘敦一[1] 

机构地区：[1]中国地质科学院地质研究所北京离子探针中心,北京100037 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地质通报》2008年第12期2127-2137,共11页Geological Bulletin of China

基　　金：国家自然科学基金项目(编号:40473030、40525007);中国科学院知识创新工程项目(编号:KZCX2-104)资助。

摘　　要：通过对佳木斯地块南缘穆棱地区常兴村-新兴村剖面的研究,认为这里是"麻山群"和"黑龙江群"的结合部位,具有古大陆边缘的性质。穆棱地区的"麻山群"为佳木斯地块南缘的陆壳基底,其南侧的"黑龙江群"为包括洋壳残片在内的增生-碰撞杂岩。对"麻山群"混合岩的SHRIMP锆石U-Pb定年结果表明:佳木斯地块存在中—新元古代的结晶基底,并遭受到约500Ma变质作用的影响。侵入"麻山群"杂岩的花岗岩的岩石学、地球化学研究表明,这些花岗岩具有S型花岗岩的特征;其SHRIMP锆石U-Pb分析表明,其形成年龄为486Ma±3Ma,略晚于前人确定的"麻山群"杂岩约500Ma的麻粒岩相变质作用,为同碰撞或碰撞后花岗岩。这些资料进一步证明,该地区可能经历了晚泛非—早加里东期的碰撞造山作用。According to the geological profile from Changxingcun to Xinxingcun in Muling, south of Jiamusi Massif, we suggest that assemblage of formations there shows features of paleoactive continental margin. The Mashan Group is the basement of Jiamusi Massif, whereas the Heilongjiang Group represents an accretionary-collision complex containing remnants of oceanic crust. Zircon SHRIMP U-Pb dating on the migrnatite from Mashan Group indicates that there is Mesoproterozoic-Neoproterozoic basement in Jiamusi Mas- sif and it has been influenced by ～500Ma metamorphism. The petrological and geochemical studies on the granite, which intruded the Mashan Group, suggest that they are of affinity of S-type granites. The SHRIMP U-Pb dating indicates that the emplacement of granite occurred in Late Cambrian, with a weighted mean age of 486Ma±3Ma, slightly later than previously defined ～500Ma granulite-facies metamorphism of the Mashan Group. Therefore, these granites are syn- or post-collisional intrusive rocks. These data confirmed that the study area underwent a late Fan-African-Early Caledonian collisional orogenesis.

关 键 词：佳木斯地块 基底 SHRIMP锆石U—Pb定年 S型花岗岩 穆棱地区 

分 类 号：P534.3[天文地球—古生物学与地层学] P597.3[天文地球—地质学]