白云鄂博地区早前寒武纪基底岩浆作用和变质作用:锆石SHRIMP U-Pb定年和LA-MC-ICPMS Hf同位素分析  

Magmatism and metamorphism of the Early Precambrian basement in the Bayan Obo area,Inner Mongolia:Zircon SHRIMP U-Pb dating and LA-MC-ICPMS Hf analysis

作　　者：董春艳[1] 马铭株[1] 颉颃强[1] 章雨旭[2] 万渝生[1] DONG ChunYan;MA MingZhu;XIE HangQiang;ZHANG YuXu;WAN YuSheng(Beijing SHRIMP Center,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Chinese Academy of Geological Sciences,Beijing 100037,China)

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]中国地质科学院,北京100037

出　　处：《岩石学报》2021年第2期417-432,共16页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41472167);中国地质调查局项目(DD20190009、DD20190358、DD20190370、DD20190003)联合资助。

摘　　要：白云鄂博位于华北克拉通北缘,是阴山地块的重要组成部分。本文对该区变质基底的5个花岗质岩石样品进行了锆石SHRIMP U-Pb定年,获得了2.63Ga和1.89~2.20Ga的岩浆锆石年龄以及2.47~2.51Ga和1.86~1.94Ga的变质锆石年龄。新太古代早期片麻状英云闪长岩的岩浆锆石ε_(Hf)(t)值和t_(DM2(CC))(Hf)年龄分别为3.57~8.36和2.59~2.88Ga,古元古代中晚期花岗质岩石的岩浆锆石ε_(Hf)(t)值和t_(DM2(CC))(Hf)年龄分别为-17.20~8.58和2.11~3.70Ga。变质锆石与岩浆锆石具有类似的Hf同位素组成。结合前人研究成果,表明:白云鄂博地区存在新太古代早期到古元古代晚期岩浆作用;在每一岩浆作用过程中,地幔添加和壳内再循环都起了重要作用;白云鄂博地区变质基底经历了新太古代晚期-古元古代早期和古元古代晚期构造热事件;阴山地块与南侧孔兹岩带具有类似的早前寒武纪地质演化历史。Bayan Obo area,located along the northern margin of the North China Craton,is an important portion of the Yinshan Block.SHRIMP dating on zircons from five granitoid samples in the Early Precambrian basement of this area yielded Early Neoarchean(2.63 Ga)and Middle to Late Paleoproterozoic(1.89~2.2 Ga)magmatic ages,and Late Neoarchean-Early Paleoproterozoic(2.47~2.51 Ga)and Late Paleoproterozoic(1.86~1.94 Ga)metamorphic ages.Magmatic zircons from Early Neoarchean gneissic tonalite haveε_(Hf)(t)values and t_(DM2(CC))(Hf)ages varying within 3.57~8.36 and 2.59~2.88 Ga,respectively,while magmatic zircons from Late to Middle Paleoproterozoic granitic rocks haveε_(Hf)(t)values and t_(DM2(CC))(Hf)ages varying from-17.2 to 8.58 and 2.11~3.70 Ga,respectively.Metamorphic zircons are similar in Hf isotopic composition to magmatic zircons from the same rocks.Combined with previous work,the following conclusions can be obtained:1)the Early Neoarchean to Late Paleoproterozoic magmatic activities were well developed in this area;2)both the mantle addition and the crustal recycling played important roles in every magmatic process of this area;3)two tectonothermal events were recorded in the metamorphic rocks in this area,occurring at the Late Neoarchean-Early Paleoproterozoic and Late Paleoproterozoic,respectively;4)the Yinshan Block shared similar Early Precambrian geological features with the Khondalite Belt in the south.

关 键 词：SHRIMP定年 新太古代 古元古代 白云鄂博 阴山地块 

分 类 号：P597.3[天文地球—地球化学] P534.1[天文地球—地质学]