摘要
本文报道了内蒙古扎兰屯地区铜山组的碎屑锆石U-Pb年代学和Hf同位素分析结果,首次发现中国东北地区记录了泛非造山岩浆事件,并探讨了中国东北微陆块的构造归属。年代学研究表明:(1)扎兰屯地区铜山组碎屑岩最年轻锆石年龄峰值为569 Ma,与泛非造山岩浆活动(东、西冈瓦纳大陆碰撞‒拼贴事件)的时代一致;其他3个峰期年龄为873 Ma、1847 Ma和2073 Ma,与兴安‒艾力格庙地块东北部的基底年龄相对应。(2)锆石Hf同位素显示兴安‒艾力格庙地块与松辽‒浑善达克地块新元古代早期年龄峰值(~900 Ma)的εHf(t)值有正有负,二阶段模式年龄反映其是古元古代地壳再造的产物;额尔古纳地块新元古代(~800 Ma)岩浆岩的εHf(t)值为正高值,二阶段模式年龄与形成年龄相近,为中元古代地壳物质再造的产物,与兴安‒艾力格庙和松辽‒浑善达克地块的新元古代早期基底存在明显差异。(3)兴安‒艾力格庙地块和松辽‒浑善达克地块均记录了泛非造山岩浆事件,揭示其与冈瓦纳大陆东北部存在亲缘性。
This paper reports detrital zircon U-Pb dating and Hf isotopic compositions of the Tongshan Formation in Zhalantun,Inner Mongolia,and discusses the affinity of the microcontinents in the northeastern China.The chronological results show that:(1)the youngest zircon age peak of the Tongshan Formation clastic rocks is 569 Ma,which is consistent with the age of the Pan-African magmatism(the amalgamation of West and East Gondwana);the other three age peaks are 873 Ma,1847 Ma and 2073 Ma,corresponding to the basement ages of the northeast Xing’an-Airgin Sum block(XAB).(2)The Early Neoproterozoic(ca.900 Ma)zircon grains from the XAB and Songliao-Hunshandake block(SHB)have similarεHf(t)values of–4.7 to+6.2,which reveals that the Neoproterozoic rocks in the two blocks were derived from the reworked Paleoproterozoic crust.In contrast,the Early Neoproterozoic(ca.800 Ma)magmatic rocks in the Erguna block(EB)with positiveεHf(t)values and young Hf model ages(1161–1735 Ma)were the products of the reworked Mesoproterozoic crust,which suggests that the early Neoproterozoic basement of the EB is significantly different from those of the XAB and SHB.The XAB and SHB recorded the Pan-African magmatic events,implying an affinity with the NE Gondwana continent.
作者
张佳明
徐备
颜林杰
王炎阳
ZHANG Jiaming;XU Bei;YAN Linjie;WANG Yanyang(MOE Key Laboratory of Orogenic Belts and Crustal Evolution,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Key Laboratory of Regional Geology and Mineralization,Hebei GEO University,Shijiazhuang 050031,Hebei,China)
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2021年第2期356-369,共14页
Geotectonica et Metallogenia
基金
国家自然科学基金项目(41672214)
中国地质调查局项目(DD20189612、DD20190004)联合资助。
关键词
铜山组
碎屑锆石年龄
泛非造山运动
冈瓦纳大陆
中国东北微陆块
Tongshan Formation
detrital zircon ages
Pan-African Orogeny
Gondwana continent
microcontinents of NE China
