大别山南缘翁门杂岩中太古代‒古元古代岩浆构造热事件的识别及其地质意义  

Identification of Mesoarchean to Paleoproterozoic Magmatic Tectono-Thermal Events from Wengmen Complex in Southern Dabie Orogen and Its Geological Significance

作　　者：徐大良 彭练红[1] 邓新 徐扬 刘浩[1] Xu Daliang;Peng Lianhong;Deng Xin;Xu Yang;Liu Hao(Wuhan Center of China Geological Survey(China Central South China Innovation Center for Geosciences),Wuhan 430205,China;Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey,Wuhan 430205,China)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉430205

出　　处：《地球科学》2023年第11期4072-4087,共16页Earth Science

基　　金：中国地质调查局花岗岩成岩成矿地质研究中心开放基金课题(No.PMGR202014);中国地质调查局地质调查项目(Nos.DD20190050,DD20221634).

摘　　要：翁门杂岩是在最近的专题地质填图工作中新识别的一套早前寒武纪变质基底,为深入研究扬子陆块北缘大别山早期陆壳形成与演化提供了新的窗口.选择翁门杂岩中代表性花岗质岩类开展了锆石LA-ICP-MS U-Pb年代学和Hf同位素研究.结果表明,2件英云闪长质片麻岩分别形成于2914±24.5 Ma和2874±6.6 Ma,2件二长花岗质片麻岩的形成年龄分别为2669±10.7 Ma和2644±7.1 Ma,1件糜棱岩化二长花岗岩形成于2454±6.5 Ma,证实了大别山南缘存在太古宙‒古元古代早期陆壳基底.同时定年结果显示,2件眼球状花岗质片麻岩的形成时代分别为2011±6.3 Ma和2010±5.4 Ma,部分太古宙岩石中亦记录了古元古代~2.0 Ga变质锆石年龄,表明翁门杂岩曾卷入了古元古代造山事件.现有资料表明新发现的翁门杂岩与扬子陆核太古宙‒古元古代早期构造岩浆热事件和地壳增生时间具有可对比性,但大别山周缘以广泛发育与全球主要陆块一致的~2.5 Ga构造热事件而显示出独特性,可能是古老陆块最终成熟稳定化的记录,标志着组成扬子陆块北缘的各基底在该期可能共处于Sclavia超级克拉通的不同部位,而翁门杂岩所在的大别山周缘可能更靠近该超级克拉通的边缘.The Wengmen complex,a newly identified Early Precambrian metamorphic basement with shallow metamorphism,opens a fresh avenue for future research on the formation and evolution of the early continental crust of the Dabie orogen on the northern Yangtze Block.In this paper,it presents a comprehensive study of in situ zircon U-Pb geochronology and Hf isotopes of representative meta-granitic rocks from the Wengmen complex.The results show that two meta-tonalite gneisses were formed at 2914±24.5 Ma and 2874±6.6 Ma respectively,two monzonitic granitic gneisses were formed at 2669±10.7 Ma and 2644±7.1 Ma respectively,and one mylonitized monzonitic granite was formed at 2454±6.5 Ma,which confirms the existence of Archean to Early Paleoproterozoic continental crust basement in the southern Dabie orogen.The dating results also show that the formation ages of the two eyeball-like granitic gneisses are 2011±6.3 Ma and 2010±5.4 Ma,respectively.Moreover,ca.2.0 Ga metamorphic zircon age has been obtained from the Wengmen Archean rocks,indicating that the complex may have been involved in the Paleoproterozoic orogenic event.The available data indicate that the newly discovered Wengmen complex in the southern Dabie orogen and the Kongling complex in the Yangtze continental core have synchronous tectono-magmatic thermal events and crustal accretion history during the Archean to Early Paleoproterozoic.However,the periphery of the Dabie orogen shows uniqueness due to its well-developed~2.5 Ga tectono-magmatic thermal event,which is consistent with those of the ancient continental blocks in the world and may be the record of the final maturation and stabilization during the end of the Archean.Integrating the new and published data,it proposes that each basement on the northern Yangtze Block maybe coexisted in different parts of the Sclavia supercraton at the end of the Neoarchean,and the periphery of the Dabie orogen represented by the Wengmen complex maybe was located closer to the margin of the supercraton.

关 键 词：大别造山带 变质杂岩 太古宙 古元古代 锆石 地壳生长与再造 超级克拉通 构造地质学 

分 类 号：P54[天文地球—构造地质学] P56[天文地球—地质学] P597