华北克拉通南部早前寒武纪基底形成与演化

简要总结了华北克拉通南部鲁山地区、小秦岭地区、登封及中条山地区的早前寒武纪地质事件序列及其地质意义,并对各地区地质特征和变质演化特点进行对比。结合前人研究工作,初步探讨了华北克拉通南部早前寒武纪基底的演化特点、陆壳形成的主要时期和华北南部基底的构造区划等问题,提出几点认识:1)华北克拉通南部鲁山、中条山、小秦岭等地区均有2.7~2.9Ga岩石记录,以英云闪长质-奥长花岗质-花岗闪长质(TTG)岩石为主,它们共同构成华北南缘的古老结晶基底,并经历了新太古代晚期~2.5Ga构造-热事件,标志着华北克拉通南部在新太古代末期可能已经形成统一基底;2)华北克拉通南部主要的陆壳形成时期为中太古代晚期-新太古代,与全球其他主要克拉通一致,而古元古代早-中期则以地壳再循环为主;3)综合地质、地球化学等特点,将华北南部鲁山-小秦岭地区和中条山等地区划归为"南部古陆块",并提出该陆块呈现为一个大型的倾伏向斜构造,可能在新太古代晚期已经形成,其枢纽向南东倾斜。"南部古陆块"在新太古代末期与其它微陆块拼合,并发生了变质作用和陆壳的活化与再循环,共同指示新太古代晚期华北克拉通统一基底的形成。

.Formation and evolution of Early Precambrian basement in the southern North China Craton

The article summarized Early Precambrian geological events and their geological implications in the Lushan, Xiaoqinling, Dengfeng and Zhongtiaoshan areas in the southern North China Craton, and compared the characteristics of their geological features and metamorphic evolution. Based on the former research, we preliminarily discussed the formation and evolution of Early Precambrian basement, the main period for the formation of continental crust, and tectonic division of the basement in the southern North China Craton, then proposed the following recognitions:1) There were 2.7~2.9Ga rocks dominated by tonalite-trondhjemite-granodiorite (TTGs) rocks exposed in the Lushan, Zhongtiaoshan and Xiaoqinling areas, they together experienced the Late Neoarchean tectono-thermal event, indicating that the southern North China Craton may formed a unified basement in the Neoarchean; 2) The most important formation age of crust occurred during the Late Mesoarchean to Neoarchean period, similar to the characteristic of other major cratons, but the continental recycling mainly took place at the early and middle Paleoproterozoic; 3) Combined with the geological and geochemical characteristics, we outlined the "Southern Ancient Terrane" covered by the Lushan-Xiaoqinling and Zhongtiaoshan areas, and proposed there may be a large plunging syncline formed at the end of Neoarchean, with the hinge dipping toward the east. The final amalgamation between the "Southern Ancient Terrane" and other microcontinent was in the Late Neoarchaean, and then together occurred metamorphism, continental crust activation and recycling, all suggesting that the unified basement of North China Craton were formed in the Late Neoarchaean.