太古宙陆壳增生的断陷构造盆地模式

The Archean Continental Crust Growth and Evolution:A Fault-Sagduction Basin Geotectonic Model

针对太古宙有无类现代的板块构造这一问题,首先探讨了太古宙的陆核以及绿岩带的形成,认为,在弧后盆地出现之前,太古宙地壳增生与演化的主要样式更可能是非板块的。依据华北五台绿岩带和遵化绿岩带的共同特点:(1)绿岩带都位于不同年龄的两个古陆核的结合部位;(2)绿岩带底部通常都有相当厚的陆源碎屑岩,在不整合面之下可见更老基底,向上可以与火山岩连续沉积;(3)绿岩带通常形成独立完整的复向斜盆地,提出了在古陆核结合部位由断陷盆地进一步发展为太古宙绿岩带的构造模式。认为该模式存在3个主要的发展阶段,即太古宙早期古陆核形成和对接、在古陆核对接处形成断陷盆地以及在地幔柱活动影响下断陷盆地发展成为绿岩带。而这一模式作为太古宙弧后盆地开始发育之前的前板块时期大陆壳增生的主要样式仍有待更多实例的确证。

This paper hereby tries to summarize the common features based on observations on Wutai and Zun-hua-Miyun greenstone belts in North China： （ 1 ） The greenstone belts are located at the junction of two Ancient continental nucleis with different ages and histories; （2）There are usually terrigenous clastic rocks with unconformity contact at the bottom of the greenstone belts and it can be deposited continually with different kinds of volcanic series; （3）The greenstone belts usually form independent and complete synclinorium basins. The fault-sagduction basin geotectonic model can be established on these evidences and other findings. The faultsagduction basin is developed on the junction between initial continental nuclei and further transited to the making of greenstone belts, which is the main pattern for the Archean continental growth and evolution in the preplate tectonics period prior to the initiation of back-arc basin in Late Archean. In addition, this model should be further confirmed with more observations and facts.