新一轮岩相古地理编图对华南重大地质问题的反映——早古生代晚期'华南统一板块'演化

摘要

以板块级别的小比例尺岩相古地理编图为手段,重塑和反映构造-盆地演化过程,可为探讨重大地学问题提供线索依据.从华南大区古地理重建的角度,对构造学者提出的"华南统一板块"和加里东晚期"陆内造山"模式给予验证.研究表明:以往认为属不同构造单元的扬子陆块和华夏地块之间,沉积相配置为连续过渡、符合瓦尔特相律,没有分隔盆地的重大构造界线,指示华南残留洋盆并不存在.早古生代晚期的古地理演化并未反映出洋盆消减、被动大陆边缘向前陆盆地转换,而是板内挤压的造山、造陆过程,可分为板内地壳调整(中奥陶世至早志留世鲁丹期)和板块整体抬升(早志留世埃隆期至志留纪末)两个阶段.其实质是在构造转型背景下,华南板块从松散到紧合的"再克拉通化"过程.%Palaeogeographic reconstruction in small scale is one of the most effective method for discussing tectonic-basin evolution in geological time.Recent progresses in lithofacies paleogeographic study on South China provide new clues on the key geological problems in early Paleozoic.The results of our study show that there is no critical tectonic-basin boundary between the Yangtze and Cathaysia block in early Paleozoic, which has a continuous distribution of sedimentary facies in time and spaces.These lines of evidence deny the presence of Huanan remnant-ocean basin in early Paleozoic, and, with the coupled evolution of paleogeography in successive stages, support the hypothesis of one solid South China Plate.The results also support a mountain-basin coupling process inside of South China Plate, instead of transition from passive continental margin to foreland basin system.This process can be considered as re-cratonization of South China Plate in Early Paleozoic.