对赣东北晚古生代放射虫的初步认识

基于以往大量的研究成果和基本地质事实,人们已认同江南造山带是一个新元古代的碰撞造山带,最近,一些研究者根据在赣东北新元古代蛇绿混杂岩带中发现的晚古生代含放射虫硅质岩,认为该蛇绿岩带中的硅质岩至少是晚古生代的产物,进而提出一个解体江南古陆、江南地区普存在晚古生代一中生代板溪洋的命题根据野外调查、室内化学分析等综合研究,本文认为赣东北含放射虫硅质岩是大陆边缘浅水相沉积产物,稀土元素特征不支持大洋地壳上的深水环境,强烈的印支期构造事件有可能使晚古生代含放射虫硅质岩发生构造运移,并与新元古代蛇绿岩彼此混杂。

Notes on Late Paleozoic Radiolarians of Northeastern Jiangxi Province

Based on lots of study results and geologic evidence, the Jiangnan belt has been considered as a Neopro-teroic collision erogenic belt. Recently, some researchers found Late Paleozoic radiolarian cherts in Neoprotero-zoic ophiolitic melange blocks in the Northeastern Jiangxijthus they proposed that the cherts in the ophiolitic melanges are at least the Late Paleozoic product. From this viewpoint, they further suggested that the Jiangnan craton may have broken up and that a Paleozoic ocean, called the "Banxi Ocean", occurred in this region. According to synthetic researches on the lithology, geochemistry and so on, the authors suggest that the radiolarian cherts belong to continental-margin shallow-water sediments, and the REE patterns of the cherts do not support the viewpoint of deep-water environment above oceanic crust. The strong Indosinian tectonic event may have caused these rocks to be displaced at first and then mixed with Neoproterozoic ophiolitic rocks.