南岭成矿带前寒武纪地层区划与岩石地层的厘定

Precambrian stratigraphic regionalization and redefinition of some lithostratigraphic units in Nanling Metallogenic Belt

南岭成矿带前寒武系为金、铁、锰、磷及铅锌的赋矿层位,近年来由于高精度测年数据的应用,建立了较为清晰的年代地层格架,然而由于历史原因,前寒武系岩石地层序列在湘黔桂赣粤交界地区存在同物异名现象,不利于地质矿产图的编制,需要重新厘定完善。本文以武陵运动构造面为界,将南岭成矿带大地构造演化分为两个阶段,按中元古代至青白口纪早期、青白口纪晚期至震旦纪划分出不同地层区。早期划分出两个地层区—扬子与华夏地层区,晚期同属于华南地层区,依据处于盆地不同位置,再划分为六个地层分区。本文重点对湘黔桂交界地区的青白口系上部层位、赣湘桂地区南华系和震旦系进行了梳理,初步形成前寒武纪岩石地层序列,不再采用部分岩石地层单位,以便于编制该地区地质矿产图。

Precambrian system in Nanling Metallogenic Belt is the layer of occurrence of gold, iron, manganese,phosphorus, and lead zinc. Chronostratigraphic framework has been well-grounded redefined, based on publication of a series of high accuracy dating data. Meanwhile, synonyms, which have negative effects on geological mapping, still occur in stratigraphic sequences of Precambrian System of the area, and that should be elaborately redefined. In this paper, stratigraphic regionalization of Mesoprotozoic to early Qingbaikouan and late Qingbaikouan to Sinian in Nanling Metallogenic Belt differ on the basis of two stages of tectonic evolution, which could be divided by angular unconformity between Lengjiaxi and Banxi Groups, generated by Wuling Orogeny. Early stage is divided into Yangtze and Cathaysian stratigraphic regions; and the late into six stratigraphic sub-regions, all of which belong to South China region, according to their different locations in the depression. The paper focuses on teasing out the upper part of Qingbaikouan System in borderland of Hunan, Guizhou and Guangxi, together with Nanhua to Sinian Systems in Jiangxi, Hunan and Guangxi, abolishing some lithostratigraphic units＇ names, in order to develop uniform standard of lithostratigraphic sequences in convenience of geological mapping of this area.