对华南早古生代板溪洋的质疑  

IS THE EARLY PALEOZOIC BANXI OCEAN IN SOUTH CHINA NECESSARY?

作　　者：陈旭[1] 戎嘉余[1] D.B.Rowley 张进 张元动[1] 詹仁斌[1] 

机构地区：[1]中国科学院南京地质古生物研究所 [2]芝加哥大学地球物理科学系

出　　处：《地质论评》1995年第5期389-400,共12页Geological Review

摘　　要：许靖华教授等近年来就中国南方大地构造的机制及演化提出了一种新的模式,在国内外引起较大的反响,有助于我国大地构造学的深入研究。笔者等考察了华南从扬子地块至珠江盆地包括板溪群的标准地区在内的早古生代地层及板溪群,发现板溪群本身确为前震旦纪地层,而扬子地块至珠江盆地早古生代在生物相和岩相两方面的连续渐变则说明二者不属于不同的古板块。基于笔者对华南大地构造的认识,提出了一个与许靖华教授等结论不同的更为简单的构造模式,并认为这一构造模式的机制与广西运动有关。Most recently, the 'Banxi' problem has become a focus for discussion of tectonic geology in South China since a new model has been made by Hsu et al. (1988, 1990 etc. ) that the 'Banxi' represents a trench-related flysch and melange complex associated with the closure of a Paleozoic to Early Mesozoic 'Banxi ocean basin'. The nature and age of the 'Banxi' are obviously a matter of controversy. Contrary to the characterization of Hsu et al. , the authors of this paper hold that the Penhsi Group consists of a Late Proterozoic sequence lying unconformably on the Lengjiaxi Group and overlain in turn by the Sinian in Hunan.In this paper, the authors report their observations on the Precambrian, Cambrian, Ordovi-cian and Silurian stratigraphy in northern and central Hunan extending across the Xuefeng Mountains. The change of facies arrangement of Ordovician rocks from Dayong through Taoyuan and Taojiang to Qidong indicates continuous facies changes from carbonate platform through a carbonate ramp to a basinal slope. These changes are marked by the progressive de- crease in carbonate deposits and concommitant increase in argillite content in a southeasterly direction.The paper summarizes the sedimentary features and facies distribution of the pre-Devonian rocks in northern Hunan and then proposes a realtively simple tectonic model. The model presents the interpretation of the geologic ages and contact relations among the various units of eastern South China, which is in agreement with that put forward by many geologists through many years of work but is unlike the interpretation given by Hsu et al. In particular the authors emphasize that the Penhsi in its type region is neither a sequence of trench-fill turbidites nor melanges, but instead marks the earliest drift related sediments of the eastern Yangtze passive margin.

关 键 词：板溪洋 板溪群 扬子被动力缘 早古生代 地质 

分 类 号：P534.4[天文地球—古生物学与地层学]