ABSTRACT

The tectonic nature of Early Palaeozoic Kwangsian orogeny in the South China Block (SCB) is still debated, due to controversy whether there was a Cambrian ocean between the Yangtze Block and the Cathaysia Block. Similarly, continental affinities of the SCB with India and Australia in East Gondwana during the Cambrian are also controversial. Herein, we present detrital zircon U-Pb geochronology of Cambrian sandstone samples from the southern SCB. Cambrian samples (including our new samples and published samples) from the Cathaysia Block and the Yangtze Block show similar detrital zircon age spectra with one prominent age cluster of ~1000-900 Ma and several subordinate age groups, as well as similar cumulative proportion curves (CPC). Such signatures, together with other geological records, suggest that a Cambrian ocean did not exist between the Cathaysia Block and the Yangtze Block, and that Early Palaeozoic Kwangsian orogeny resulted from an intra-continental collision. Cambrian samples from the SCB have much more similar detrital zircon age spectra and CPC to those from Himalaya and Qiangtang than those from Australia, but detrital zircons in Cambrian samples from the SCB, Himalaya, Qiangtang and Australia have a similar prominent age group of ~1000-900 Ma. Thus, the SCB were likely located between Australia and India during the Cambrian, receiving sediments both from India and Australia.

摘要

由于扬子地块和华夏地块之间是否存在寒武纪大洋，华南地块（SCB）早古生代光系造山运动的构造性质仍存在争议。同样，寒武纪期间南海与印度和澳大利亚在东冈瓦纳的大陆亲缘关系也存在争议。在此，我们展示了南华北寒武纪砂岩样品的碎屑锆石 U-Pb 年代学。来自华夏地块和扬子地块的寒武系样品（包括我们的新样品和已发表样品）显示出相似的碎屑锆石年龄谱，具有一个~1000-900 Ma的显着年龄簇和几个从属年龄组，以及相似的累积比例曲线（每次点击费用）。这样的签名，连同其他地质记录，表明华夏地块和扬子地块之间不存在寒武纪海洋，早古生代光州造山运动是由陆内碰撞引起的。SCB寒武系样品与喜马拉雅和羌塘的碎屑锆石年龄谱和CPC相似度远高于澳大利亚，但SCB、喜马拉雅、羌塘和澳大利亚寒武系样品中碎屑锆石具有相似的显着年龄组~1000 -900 毫安。因此，在寒武纪期间，SCB 很可能位于澳大利亚和印度之间，接收来自印度和澳大利亚的沉积物。SCB寒武系样品与喜马拉雅和羌塘的碎屑锆石年龄谱和CPC相似度远高于澳大利亚，但SCB、喜马拉雅、羌塘和澳大利亚寒武系样品中碎屑锆石具有相似的显着年龄组~1000 -900 毫安。因此，在寒武纪期间，SCB 很可能位于澳大利亚和印度之间，接收来自印度和澳大利亚的沉积物。SCB寒武系样品与喜马拉雅和羌塘的碎屑锆石年龄谱和CPC相似度远高于澳大利亚，但SCB、喜马拉雅、羌塘和澳大利亚寒武系样品中碎屑锆石具有相似的显着年龄组~1000 -900 毫安。因此，在寒武纪期间，SCB 很可能位于澳大利亚和印度之间，接收来自印度和澳大利亚的沉积物。