扬子陆块西部古隆起演化及其对郁南运动的反映

摘要

寒武纪—奥陶纪之交的郁南运动是华南重要构造事件，但以往研究与认识局限于中国东南部。同期构造运动对扬子陆块的影响尚不明确，制约了对郁南运动的全面理解。本文以扬子陆块西部为例，分析芙蓉统（末寒武统）至下奥陶统地层接触关系，特别是地层不整合面分布，重建了古隆起演化过程并初步探讨其机制；在各期沉积相和岩相古地理演化基础上，总结了盆山耦合与沉积响应特征。结果表明：寒武纪—奥陶纪之交的构造运动在扬子陆块西部有显著表现，反映为大规模古隆起形成、相对海平面和沉积相配置变化；其机制与克拉通边缘基底古陆对地壳位移、变形的阻挡有关，从板块尺度上看，可能是扬子陆块东南侧构造挤压在陆块西部的同步响应。据此笔者提出，寒武纪—奥陶纪之交的华南存在广义的、可对比的“郁南运动”，可能是早古生代构造—盆地性质由拉张向挤压转型的重要节点。%The significant tectonic event,which occurred during the transition of Cambrian to Ordovician,has been well-known as Yunan orogeny in SE China.However,the studies on simultaneous tectonic movement and its effect in the Yangtze plate were few.In this paper,we detail the characteristics of stratigraphic unconformities, sedimentary sequences and lithofacies paleogeography in the western Upper Yangtze during Furongian to Lower Ordovician.The results show that a large area of paleo-uplifts developed with significant changes in the sedimentary facies configuration.These could be due to tectonic compression and plugging effect by rigid continental nucleus on the west margin of the Plate.Base on the above observations,we consider that the significant tectonic events at transition of Cambrian to Ordovician,which could be called and represented by Yunan orogeny,are well compared in South China and may provide new evidences on the initial time of tectonic—basin transition.