古地理学报2012，Vol.14Issue(1)：101-116,16.
浙西北上奥陶统文昌组和堰口组沉积特征及其意义
Sedimentary characteristics of the Upper Ordovician Wenchang and Yankou Formations in northwestern Zhejiang Province
摘要
Abstract
Based on new collections of fossils from the Upper Ordovician Wenchang, Yankou and Anji Formations in northwestern Zhejiang Province, southeastern China, especially those significant grap-tolites, the Wenchang Formation is considered to be equivalent to the Yankou Formation, and is largely of Hirnantian Age. In Hirnantian Age, the Gondwana ice sheet, centered in the North Africa, reached its maximum, as evidenced by that more and more glacial deposits (tillites or diamictites) of the age have been reported across the world. The Wenchang and Yankou Formations yield well-developed conglomer-ates, which are unique in South China and might be related with the glaciation event. Regarding the origination of the conglomerates, there have been some debates and viewpoints from different perspectives. Based on sedimentary studies, these conglomerates display different sedimentary characters and mechanisms among localities and sections in the region. They represent several types of channel depositions in shallow water. A detailed regional lithofacies study of the Wenchang and Yankou Formations in northwestern Zhejiang Province indicates that a Zhe-Wan Basin was developed in the Hirnantian Age, with Cathay-sian Land located to its southeast and served as the clastic source. The basin becomes deeper northwestwardly, following the palaeogeographic pattern of pre-Hirnantian. Petrological analysis of the sandstones in the Wenchang and Yankou Formations displays a low compositional maturity along with a low textural maturity, and a provenance of recycled orogenic belt, which indicate a probable sustaining uplift of the Cathaysian Land. The regressional sequence recognized in the Wenchang and Yankou Formations in northwestern Zhejiang Province can be well correlated with that of other continents or regions, such as North Africa, Middle East, U. K. ,Sweden and Czech etc.关键词
砾岩层/冰川/文昌组/堰口组/赫南特期/奥陶纪/浙西北Key words
conglomerate/ glaciation/ Wenchang Formation/ Yankou Formation/ Hirnantian Age/Ordovician/ northwestern Zhejiang Province分类
天文与地球科学引用本文复制引用
刘晓,张元动,周传明..浙西北上奥陶统文昌组和堰口组沉积特征及其意义[J].古地理学报,2012,14(1):101-116,16.基金项目
中科院知识创新工程方向性项目(编号:KZCX2-YM-122)和国家自然科学基金项目(编号:40532009)共同资助 （编号:KZCX2-YM-122）
