浙江衢州硅化木埋藏时限及生态环境分析

BURIAL TIME CONSTRAIN AND ECOLOGICAL ENVIRONMENT ANALYSIS OF THE SILICIFIED WOOD IN QUZHOU, ZHEJIANG

通过对衢州石梁-横山一带硅化木出露点的调查,在查明其赋存地层的岩性岩相、原木种属和形成时限的基础上,对其生长环境、硅化地质因素进行了分析。衢州发现的硅化木赋存于下白垩统劳村组地层中,所赋层岩石经SHRIMP锆石U-Pb测年,结果为133±2 Ma和138.1±2.3 Ma。原木为松柏类南洋杉型木种属,生长于亚热带温湿气候的盆地边缘河湖环境中,但生态环境不稳定,多洪水及火山喷发。原木在火山-沉积作用中被迅速埋藏,区域上常山-漓渚断裂带活动引发的火山作用为原木后期硅化提供了热源和硅源。

Through the investigation of the fossil site of the silicified wood in Shiliang-Hengshan, Quzhou, the growth environment and silicification process were analyzed on the basis of the lithologic facies, the original plant of the wood fossils and the dating. The silicified woods were found in the Lower Cretaceous Laocun Formation in Quzhou area according to the SHRIMP zircon U-Pb ages of 133±2 Ma and 138.1±2.3 Ma. The woods belonged to Araucarioxylon sp., a species of conifer, which grew on the edge of river with a temperate and wet climate in the subtropics. But the ecological environment was unstable and there were many floods and volcanic eruptions. Woods were quickly buried in volcano-sedimentation process. The volcanism caused by the activities of the Changshan-Lizhu fault in the region provided a source of heat and silicon for the later silicification of the woods.