摘要
利用小波分析技术,对采集自四川广元上寺剖面上二叠统—下三叠统格里斯巴赫亚阶以碳酸盐岩为主的沉积序列的自然伽马(GR)能谱序列进行深入分析研究,结果表明,该沉积序列很大程度上受到410:102.5:42.6:21.5的米兰科维奇旋回控制。晚二叠世上寺剖面位于古特提斯洋的深水环境,沉积速率较低,平均为5cm/ka;二叠纪—三叠纪过渡时期研究区构造活动强烈,陆地及海洋生物发生大灭绝,由于酸雨以及植被缺乏等气候及生态因素影响,陆地表面风化速率急剧增加,大量陆源物质注入导致早三叠世早期浅海系统沉积速率提高至25cm/ka,并强烈影响了海洋生态系统,抑制了海洋生物的多样性,延缓了海洋生态复苏进程。在二叠纪末期,上寺剖面沉积记录的旋回性较为明显且稳定,到三叠纪早期旋回性有所变差。早三叠世沉积速率的显著变化和旋回性差异与该时期动荡的古气候、古海洋环境密切相关,地球表层环境变化对海洋生态系统具有较强的影响,且可能成为早三叠世海洋生态系统复苏缓慢的主要控制因素之一。
Based on the analysis of the GR energy spectrum collected from the Upper Permian to Lower Triassic carbonate rocks in Shangsi section at Guangyuan area,Sichuan Province,it was indicated that the sedimentary layers are controlled by Milankovitch cycles,whose scale ratio was 410：102.5：42.6：21.5.During the Late Permian,the Shangsi area was in a deep-water environment of the paleo-Tethys and the deposition rate was low to 5 cm/ka.During the P-T transitional period the tectonic movement was strong and terrestrial and marine fauna experienced mass extinction.At the same time,weathering rate increased sharply because of the acid rain and lack of terrestrial vegetation and mass terrigenous material fluxed into shallow sea in turn,which resulted in a rapid deposition rate of 25 cm/ka in Shangsi section.The rapid rate of deposition displayed a strong influence on marine ecosystems,that is,it restrained the diversity of marine fauna and delayed the resuscitating of marine ecosystems.The cyclicity of the latest Permian sedimentary record was more obvious and stable in Shangsi section.However,the periodicity turned to be labile when it came to the Early Triassic.We concluded that the accelerated deposition rate and deteriorated sedimentary cyclicity were triggered by the turbulent paleoclimate and mussy marine environment.The perturbation of the terrestrial realm contributed to the change of marine conditions,which might be one of the major reasons for the marine ecosystem recovering relatively slowly in the Early Triassic.
出处
《古地理学报》
CAS
CSCD
北大核心
2012年第3期403-410,共8页
Journal of Palaeogeography：Chinese Edition
基金
国家自然科学基金项目(编号:40872082)资助
