摘要
二叠纪—三叠纪之交,海洋和陆地均经历了地球历史上最严重的生物危机,大灭绝事件前后沉积环境的恢复及古气候的重建是生物大灭绝事件研究的基础。济源盆地位于华北板块南缘,二叠纪—三叠纪陆相地层发育完整且接触清晰,是研究华北板块二叠纪—三叠纪之交古气候和沉积环境演化的良好区域。以豫西济源大峪镇剖面孙家沟组为研究对象,综合运用岩石学、沉积学、古生物学和地球化学方法对研究区进行了系统研究。结果表明:济源孙家沟组从下部曲流河环境逐渐过渡为滨湖环境。孙家沟组下、中段地化数据表明当时的年降水量较低,古温度与化学风化强度较高,反映了干旱—半干旱为主的气候特征,可能为全球性巨型季风影响的结果,并由此导致了“济源动物群”的消失和微生物成因沉积构造(MISS)的发育。中段沉积期末期气候向湿润转变,到上段顶部干旱气候再次占据主导地位并持续至早三叠世。整体上,孙家沟组沉积期呈湿润—干旱—半湿润—干旱的气候变化,干旱炎热的气候可能是研究区陆地生态环境遭到破坏的重要原因,环境的退化加剧了陆相生物灭绝;根据岩性特征、古气候、古环境、MISS等,综合推测P-T之交灭绝事件发生在孙家沟组沉积期早期。
Both the ocean and the land experienced the most severe biological crisis during the Permian⁃Triassic tran⁃sition.Restoration of the sedimentary environment and reconstruction of the paleoclimate before and after the mass ex⁃tinction event lay the foundation of this study.The study area in the Jiyuan Basin is located at the southern margin of the North China Plate,where the Permian⁃Triassic terrestrial strata are well developed and the contact is clear.The methods of petrology,sedimentology,paleontology and geochemistry were used to study the Dayu Section of the Sun⁃jiagou Formation,situated near Jiyuan city,western Henan province.The succession from the lower strata record a gradual change from a meandering stream environment to a lacustrine shore environment.Geochemical data from the lower and middle strata show low annual precipitation,increasing temperatures and enhanced chemical weathering,and reflect an arid to semi-arid climate,possibly arising from the global giant monsoon.Deposits from this unusual pe⁃riod are characterized by the disappearance of Jiyuan fauna and the emergence of microbially induced sedimentary structures(MISS).The climate tended to become humid for a short time at the end of the middle depositional period,then a persistent arid climate dominated until the Lower Triassic,as evidenced from the upper strata.On the whole,the Sunjiagou Formation reflects a transformation from a humid-arid to a subhumid-arid climate during the sedimenta⁃tion period.The dry and hot climate may have been an important factor in the destruction of terrestrial ecosystems,leading to the extinction of terrestrial organisms.The lithological evidence,paleoclimate and flourishing MISS in the middle strata indicate that the Permian⁃Triassic mass extinction(PTME)possibly occurred during the early sedimen⁃tary stage of the Sunjiagou Formation.
作者
郑伟
许欣
齐永安
邢智峰
刘云龙
李婉颖
吴盼盼
张湘赟
ZHENG Wei;XU Xin;QI YongAn;XING ZhiFeng;LIU YunLong;LI WanYing;WU PanPan;ZHANG XiangYun(Institute of Resource and Environment,Henan Polytechnic University,Jiaozuo,Henan 454003,China;Key Laboratory of Biogenetic Traces&Sedimentary Minerals of Henan Province,Jiaozuo,Henan 454003,China;Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region,Henan Province,Jiaozuo,Henan 454003,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2023年第2期392-408,共17页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(41772110)
河南省高等学校重点科研项目(20A170010)。
