广西东攀二叠系-三叠系界线剖面基于岩石磁参数的米兰科维奇旋回特征和地层对比  

CYCLOSTRATIGRAPHY AND STRATIGRAPHIC CORRELATION BASED ON ROCK-MAGNETIC PARAMETERS ON THE PERMIAN-TRIASSIC BOUNDARY IN THE DONGPAN SECTION IN GUANGXI

作　　者：陈建业[1] 冯庆来[1] 陈晶[1] 朱宗敏[1] 

机构地区：[1]中国地质大学生物地质与环境地质教育部重点实验室,湖北武汉430074

出　　处：《地层学杂志》2007年第4期309-316,共8页Journal of Stratigraphy

基　　金：国家自然科学基金(No40232025);国家理科基础科学研究和教学人才培养基地资金资助

摘　　要：二叠纪-三叠纪之交发生了地质历史上最大的生物集群绝灭。通过对广西东攀二叠系-三叠系界线剖面不同的磁学数据进行频谱分析,其结果均具一致的功率谱峰,对比煤山剖面的同位素年龄将厚度频率35.7∶15.6∶7.7cm/cycle换算为时间周期95∶41.6∶20.5kyr/cycle,分别与米兰科维奇旋回偏心率、斜度、岁差相当,从而将地层研究的精度提高到万年级,为生物绝灭和众多地质事件提供时间上的约束。不同的磁学参数分别受控于不同的天文周期,磁性矿物种类主要受偏心率旋回控制,同时也受斜度周期的影响,而岁差周期则是促使岩石携磁能力高频变化的原因。不同二叠系—三叠系剖面(集中在界线附近)的磁化率曲线具有一致特征,可作为界线点确定的辅助依据。The Permian-Triassic boundary is marked by the most severe mass extinction in the geologic re- cord. Frequency analysis of different magnetic parameters on the Permian-Triassic boundary section in Dongpan, Guangxi shows consistent power spectral peaks. Correlation with the dated Meishan section shows that the stratigraphic thickness cycles （35.7：15.6：7.7 cm/cycle） can be translated into temporal periods （95：41.6：20.5 kyr）.. These cycles are identified as Milankovitch cycles （eccentricity, obliquity, precession）, and they significantly enhance the resolution for stratigraphic correlation to 104 yrs and pro- vide temporal constraint on faunal extinction and other catastrophic events. Cycles of different magnetic parameters are controlled by different orbit periods： magnetic minerals are mainly controlled by eccentrici- ty and partially by obliquity, whereas precession period is the cause for high-frequency fluctuation of rock magnetic competence. Susceptibility curves at the Permian-Triassic boundary at different sections have a consistent pattern which could assist us recognizing stratigraphic boundaries.

关 键 词：磁化率 米兰科维奇旋回 地层对比 二叠纪-三叠纪界线 东攀剖面 广西 

分 类 号：P618.130.1[天文地球—矿床学]