摘要
锶同位素地层学是海相地层定年和全球对比的有效工具。为了建立全球范围的w(87Sr)/w(86Sr)比值年龄数据库,就必须对大量的w(87Sr)/w(86Sr)比值年龄数据进行拟合,寻找最佳方法用于缩小最佳拟合曲线的区间范围是目前锶同位素地层学所面临的难题之一。在各种统计与拟合方法中,LOWESS(局部加权回归散点修匀法)为研究计算全球标准锶曲线最佳拟合模式提供了一种非参数拟合的精妙方法,拟合得出的最佳曲线能较好地作为海相地层的定年和进行全球对比的基础数据,并具有较高的置信区间。
As an essential tool,the Strontium Isotope Stratigraphy(SIS)can be used to date and correlate marine sediments.Many geological events can be explained with the Global Standard Strontium Curve(GSSC),which representing the evolution of marine w(^(87)Sr)/(w(^(86)Sr)) through numerical times.The GSSC has highly important theoretical direction and rea工l application in dating and correlating marine sediments.Therefore,the isotopic stratigraphers are trying to find out the optimum manner to shorten the section dimension of the best fitting curve.According to the position of w(^(87)Sr)/(w(^(86)Sr)) on GSSC,we will assign the unknown estimation to numerical age.Compared with the measured value of w(^(87)Sr)/(w(^(86)Sr)),we can also gather all influence factors.LOWESS fit on statistics provides a shrewd manner to research and figure the optimum fitting mode of GSSC.When assigning numerical ages to sediments or estimating the duration of a biozone or a hiatus in sedimentation,the task is made both easier and less prone to error by using the LOWESS fit curve,which allows quick and easy conversion from w(^(87)Sr)/(w(^(86)Sr)) to numerical age.It is clear that a great deal of improvement needs to be made to most of the Phanerozoic (w(^(87)Sr)/(w(^(86)Sr)) )curve if SIS is to realize its true potential for dating and correlating rocks.
出处
《地球科学与环境学报》
CAS
2004年第2期1-5,共5页
Journal of Earth Sciences and Environment
基金
国家自然科学基金项目(40272059)
国家基础研究重大项目(2001CCA01800)
