基于核密度估计的碎屑颗粒年龄分析及应用:松辽盆地构造事件定年  

Decomposition the detrital grain ages by Kernel Density Estimation and its applications:Determining the major tectonic events in the Songliao Basin,NE China

作　　者：宋鹰 张俊霞[2] Andrei Stepashko 袁万明[4] 丛旭日[5] 

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [2]中国地质大学(武汉)经管学院,湖北武汉430074 [3]俄罗斯科学院大地构造与地球物理研究所,俄罗斯哈巴罗夫斯克680000 [4]中国地质大学(北京)科学研究院,北京100083 [5]青岛大学数学系,山东青岛266071

出　　处：《地学前缘》2016年第4期265-276,共12页Earth Science Frontiers

基　　金：国家自然科学基金项目(41402171);国家科技重大专项(2011ZX05009-001);山东省自然科学基金项目(ZR2013DQ013);中央高校基本科研业务费专项(16CX02038A)

摘　　要：碎屑矿物热年代学是了解板块碰撞、造山带抬升剥露以及盆地沉积等地质事件的重要途径之一。同一沉积区内碎屑颗粒通常是多来源的,含有不同的年龄组分,如何获得真实的年龄组分分布样式,进而准确地提取出地质年龄信息是碎屑颗粒年龄分析的关键。由于受到数学原理、组距选择和样品分析测试误差等因素的影响,常用的地质年龄频率分布图和概率密度曲线难以得到真实的年龄分布样式。本文引入一种新的同位素年龄数据统计方法——核密度估计法。该方法以同位素年龄数据为基础,根据数据密度和测试误差自适应变换带宽函数,减少了测试误差和样本数量的干扰,有效地提高了年龄分解精度。该方法尤其适用于同位素年龄样本数量少的研究新区以及测试误差大的碎屑颗粒年代学数据分析。本文应用核密度估计法,对大兴安岭地区显生宙花岗岩锆石U-Pb年龄数据库和松辽盆地碎屑磷灰石裂变径迹年龄数据进行了分析,所得到的年龄分布样式不但与区域地质背景、盆地构造-沉积记录等地质事实相吻合,还进一步准确约束了区域构造事件的年代界限。因此核密度估计法是一种能合理有效地进行地质年龄分布样式分析的先进统计方法。The thermochronology of detrital grains has quickly become a very popular technique for understanding some complicated geological processes,e.g.plate collision,orogeny and sedimentary provenance studies.Detrital single grains from well-dated sedimentary formations contain different age components,serving as mineral tracers in sedimentary systems and record the sediment-forming processes.Therefore how to decompose and visualize the ages faithfully and extract possible geological information are keys to the understanding thermochronology result of detrital grains.Binned Frequency Estimation and Probability Density Estimation are two extensively using approaches.Unfortunately,both of them lack a firm theoretical basis and can produce inaccurate results when data quantity or quality is low.This paper introduces a statistical technique for analyzing isotope age,called Kernel Density Estimation（KDE）,which involves the age data,but explicitly takes into account the analytical uncertainties by inherent adaptive bandwidth functions.Such adaptive functions vary the bandwidth according to the local density,avoiding the uncertainties from analytical errors and age abundance.Finally,we used the KDE to study two independent thermochronology date sets in northeast China：the zircon U-Pb ages of Phanerozoic granitoids in Great Xing＇an Range and the single grain fission track ages of detrital apatite in the Songliao Basin.The estimated age pattern coincides with the regional tectonics and tectono-sedimentary records in the study area.It also gives more accurate chronological constraints to some major regional tectonic events.Thus,the KDE proves to be a valid statistical approach for geologic age decomposition.

关 键 词：碎屑颗粒 热年代学 核密度估计 松辽盆地 构造热演化史 

分 类 号：P588.21[天文地球—岩石学]