沉积物源区剥露历史分析的一种新途径——碎屑锆石和磷灰石裂变径迹热年代学

A NEW APPROACH TO DETERMINE THE EXHUMATION HISTORY OF THE SEDIMENT PROVENANCE∶DETRITAL ZIRCON AND APATITE FISSION-TRACK THERMOCHRONOLOGY

介绍了碎屑颗粒锆石和磷灰石裂变径迹年龄法的基本原理、应用前提及方法学。碎屑锆石和磷灰石裂变径迹颗粒年龄法的核心是通过逐一测定计算单颗粒裂变径迹年龄,然后将获得的一批单颗粒年龄进行高斯拟合或二项式拟合,获取其最佳的颗粒年龄分布,从而反演样品的不同源区的热历史。碎屑锆石和磷灰石因其在风化剥蚀搬运过程中具有较高的化学和物理稳定性而成为目前进行颗粒裂变径迹年龄分析中最常用的矿物类型,特别是碎屑锆石的裂变径迹密度大,单颗粒的裂变径迹具有可定年的统计意义,从而成为颗粒裂变径迹测年方法的首选矿物。

Using detrital zircon and apatite fissiontrack grain ages to determine the exhumation history of the sediment provenance has been developed in recent years. The key of this method is to utilize the fissiontrack ages of single detrital grains to identify and characterize the source area and also to quantify its thermochronological evolution. The steps can be summarized as:①dating fissiontrack ages grain by grain; ②looking for the grain age peaks and grainage populations by using Gaussian or binomial peakfitting;③identifying and characterizing the source area and quantifying the thermochronological evolution of the source area by analyzing the grainage populations. The most adaptable mineral to this method is detrital zircon because of its chemical and physical stability and its relatively high fissiontrack density. Detrital apatite is another mineral for this method. This paper introduces the principle, precondition and method of detrital zircon and apatite fissiontrack grain age dating.