Maximum depositional age estimation revisited
Maximum depositional age estimation revisited
复制标题
重新审视最大沉积年龄估计
DOI：
10.1016/j.gsf.2020.08.008
复制
发表时间：
2021
影响因子：
8.9
通讯作者：
Vermeesch P
中科院分区：
文献类型：
--
作者：
Vermeesch P
在最近发表在该杂志上的一篇综述中，Coutts等人（2019）比较了九种不同的方法，通过碎屑地质年代学来估计硅质岩石的最大沉积年龄（MDA）。结果表明，这些方法中有3种是正偏的，6种是负偏的。本文探讨了产生这些偏差的原因，并提出了解决方法。一个简单的玩具例子表明，即使在最好的情况下，从理论上讲，所审查的方法也不可能找到正确的沉积年龄：随着样本量的增加，MDA估计值会越来越小。这个问题可以用一个最大似然模型来解决，这个模型最初是由Galbraith和Laslett（1993）为裂变径迹热年代学开发的。这种方法用离散和连续分布的二元混合来参数化MDA估计问题。“最大似然年龄”（MLA）算法收敛到一个唯一的MDA值，与Coutts等人（2019）审查的临时方法不同。它成功地恢复了玩具样例的沉积年龄，并对实际分布产生了合理的结果。通过LA-ICPMS和CA-TIMS U-Pb地质年代学分析的13个砂岩样本数据集的应用说明了这一点。特设算法产生了不切实际的MDA估计，对于LA-ICPMS数据比CA-TIMS数据在系统上更年轻。MLA算法不会受到这种负偏差的影响。MLA方法是一种纯统计方法来估计MDA。与特别方法一样，它不容易适应地质复杂性，如沉积后的铅损失，或导致错误的年轻异常值的分析问题。在这种复杂的情况下，最好的方法是使用更精确的年代测定技术重新分析最年轻的谷物。MLA方法的结果在径向图上最直观。模型和图都有碎屑年代学以外的应用，例如确定火山喷发的年龄。
In a recent review published in this journal, Coutts et al. (2019) compared nine different ways to estimate the maximum depositional age (MDA) of siliclastic rocks by means of detrital geochronology. Their results show that among these methods three are positively and six negatively biased. This paper investigates the cause of these biases and proposes a solution to it. A simple toy example shows that it is theoretically impossible for the reviewed methods to find the correct depositional age in even a best case scenario: the MDA estimates drift to ever smaller values with increasing sample size. The issue can be solved using a maximum likelihood model that was originally developed for fission track thermochronology by Galbraith and Laslett (1993). This approach parameterises the MDA estimation problem with a binary mixture of discrete and continuous distributions. The ‘Maximum Likelihood Age’ (MLA) algorithm converges to a unique MDA value, unlike the ad hoc methods reviewed by Coutts et al. (2019). It successfully recovers the depositional age for the toy example, and produces sensible results for realistic distributions. This is illustrated with an application to a published dataset of 13 sandstone samples that were analysed by both LA-ICPMS and CA-TIMS U–Pb geochronology. The ad hoc algorithms produce unrealistic MDA estimates that are systematically younger for the LA-ICPMS data than for the CA-TIMS data. The MLA algorithm does not suffer from this negative bias. The MLA method is a purely statistical approach to MDA estimation. Like the ad hoc methods, it does not readily accommodate geological complications such as post-depositional Pb-loss, or analytical issues causing erroneously young outliers. The best approach in such complex cases is to re-analyse the youngest grains using more accurate dating techniques. The results of the MLA method are best visualised on radial plots. Both the model and the plots have applications outside detrital geochronology, for example to determine volcanic eruption ages.
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DOI：
--
发表时间：
1979
期刊：
影响因子：
--
作者：
D. Titterington;Alex N. Halliday
通讯作者：
Alex N. Halliday
影响因子：
12.1
作者：
P. Vermeesch
通讯作者：
P. Vermeesch
北美西部内陆盆地楔顶沉积带 Albian Wayan 组的稳定同位素古水文学和化学地层学
DOI：
--
发表时间：
2016
期刊：
Science China. Earth Sciences
影响因子：
--
作者：
Jeffrey B. Ross;G. Ludvigson;A. Möller;L. González;J. Walker
通讯作者：
J. Walker
影响因子：
5.3
作者：
Barbeau, David L., Jr.;Olivero, Eduardo B.;Gehrels, George E.
通讯作者：
Gehrels, George E.