期刊
QUATERNARY GEOCHRONOLOGY
卷 40, 期 -, 页码 45-55出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.quageo.2016.09.008
关键词
Sample preparation; Ice core; Microanalysis; Glass geochemistry; Tephrochronology; Cryptotephra
资金
- NSF Division of Polar Programs [PLR-1142115, 1142069, PLR-1142007, 1042883]
- Directorate For Geosciences
- Office of Polar Programs (OPP) [1142007] Funding Source: National Science Foundation
- Directorate For Geosciences
- Office of Polar Programs (OPP) [1142069, 1042883] Funding Source: National Science Foundation
Geochemical analysis of fine grained (<20 mu m) tephra found in ice cores is inherently difficult, due to the typically low number and small size of available particles. Ice core tephra samples require specialized sample preparation techniques to maximize the amount of information that can be gained from these logistically limited samples that may provide important chronology to an ice record, as well as linking glacial, marine and terrestrial sediments. We have developed a flexible workflow for preparation of tephra and cryptotephra samples to allow accurate and robust geochemical fingerprinting, which is fundamental to tephrochronology. The samples can be prepared so that secondary electron imagery can be obtained for morphological characterization of the samples to ensure that the sample is tephrabearing and then the sample can be further prepared for quantitative electron microprobe analysis using wavelength dispersive techniques (EMP-WDS), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), laser ablation inductively coupled mass spectrometry (LA-ICP-MS) or secondary ion mass spectrometry (SIMS). Some samples may be too small for typical instrumentation conditions to be used (i.e. 20 mu m beam on the EMP) to analyze for geochemistry and we present other techniques that can be employed to obtain accurate, although less precise, geochemistry. Methods include analyzing unpolished tephra shards less than 5 mu m in diameter with a 1 mu m beam on an SEM; using the broad beam overlap EMP method on irregular particles less than 20 mu m in diameter, and analyzing microlitic shards as well as aphyric shards using EMP to increase the number of analyzed shards in low abundance tephra layers. The methods presented are flexible enough to be employed in other geological environments (terrestrial, marine and glacial) which will help maximize and integrate multiple environments into the overall tephra framework. (C) 2016 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据