Arid
DOI10.1016/j.quaint.2014.07.040
All mixed up: Using single-grain equivalent dose distributions to identify phases of pedogenic mixing on a dryland alluvial fan
Gliganic, L. A.; May, J. -H.; Cohen, T. J.
通讯作者Gliganic, L. A.
来源期刊QUATERNARY INTERNATIONAL
ISSN1040-6182
EISSN1873-4553
出版年2015
卷号362页码:23-33
英文摘要

The optically stimulated luminescence (OSL) signal from quartz grains is most often used to estimate the depositional age of sediments that were fully bleached during transport and have not been mixed after deposition. However, sediment that is transported fluvially may not have been exposed to sufficient sunlight to bleach the latent OSL signal, while stable land surfaces on which soils are developing will likely be subject to mixing processes such as pedoturbation. In these cases, large equivalent dose (De) datasets derived from individual sand-sized quartz grains can shed light on the depositional and post-depositional histories of sedimentary deposits. Here, we report the results of geochronological investigations of Mt Chambers Creek alluvial fan, on the eastern footslopes of the Flinders Ranges, South Australia. We collected 13 OSL samples from bank exposures and pits excavated into relict floodouts to reconstruct late Quaternary alluvial dynamics. Single-grain D-e datasets yielded overdispersion-values of between 26 and 68%. Most of these values are significantly higher than the overdispersion values obtained during dose-recovery experiments, suggesting that many deposits were poorly bleached, mixed, and/or experienced significant dose rate heterogeneity. Single-grain measurements of a sample from the modern floodout demonstrate that partial bleaching is minor and cannot explain the D-e distributions for Holocene and Pleistocene samples. The results of systematic application of the finite mixture model (FMM) to all D-e datasets in conjunction with contextual observations suggest that post-depositional mixing by pedoturbation has significantly affected the deposits and observed OSL data. For most samples, we infer that the most populous FMM component represents deposition and that secondary components represent intrusive younger grains or partially bleached older grains. The fan-wide presence of contemporaneous intrusive grain-populations suggests that post-depositional mixing occurred in phases, possibly associated with intervals of increased pedoturbation. (C) 2014 Elsevier Ltd and INQUA. All rights reserved.


英文关键词Post-depositional mixing Finite mixture model Soils Pedogenesis Pedoturbation Optically stimulated luminescence
类型Article
语种英语
国家Australia
收录类别SCI-E
WOS记录号WOS:000350998100005
WOS关键词OPTICALLY STIMULATED LUMINESCENCE ; JINMIUM ROCK SHELTER ; SOUTH-AFRICA ; NORTHERN AUSTRALIA ; MULTIPLE GRAINS ; ARID AUSTRALIA ; QUARTZ GRAINS ; DEPOSITS ; SEDIMENTS ; SOIL
WOS类目Geography, Physical ; Geosciences, Multidisciplinary
WOS研究方向Physical Geography ; Geology
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/189990
作者单位Univ Wollongong, Sch Earth & Environm Sci, GeoQuEST Res Ctr, Wollongong, NSW 2500, Australia
推荐引用方式
GB/T 7714
Gliganic, L. A.,May, J. -H.,Cohen, T. J.. All mixed up: Using single-grain equivalent dose distributions to identify phases of pedogenic mixing on a dryland alluvial fan[J],2015,362:23-33.
APA Gliganic, L. A.,May, J. -H.,&Cohen, T. J..(2015).All mixed up: Using single-grain equivalent dose distributions to identify phases of pedogenic mixing on a dryland alluvial fan.QUATERNARY INTERNATIONAL,362,23-33.
MLA Gliganic, L. A.,et al."All mixed up: Using single-grain equivalent dose distributions to identify phases of pedogenic mixing on a dryland alluvial fan".QUATERNARY INTERNATIONAL 362(2015):23-33.
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