Optically stimulated luminescence dating of Ocean Drilling Program Core 658B : Complications arising from authigenic uranium uptake and lateral sediment movement. / Armitage, Simon.

In: Quaternary Geochronology, Vol. 30, No. Part B, 10.2015, p. 270-274.

Research output: Contribution to journalArticlepeer-review

Published

Standard

Optically stimulated luminescence dating of Ocean Drilling Program Core 658B : Complications arising from authigenic uranium uptake and lateral sediment movement. / Armitage, Simon.

In: Quaternary Geochronology, Vol. 30, No. Part B, 10.2015, p. 270-274.

Research output: Contribution to journalArticlepeer-review

Harvard

APA

Vancouver

Author

BibTeX

@article{5f52b714b8d54caf9ecd3912b4a8cec2,
title = "Optically stimulated luminescence dating of Ocean Drilling Program Core 658B: Complications arising from authigenic uranium uptake and lateral sediment movement",
abstract = "Ocean Drilling Program Site 658 lies under the North African summer dust plume, and ought to be an ideal target for optically stimulated luminescence (OSL) dating, since the main clastic input is far-travelled Saharan dust. However, OSL ages for coarse silt-sized quartz (40-63 µm) are systematically lower than independent age estimates when dose rates are calculated using a model which assumes detrital 238U, 232Th and 40K and excess 230Th and 231Pa. Ages which are in good agreement with independent age control are obtained from the coarse silt samples when a correction for authigenic uranium uptake is incorporated into the dose rate model. Authigenic uranium uptake occurs under reducing conditions, which are common at the sediment-water interface, and some degree of authigenic uranium correction may be required for most marine sediments. Using this revised dose rate model, ages produced using fine silt-sized quartz (4-11 µm) are up to 100% older than both independent and coarse silt ages. In addition, the fine silt ages show a consistent pattern of age decrease with depth over 1.5 m of core. 230Th data from Site 658 indicate that this site receives 3 times more sediment laterally than vertically. It is concluded that the fine silt at Site 658 contains a substantial reworked component, making it unsuitable for dating. Conversely the coarse silt fraction, which settles through water at ~40 times the rate of fine silt, appears to be derived from dust input over the site at the time of deposition. Since prominent nepheloid (cloudy) layers occur in various deep ocean basins, and the material suspended in these layers often consists of reworked fine silt-sized sediments, coarser material should be dated where possible.",
keywords = "Optically stimulated luminescence; Geochronology; Marine sediments; North Africa",
author = "Simon Armitage",
year = "2015",
month = oct,
doi = "10.1016/j.quageo.2015.03.002",
language = "English",
volume = "30",
pages = "270--274",
journal = "Quaternary Geochronology",
issn = "1871-1014",
publisher = "Elsevier",
number = "Part B",

}

RIS

TY - JOUR

T1 - Optically stimulated luminescence dating of Ocean Drilling Program Core 658B

T2 - Complications arising from authigenic uranium uptake and lateral sediment movement

AU - Armitage, Simon

PY - 2015/10

Y1 - 2015/10

N2 - Ocean Drilling Program Site 658 lies under the North African summer dust plume, and ought to be an ideal target for optically stimulated luminescence (OSL) dating, since the main clastic input is far-travelled Saharan dust. However, OSL ages for coarse silt-sized quartz (40-63 µm) are systematically lower than independent age estimates when dose rates are calculated using a model which assumes detrital 238U, 232Th and 40K and excess 230Th and 231Pa. Ages which are in good agreement with independent age control are obtained from the coarse silt samples when a correction for authigenic uranium uptake is incorporated into the dose rate model. Authigenic uranium uptake occurs under reducing conditions, which are common at the sediment-water interface, and some degree of authigenic uranium correction may be required for most marine sediments. Using this revised dose rate model, ages produced using fine silt-sized quartz (4-11 µm) are up to 100% older than both independent and coarse silt ages. In addition, the fine silt ages show a consistent pattern of age decrease with depth over 1.5 m of core. 230Th data from Site 658 indicate that this site receives 3 times more sediment laterally than vertically. It is concluded that the fine silt at Site 658 contains a substantial reworked component, making it unsuitable for dating. Conversely the coarse silt fraction, which settles through water at ~40 times the rate of fine silt, appears to be derived from dust input over the site at the time of deposition. Since prominent nepheloid (cloudy) layers occur in various deep ocean basins, and the material suspended in these layers often consists of reworked fine silt-sized sediments, coarser material should be dated where possible.

AB - Ocean Drilling Program Site 658 lies under the North African summer dust plume, and ought to be an ideal target for optically stimulated luminescence (OSL) dating, since the main clastic input is far-travelled Saharan dust. However, OSL ages for coarse silt-sized quartz (40-63 µm) are systematically lower than independent age estimates when dose rates are calculated using a model which assumes detrital 238U, 232Th and 40K and excess 230Th and 231Pa. Ages which are in good agreement with independent age control are obtained from the coarse silt samples when a correction for authigenic uranium uptake is incorporated into the dose rate model. Authigenic uranium uptake occurs under reducing conditions, which are common at the sediment-water interface, and some degree of authigenic uranium correction may be required for most marine sediments. Using this revised dose rate model, ages produced using fine silt-sized quartz (4-11 µm) are up to 100% older than both independent and coarse silt ages. In addition, the fine silt ages show a consistent pattern of age decrease with depth over 1.5 m of core. 230Th data from Site 658 indicate that this site receives 3 times more sediment laterally than vertically. It is concluded that the fine silt at Site 658 contains a substantial reworked component, making it unsuitable for dating. Conversely the coarse silt fraction, which settles through water at ~40 times the rate of fine silt, appears to be derived from dust input over the site at the time of deposition. Since prominent nepheloid (cloudy) layers occur in various deep ocean basins, and the material suspended in these layers often consists of reworked fine silt-sized sediments, coarser material should be dated where possible.

KW - Optically stimulated luminescence; Geochronology; Marine sediments; North Africa

UR - http://authors.elsevier.com/a/1S2y76fS6-BWd3

U2 - 10.1016/j.quageo.2015.03.002

DO - 10.1016/j.quageo.2015.03.002

M3 - Article

VL - 30

SP - 270

EP - 274

JO - Quaternary Geochronology

JF - Quaternary Geochronology

SN - 1871-1014

IS - Part B

ER -