Quartz age extension applied to SE Asian cover sands
Quartz age extension applied to SE Asian cover sands
A significant feature of the surface sediments of southeast Asia is a regionally extensive layer of distinctive red, quartz-rich, cover sand observed throughout Vietnam, Cambodia, Laos and Thailand, and further afield. In many locations, these cover sands immediately overlay a laterite layer containing tektites, known as the Muong Nong type, associated with a large meteorite impact between 750 and 800ka in Indochina. Sections of these cover sands at sites in Thailand, Laos and Vietnam have been investigated using field and laboratory profiling, and quartz SAR procedures. In some locations the sections consist of a layer of low-sensitivity quartz with saturated signals overlain by a visibly indistinguishable layer of high-sensitivity quartz with ages less than c. 35ka. Further work has been undertaken to attempt to extend quartz luminescence dating for the older materials, including samples associated with the tektites, using thermally stimulated or transferred luminescence to access traps that are expected to saturate at higher doses. Luminescence was recorded during sample heating and hold, giving thermoluminescence (TL-ramp) and isothermal decay (ID) data, in addition to optically stimulated luminescence after the transfer (Thermally Transferred Optically Stimulated Luminescence, TT-OSL) measurements. These measurements have produced equivalent dose values of up to 250Gy, and ages of 70–125ka, for these older materials, which is significantly younger than would be expected from the association with the tektites. Investigation of the traps associated with these signals has produced properties consistent with prior investigations, suggesting that these are not sufficiently stable at environmental temperatures above 25 °C to permit age extension using these methods.
isothermal decay, thermally transferred optically stimulated luminescence, thermoluminescence
Cresswell, A.J.
530695b9-32da-4611-87be-8029da26e3a9
Sanderson, D.C.W.
0b0d953c-d5c8-4186-85ec-ca6f60bb041a
Carling, P.A.
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Darby, S.E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
17 March 2022
Cresswell, A.J.
530695b9-32da-4611-87be-8029da26e3a9
Sanderson, D.C.W.
0b0d953c-d5c8-4186-85ec-ca6f60bb041a
Carling, P.A.
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Darby, S.E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Cresswell, A.J., Sanderson, D.C.W., Carling, P.A. and Darby, S.E.
(2022)
Quartz age extension applied to SE Asian cover sands.
Quaternary Geochronology, 69, [101271].
(doi:10.1016/j.quageo.2022.101271).
Abstract
A significant feature of the surface sediments of southeast Asia is a regionally extensive layer of distinctive red, quartz-rich, cover sand observed throughout Vietnam, Cambodia, Laos and Thailand, and further afield. In many locations, these cover sands immediately overlay a laterite layer containing tektites, known as the Muong Nong type, associated with a large meteorite impact between 750 and 800ka in Indochina. Sections of these cover sands at sites in Thailand, Laos and Vietnam have been investigated using field and laboratory profiling, and quartz SAR procedures. In some locations the sections consist of a layer of low-sensitivity quartz with saturated signals overlain by a visibly indistinguishable layer of high-sensitivity quartz with ages less than c. 35ka. Further work has been undertaken to attempt to extend quartz luminescence dating for the older materials, including samples associated with the tektites, using thermally stimulated or transferred luminescence to access traps that are expected to saturate at higher doses. Luminescence was recorded during sample heating and hold, giving thermoluminescence (TL-ramp) and isothermal decay (ID) data, in addition to optically stimulated luminescence after the transfer (Thermally Transferred Optically Stimulated Luminescence, TT-OSL) measurements. These measurements have produced equivalent dose values of up to 250Gy, and ages of 70–125ka, for these older materials, which is significantly younger than would be expected from the association with the tektites. Investigation of the traps associated with these signals has produced properties consistent with prior investigations, suggesting that these are not sufficiently stable at environmental temperatures above 25 °C to permit age extension using these methods.
More information
Accepted/In Press date: 15 March 2022
e-pub ahead of print date: 17 March 2022
Published date: 17 March 2022
Additional Information:
Funding Information:
Carling benefited from a Leverhulme Emeritus Fellowship (2016–2018) and from support in the field provided by Prof. R. Tada (Japan Society for the Promotion of Science (JSPS) KAKENHI Fostering Joint International Research (B) 18KK0092 (2018–2021)). The luminescence analyses were part funded by the Biotechnology and Biological Sciences Research Council under a Global Challenges Research Fund Foundation Award for Global Agriculture and Food Systems Research (BB/P022693/1) awarded to Darby.
Keywords:
isothermal decay, thermally transferred optically stimulated luminescence, thermoluminescence
Identifiers
Local EPrints ID: 456104
URI: http://eprints.soton.ac.uk/id/eprint/456104
ISSN: 1871-1014
PURE UUID: dd15e16e-8470-457b-bc32-3eb7403ee2ad
Catalogue record
Date deposited: 26 Apr 2022 14:50
Last modified: 17 Mar 2024 02:46
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Contributors
Author:
A.J. Cresswell
Author:
D.C.W. Sanderson
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