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Kristina Jørkov Thomsen

Bio: Kristina Jørkov Thomsen is an academic researcher from Technical University of Denmark. The author has contributed to research in topics: Optically stimulated luminescence & Thermoluminescence dating. The author has an hindex of 34, co-authored 82 publications receiving 4434 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors determined fading rates for various sedimentary feldspar samples using different stimulation and detection windows, and found that the initial and final parts of the OSL signal bleach at approximately the same rate.

641 citations

Journal ArticleDOI
01 Jul 2012-Boreas
TL;DR: In this paper, the authors proposed a post-IR IRSL (IRSL) method for the dating of Middle and Late Pleistocene sediments, which appears to avoid signal instability.
Abstract: Luminescence dating is used extensively to provide absolute chronologies for Late Pleistocene sediments. Nowadays, most optical dates are based on quartz optically stimulated luminescence (OSL). However, the application of this signal is usually limited to the last ∼100 ka because of saturation of the quartz luminescence signal with dose. In contrast, the feldspar infrared stimulated luminescence (IRSL) dose–response curve grows to much higher doses; this has the potential to extend the datable age range by a factor of 4–5 compared with quartz OSL. However, it has been known for several decades that this IRSL signal is unstable, and this instability often gives rise to significant age underestimation. Here we test against independent age control the recently developed feldspar post-IR IRSL approach to the dating of sediments, which appears to avoid signal instability. A physical model explaining our observations is discussed, and the method is shown to be accurate back to 600 ka. The post-IR IRSL signal is reduced by exposure to daylight more slowly than that from quartz and low-temperature IRSL, preventing its general application to young (e.g. Holocene) sediments. Nevertheless, this new approach is widely applicable (feldspar of appropriate luminescence behaviour is even more ubiquitous than quartz). These characteristics make this a method of great importance for the dating of Middle and Late Pleistocene deposits.

573 citations

Journal ArticleDOI
TL;DR: Thomsen et al. as mentioned in this paper proposed a post-IR IR dating protocol on K-feldspar extracts from a variety of locations and depositional environments and compare the results with those from the conventional IR at 50°C protocol.

521 citations

Journal ArticleDOI
TL;DR: In this paper, a review describes 40 years of experience gained at Riso National Laboratory in the development of facilities for irradiation, thermal/optical stimulation and luminescence signal detection.

279 citations

Journal ArticleDOI
TL;DR: In this article, the difference in relative bleaching rates of quartz optically stimulated luminescence (OSL) and feldspar residual signals after natural bleaching prior to deposition was investigated for identifying well-bleached quartz samples.

231 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the effects of optically stimulated luminescence (OSL) components, other than that usually termed the fast component, on dose determination by the single-aliquot regenerative-dose (SAR) protocol are examined.

1,856 citations

Journal ArticleDOI
TL;DR: In this article, the authors determined fading rates for various sedimentary feldspar samples using different stimulation and detection windows, and found that the initial and final parts of the OSL signal bleach at approximately the same rate.

641 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a synthesis of the literature on the 32 biggest rivers in the world and propose a governance framework to monitor these rivers, finance their continual upkeep and help ameliorate increasing anthropogenic pressures, including large-scale damming, hydrological change, pollution, introduction of non-native species and sediment mining.
Abstract: The world’s big rivers and their floodplains were central to development of civilization and are now home to c. 2.7 billion people. They are economically vital whilst also constituting some of the most diverse habitats on Earth. However, a number of anthropogenic stressors, including large-scale damming, hydrological change, pollution, introduction of non-native species and sediment mining, challenge their integrity and future, as never before. The rapidity and extent of such change is so great that large-scale, and potentially irreparable, transformations may ensue in periods of years to decades, with ecosystem collapse being possible in some big rivers. Prioritizing the fate of the world’s great river corridors on an international political stage is imperative. Future sustainable management, and establishment of environmental flow requirements for the world’s big rivers, must be supported through co-ordinated international funding, and trans-continental political agreement to monitor these rivers, finance their continual upkeep and help ameliorate increasing anthropogenic pressures. To have any effect, all of these must be set within an inclusive governance framework across scales, organizations and local populace. Stressors such as large-scale damming, hydrological change, pollution, the introduction of non-native species and sediment mining are challenging the integrity and future of large rivers, according to a synthesis of the literature on the 32 biggest rivers.

598 citations

Journal ArticleDOI
01 Jul 2012-Boreas
TL;DR: In this paper, the authors proposed a post-IR IRSL (IRSL) method for the dating of Middle and Late Pleistocene sediments, which appears to avoid signal instability.
Abstract: Luminescence dating is used extensively to provide absolute chronologies for Late Pleistocene sediments. Nowadays, most optical dates are based on quartz optically stimulated luminescence (OSL). However, the application of this signal is usually limited to the last ∼100 ka because of saturation of the quartz luminescence signal with dose. In contrast, the feldspar infrared stimulated luminescence (IRSL) dose–response curve grows to much higher doses; this has the potential to extend the datable age range by a factor of 4–5 compared with quartz OSL. However, it has been known for several decades that this IRSL signal is unstable, and this instability often gives rise to significant age underestimation. Here we test against independent age control the recently developed feldspar post-IR IRSL approach to the dating of sediments, which appears to avoid signal instability. A physical model explaining our observations is discussed, and the method is shown to be accurate back to 600 ka. The post-IR IRSL signal is reduced by exposure to daylight more slowly than that from quartz and low-temperature IRSL, preventing its general application to young (e.g. Holocene) sediments. Nevertheless, this new approach is widely applicable (feldspar of appropriate luminescence behaviour is even more ubiquitous than quartz). These characteristics make this a method of great importance for the dating of Middle and Late Pleistocene deposits.

573 citations

Journal ArticleDOI
TL;DR: Thomsen et al. as mentioned in this paper proposed a post-IR IR dating protocol on K-feldspar extracts from a variety of locations and depositional environments and compare the results with those from the conventional IR at 50°C protocol.

521 citations