1. Approaching Last Glacial Maximum to Holocene continental surface air temperature reconstruction using thermoluminescence paleothermometry.
- Author
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Oehler, Salome, Niyonzima, Pontien, Herman, Frédéric, King, Georgina, and Schmidt, Christoph
- Subjects
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LAST Glacial Maximum , *PALEOTHERMOMETRY , *SURFACE temperature , *ATMOSPHERIC temperature , *THERMOLUMINESCENCE , *HUMAN comfort , *COINCIDENCE - Abstract
Thermoluminescence (TL) paleothermometry enables direct determination of past rock surface temperatures. For this, it exploits the dependence of electron de-trapping on ambient temperatures over geological timescales. It focuses on trapping energies connected to shorter lifetimes and lower-temperature signals (i.e. TL signals in the ~180-250 °C range of quartz and feldspar) that are typically disregarded during dating applications. The use of feldspar is particularly promising due to the continuous distribution of trapping energies and thus paleothermometers. Recent methodological advances [1] have made it feasible to explore the possibility of worldwide continental rock surface temperature reconstruction. This allows for headway to be made in closing the knowledge gap of continental air temperatures during the Last Glacial Maximum (LGM) and Pleistocene-Holocene transition. Our ultimate objective is to test the applicability of TL paleothermometry by studying sites from Scandinavia to equatorial east Africa, aiming to provide LGM to Holocene surface temperature fluctuations for a meridional gradient of approximately 7000 km length. In addition, we have recently sampled two altitudinal gradients for the Mont Blanc Massif (France) and Rwenzori Mountains (Uganda) to constrain changes in the atmospheric lapse rate since the LGM. Such data are critical in testing climate models and inferring the dynamics in atmospheric circulation across glacial-interglacial cycles. This contribution presents the methodology and associated analytical steps of TL paleothermometry by relaying first results of kinetic parameter determination and dose response characterisation for samples from the Mont Blanc Massif. In addition, we address one of the main methodological challenges of the TL paleothermometry method: the inherent temperature offset between the reconstructed rock surface temperatures and respective past surface air temperatures. To overcome this challenge, reliable offset correction related to site-specific factors such as aspect, elevation and potential incoming solar irradiation is required. We thus conclude our contribution with discussing the potential of the method and future methodological work (e.g., temperature offset correction and definition of saturation levels for various quartz and feldspar signals) required to establish the TL paleothermometry method. [ABSTRACT FROM AUTHOR]
- Published
- 2023