Shining new light on environmental analysis Loess deposits cover about 10 percent of the earth’s land surface, and are an important resource in reconstructing palaeoclimate. We spoke to Dr Alida Timar-Gabor about the INTERTRAP project’s work in investigating and analysing loess samples from three different continents, with the aim of developing improved dating methods Many large deposits of loess can be found across the world, covering around 10 percent of the earth’s land surface and providing a rich source of data for scientists to investigate the development and evolution of the global climate over time. Loess itself is essentially a type of windblow dust, samples of which Dr Alida TimarGabor and her colleagues in the Intertrap project have been analysing in great detail. “We have been working on dating the loess-palaeosol deposits in Eastern Europe for some time. Now we will extend our work and date loess-palaeosol deposits in China, Europe, and the US,” she outlines. These loess-palaeosoil sequences represent important archives of past climate, from which scientists can draw new insights.
Luminescence and sedimentology sample collection from loess (Loveland, Iowa).
“They basically represent a succession of changes between glacial and warm past climate. So when we have a warm period, like the Holocene period which we are living in now, soils are formed,” says Dr TimarGabor. “During a glacial period, loess is deposited.” These are important considerations in terms of our understanding of the global
the development of climate models, an issue of which Dr Timar-Gabor is well aware. “The wider picture in research is that dust is an important factor in climate models, which is a major motivation behind looking at palaeoclimate sequences,” she acknowledges. “However, the main goal of the project at the moment is developing better dating methods, that’s the core of the project.”
We have been working on dating the loess-palaeosol deposits in Eastern Europe for some time. Now we will extend our work and date loess-palaeosol deposits in China, Europe, and the US climate, as dust has a significant influence on climate. For example, dust concentrations in the atmosphere affect the radiative balance of the earth, while Dr Timar-Gabor says there are also other factors to consider. “Accumulations of dust with a certain grain size can lead to the creation of nucleation centres, then more clouds and cooling. We know that historically during cold periods, we had two times more dust available than now – so dust is definitely an important factor in climate,” she explains. Dust is a correspondingly important consideration in
Alternating loess-palaeoosol deposits that reflect the Pleistocene/Holocene transition at Enders site, Nebraska.
INTERTRAP project This goal has been identified in recognition of the relative limitations of current dating methods. While optically stimulated luminescence dating methods are effective in dating some loess samples up to a certain point, inaccuracies have been identified when they have been applied on samples over around 40,000 years of age (40 ka). “We’ve shown that the results are not as accurate as we previously thought they were,” says Dr Timar-Gabor. The core of the project centers around combining more of the available dating methods in a new protocol, in order to identify why results from luminescence dating on these older samples are inaccurate. “We have the right chronology up to 40 ka – but then, for some reason, we don’t get the right results. In INTERTRAP, we use both luminescence methods as well as electron spin resonance for dating. By using the latter method we hope to improve our understanding of the mechanisms of optically stimulated luminescence production in quartz.”
Baicaoyuan: The “Sea of Loess” from the Chinese Loess Plateau. It comprises the most extensive and continuous archives of the Quaternary (~ the last 2.58 Million years) climate changes.
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