(MIS3 & 2) millennial oscillations in Greenland dust and Eurasian aeolian records – A paleosol perspective
Since their discovery, the abrupt climate changes that punctuated the last glacial period (∼110.6–14.62 ka) have attracted considerable attention. Originating in the North-Atlantic area, these abrupt changes have been recorded in ice, marine and terrestrial records all over the world, but especially in the Northern Hemisphere, with various environmental implications. Ice-core records of unprecedented temporal resolution from northern Greenland allow to specify the timing of these abrupt changes, which are associated with sudden temperature increases in Greenland over a few decades, very precisely. The continental records have, so far, been mainly interpreted in terms of temperature, precipitation or vegetation changes between the relatively warm “Greenland Interstadials” (GI) and the cooler “Greenland Stadials” (GS). Here we compare records from Greenland ice and northwestern European eolian deposits in order to establish a link between GI and the soil development in European mid-latitudes, as recorded in loess sequences. For the different types of observed paleosols, we use the correlation with the Greenland records to propose estimates of the maximum time lapses needed to achieve the different degrees of maturation and development. To identify these time lapses more precisely, we compare two independent ice-core records: δ¹⁸O and dust concentration, indicating variations of atmospheric temperature and dustiness in the Greenland area, respectively. Our method slightly differs from the definition of a GI event duration applied in other studies, where the sharp end of the δ¹⁸O decrease alone defines the end of a GI. We apply the same methodology to both records (i.e., the GIs are defined to last from the beginning of the abrupt δ¹⁸O increase or dust concentration decrease until the time when δ¹⁸O or dust recur to their initial value before the GI onset), determined both visually and algorithmically, and compare them to published estimates of GI timing and duration. The duration of the GI and consequently the maximum time for paleosol development varies between 200 and 4200 years when visually determined and between 200 and 4800 years when estimated algorithmically for GI 17 to 2, i.e. an interval running from 60 ka to 23 ka b2k (age before 2000 AD). Furthermore, we investigate the abruptness of the transition from stadial to interstadial conditions, which initiates the paleosol development. The average transition duration is 55.4 ± 16.1 (56.8 ± 19.6) years when determined visually, and 36.4 ± 13.4 (60.00 ± 21.2) years when determined algorithmically for the δ¹⁸O (dust concentration). The δ¹⁸O increases correspond to a mean temperature difference of 11.8 °C on the top of the Greenland ice sheet, associated with substantial reorganizations of the ecosystems in mid-latitude Europe.
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- Quaternary Science Reviews