Anja Zander

Loess chronology of the Last Interglacial/Glacial cycle in Bohemia and Moravia, Czech Republic

Abstract Combined infrared and green light stimulated luminescence and thermoluminescence dating applied to the extensively studied Bohemian and Moravian loess/palaeosol sequences from Sedlec Suchdol, Kutna Hora, Dolni Věstonice, Lechovice, Modřice, Bulhary and Cervený Kopec provides a reliable chronological framework for the last interglacial/glacial cycle. Based on this luminescence dating study a new chronology is proposed for the last interglacial/glacial loess/palaeosol sequences from the Czech Republic. IRSL and TL dating suggests that the Bt horizon of a truncated brown forest soil (lower PK III) formed during the Last Interglacial, equivalent to Oxygen Isotope Substage 5e. The upper chernozem of PKII belongs to oxygen isotope stage 3, if the combined IRSL and TL age estimates are taken into account, although from geological estimates an age range within OI Substage 5a is most likely. The Upper Weichselian loess accumulated at a very high rate. Owing to the high accumulation rate there is no time difference in sedimentation ages between the tundra gley palaeosols above PK I, which include the Upper Weichselian sediments in Central Europe.

Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-16 ka

We present a high-resolution and independently dated multiproxy lake sediment record from the paleolake at Les Echets in southeastern France that displays synchronous changes in independent limnic and terrestrial ecosystem proxies, in concert with millennial-scale climate oscillations during the last glacial period. Distinct lake-level fluctuations, low lake organic productivity, and open, treeless vegetation indicate cold and dry conditions in response to Heinrich events. Alternating phases of higher and low lake organic productivity, stratified surface waters and long-lasting lake ice cover, decreased or increased catchment erosion, and tree-dominated or herb-dominated vegetation resemble Dansgaard-Oeschger interstadialstadial variability. Transitions between different ecological states occurred in as little as 40–230 yr and seem to have been controlled by the position of the Polar Front. Ecosystem response after 30 ka suggests that local climate conditions became more important. Our results demonstrate that all parts of the terrestrial system responded to the abrupt and dramatic climatic changes associated with Dansgaard-Oeschger and Heinrich events, and that regional factors modulated ecosystem response.

Rapid coastal subsidence in the central Ganges-Brahmaputra Delta (Bangladesh) since the 17th century deduced from submerged salt-producing kilns

The densely populated, low-lying Ganges-Brahmaputra Delta is highly vulnerable to global sea-level rise. In order to estimate the rate of subsidence of the delta, we examined submerged salt-producing kiln sites in the coastal Sundarbans (a huge UNESCO-protected mangrove forest). These kilns were built just above the winterly spring high-tide level of the time, but their bases are currently located ∼155 cm below the corresponding modern level. According to optically stimulated luminescence (OSL) dating, the kilns were last fired ∼300 yr ago, and salt production was terminated by a catastrophic event that affected the kiln sites at different levels and locations. 14 C ages of charcoal at the kilns’ bases and associated mangrove stump horizons support the OSL dates. Based on the elevations and ages, the 300 yr average rate of sinking of the outer delta is 5.2 ± 1.2 mm/yr, which includes 0.8 mm/yr of eustatic sea-level rise. With the expectation of further acceleration of sea-level rise, the already-present problematic situation will be aggravated, and only prudent control of sediment accretion will keep southern Bangladesh above sea level.

Middle Pleistocene Ostracoda from a large freshwater lake in the presently dry Qaidam Basin (NW China)

Ostracods of Middle Pleistocene age were recovered from an escarpment at the northeastern margin of the large Qarhan playa surface in the Qaidam Basin (NW China). The Middle Pleistocene age of the sampled Quan Ji section was determined by means of Optically Stimulated Luminescence (OSL) dating of seven sediment samples. Among the 31 ostracod taxa identified in total, only Eucypris gyirongensis, Leucocythere dorsotuberosa and Prionocypris gansenensis seem to be restricted to high-altitude sites in Central Asia whereas most taxa are known from a number of European and Siberian (Palaeoarctic) or even Holarctic sites. Laterally widespread sediments and the ostracods from the Quan Ji section suggest the formation of a large freshwater to oligohaline lake of at least several metres in depth in the Qaidam Basin, which is presently dry apart from a few shallow salt lakes.

Multiple and single aliquot luminescence dating techniques applied to quartz extracted from Middle and Upper Weichselian loess, Zemechy, Czech Republic

This paper reports the application of optically stimulated luminescence (OSL) dating to relatively coarse grains (100–200 μm) of quartz extracted from loess. Two approaches were tested – a multiple aliquot technique and a new single aliquot approach, which is especially suited to the dating of small quantities of such grains found in some loess. The results are compared with infra-red stimulated luminescence and thermoluminescence (TL) measurements on the finer-grained (4–11 μm) polymineral fraction and TL measurements on the relatively coarse grains of quartz. The advantages of the new single aliquot (OSL) approach are described and the iterating, computer-controlled measurement procedure is given. The automated iterative single aliquot regeneration (AISAR) method corrects for changes in luminescence sensitivity during the measurement sequence by monitoring the response to a test dose. Some initial measurements are presented for the loess section at Zemechy, Czech Republic, and these show that the AISAR method gives more precise results than those using a multiple aliquot method. Copyright

Dealul Guran: evidence for Lower Palaeolithic (MIS 11) occupation of the Lower Danube loess steppe

Owing to a thick blanket of loess and other later geological disruptions, the earliest hominins to reach Europe are hard to find. To a handful of possible sites, our authors add a new assemblage of lithics with a clear local context and corroborated OSL ages. Ancient humans were present in what is now Romania between 300 000 and 400 000 years ago.