Volume 28 (2007): Issue -1 (December 2007)

We report on our first investigations into the potential of optical dating for determining the rate of river flood sedimentation in the Ardenne region (S Belgium). Two samples collected from a recent alluvial deposit were used to investigate the extent of resetting in different particle size fractions of quartz (4-11 μm, 63-90 μm, 90-125 μm, 125-180 μm, 180-212 μm and 212-250 μm) as well as in polymineral fine (4-11 μm) grains. Both samples show satisfactory OSL and IRSL characteristics. The IRSL signals from the polymineral fine grains yield an equivalent dose (D_e) of 3-4 Gy, while a D_e of 0.3-0.6 Gy was measured using large aliquots of quartz. Small aliquot analyses of 63-90 μm and 212-250 μm quartz grains confirm that the coarser fraction contains more grains with lower D_e's. Furthermore, for a modern sample (< 3 years old), ~60% of the aliquots yields a D_e consistent with zero, indicating that these contain only well-bleached grains. These findings suggest that it might be possible to extract the true burial dose from dose distributions measured using small aliquots of coarse-grained (e.g. 212-250 μm) quartz.

Luminescence dating was applied to four Neolithic pottery fragments excavated at Lumea Nouă (Alba Iulia, Romania), with the purpose of improving the chronology for the archaeological finds, and hence, the occupational history of the site. The single-aliquot regenerative-dose (SAR) protocol was applied to both blue and infrared stimulated luminescence signals from coarse quartz and polymineral fine grains, respectively. A more conventional approach which uses a multiple-aliquot additive-dose protocol and thermoluminescence signals from polymineral fine grains was applied as well.

The characteristics of the OSL and IRSL signals were investigated in terms of behaviour in the SAR protocol, dose response and dose recovery. Additionally, anomalous fading measurements of the 410 nm IRSL emission and of the blue TL emission from polymineral fine-grains were performed. Both signals were observed to be affected by anomalous fading. OSL dating of quartz using the SAR protocol is considered to be the technique of choice; it yields an average age of 6.0±0.4 ka (n = 4), which is in agreement with archaeological expectations. The dating results allow refining the typological interpretation of the objects and improve the chronological framework for the site.

The study of the evolution of the river network in the Great Hungarian Plain has been based on sedimentological, neotectonical, morphological investigations, heavy mineral analysis and complementary OSL dating. The study area extends from the Körös sub-basin into the Ér and Berettyó river valleys which are situated northeast from the subsiding basin and northwest from the uplifting Apuseni Mountains.

The OSL ages provide evidence that a large river run in the Ér-valley at least from 46±4 to 39±4 ka. It deposited garnet and magnetite-ilmenite-rich sediments, similar to the recent Berettyó, Ér and Sebes- Körös rivers and less intensive the modern Tisza river. These sediments originated from the nearly located metamorphic and Neogene volcanic rocks and contain some reworked older clastic sedimentary rocks from the northern part of the Apuseni Mountains. These OSL ages fit the active tectonic phase of the Érmellék depression. Loess is 49-47, 44, 39 and 25 ka old and aeolian sands 10 to 9 ka were dated. Their heavy mineral composition and that of fluvial sands is similar.

The TL dating of sinter crust of Morasko meteorites proves that the extraterrestrial matter fell about 5000 yr BP. Similar data were obtained for the Kaali impact. The OSL analyses show incomplete bleaching of old rock material especially in the Estonian craters. Almost all data obtained for the immediate impact area indicate ages younger than the Quaternary morphogenesis. The method used seems promising for determining the age of impacts and the origin of small depressions of unknown genesis.

The results of ¹⁴C measurements in the annual tree rings from the Ignalina Nuclear Power Plant (INPP) vicinity, Lithuania, for the period of its operation from 1984 to 2002 are presented. The terrestrial samples, mainly moss and related topsoil, are studied in places as well. The tree rings have shown the slightly enhanced ¹⁴C activity due to operation of the nuclear power plant. The maximal calculated normalized ¹⁴C release of 11 TBq/GW_e/year and the maximal effective dose of 2.0x10^-3 mSv/year resulting from the ¹⁴C were estimated for 1999. The excess of ¹⁴C specific activity measured in the moss and soil samples from moss-covered sites near the nuclear power plant (up to 0.5 km) showed highly elevated ¹⁴C contents (up to 813 pMC), probably indicating releases of the particulate material.

The paper deals with the black coloured laminae which occur within speleothems in Domica cave (Slovakia). The laminae are composed of non completely carbonized organic compounds and charcoal particles. The components were formed during combustion of plant material, mainly wood, inside the cave. Thus, they are a by-product of human activity inside the cave. The radiocarbon ages of organic fraction of these laminae fall between 6460 and 6640 cal BP and 7160 and 7330 cal BP. These dates indicate that the origin of the laminae is connected with two episodes of prehistoric occupation of the cave. The first one should be related either to later part of Gemer Linear Pottery or to early Bükk culture populations. The second episode refers to the youngest phase of human occupation in Domica cave reflecting the last period of Bükk populations' existence in the Slovak Karst.

Zoogenic deposits are one of the most important sources of the information on the history of arid ecosystems. Different organic materials form the deposit thus offering an opportunity for palaeobotanic analysis as well as for radiocarbon dating. However, many obstacles arise while dating zoogenic deposits. Some layers can be readily dated by radiocarbon as dung layers, but some of them do not contain any organic material preserved.

Three zoogenic deposits from the central part of the Negev Desert (Israel) were investigated. Azmaut deposit was accumulated more then 5000 years. This deposit is a key object of this research. The Ramon I deposit was accumulated for the last 8000 years.

The observed coincidence of the changes of the deposits and the pollen spectra testifies the presence of common causes driving them. It allows us to compare the spectrum of sufficiently dated Azmaut deposit with that of the poorly dated Bsor one. The bottom layers of the Ramon I deposit were formed 2000 years earlier than that of Azmaut. Combining the results of the pollen analysis and the radiocarbon dating of the three deposits enables us to reconstruct the vegetation history of the region during the last 8000 years.

The River Rega valley near Łobez was formed by a rapid icesheet degradation. Evolution of valleys of rivers (including the Rega) discharging into the Baltic Sea began in late Plenivistulian; it was then that glacifluvial outwash levels and kame terraces were formed. At that time, the water was flowing southward and further on towards the south-west, in a broad channel. That period was terminated at the turn of Plenivistulian and late Vistulian, when the discharge became directed northwards. The net result was the onset of the formation of the modern Rega valley system, buried chunks of dead ice still in the process of melting. Dead ice melt-down proceeded at the fastest rate during Allerød. It was then that deposits of organic matter were formed, the deposits being most probably remnants of fossil soil. Plant macro-fossils and remains of freshwater malacofauna point to a sporadic occurrence of sediments of a shallow water body which existed on the melt-down site of a huge chunk of dead ice. The thickness of the overlaying mineral cover (up to 6 m) is indicative of a fast sediment accretion rate. Sandy and silty sediments were deposited in synchrony with the dead ice melting. As a result, today's Rega valley features traces of small melt-water lakes as well as fossil sedimentation basins (underlain by the Allerød organic level), rapidly filled with fluvial and fluviolimnic sediments. Since the Preboreal, the Rega has been flowing along a meandering channel.

Large part of slope sediments (pediment) which are the effect of water induced soil erosion in the loess areas of Polish Uplands, has a close relationship with pre-historical, historical and "present" agricultural activity. The sediments accumulated in different periods are often separated by fossil soils. These soils are correlated with the periods of relinquishment of agricultural land use in a given area. A precise dating of the cycles of fossil soil formation is practically impossible. Therefore it is important to gain a possibility to establish the age of sediments between old fossil soils corresponding with the phases of soil erosion. The organic material in the floor or roof of deposits permitting a ¹⁴C dating is very seldom. This is why attempts were made to use the OSL method to date mineral parts of slope sediments. In connection with pedological and sedimentological methods, the OSL method makes it possible to give some information about the age of pre-historical and historical phases of intensive soil erosion. In order to date sediments accumulated during the last 50 years, the method based on measurement of ¹³⁷Cs isotope in products of soil erosion is used. This paper shows some examples of the application of ¹⁴C, OSL and ¹³⁷Cs methods in some selected research sites. In each case there is a discussion of limitations of the methods used.

During 2003-2006 summer excavation seasons of the Ust-Voykar settlement (65°40' N, 64°30' E) located in northwestern Siberia on the left bank of Gornaya Ob river, 121 samples of larch were collected. Living trees collected nearby were used to cross-date settlement construction. On the basis of living larch trees a 446 year (1554-1999) chronology has been constructed. Calendar dates for 101 samples of archaeological wood were established by cross-dating. Together, the living and archeological material result in a 903 year long chronology. This chronology shows similar variations as the Yamal and Polar Ural chronologies and provides new material that can be included in future climatic reconstructions.