TL Ages Research Articles

Paleoenvironmental interpretation of multiple soil–loess sequence at Milford Reservoir, northeastern Kansas

Abstract A loess/soil section near the Republican River in northeastern Kansas includes three superposed soils/paleosols in at least three superposed loess units, including Peoria Loess (PL), the Gilman Canyon Formation (GCF), and Loveland Loess (LL), The GCF coincides with a composite soil with a 1.3 m thick, buried organic-rich (A) horizon that yields AMS radiocarbon ages from 30.3 to 22.4 ka (or 35.7 to 26.9 ka when calibrated) that overlies a 1.6 m oxidized B horizon complex. The B subhorizons stratigraphically and morphologically resemble the “reddish pedocomplex” described elsewhere in Kansas and Illinois that dates between about 69 and 35 ka. The upper LL yields a TL age of about 136 and 130 + 30 ka. Thus, PL, the GCF, and LL were probably deposited mainly during the late Wisconsinan, middle Wisconsinan, and Illinoian (∼ Oxygen Isotope Stages (OIS) 2, 3, and 6, or about 12 to 24, 24 to 60, and 130 to 188 ka, respectively). Soils 1, 2, and 3, then formed mainly during OIS stages 1, 3, and 5, respectively, or about 12 to 12, 60 to 60, and 73 to 130 ka. In comparison with other dated stratigraphic sections in the Great Plains, soils/paleosols have relatively simple, cumulic horizon sequences, as is typical at sites distal from principle loess source regions. Nonetheless, they record a complex pedosedimentary history that reflects climatically-driven variations in rates of sedimentation and pedogenesis. Soil 1 is an Udic Argiustoll with 21-cm A (mollic)/69-cm Bt (argillic)/60-cm Bk horizons, that formed under modern-type grassland and climate. Soil 3, the Sangamon paleosol, includes a 3-m thick, highly rubified and clay-rich argillic horizon that, based on its morphological properties, probably formed under a relatively warm, moist, equable climate and deciduous-type forest. Soil 2 coincides with the GCF, and as such is a pedolithostratigraphic unit that includes a 1.3-m mollic horizon and to 1.6-m oxidized 3Btb and 3BCb horizons. Whereas the oxidized B horizons apparently represent relatively warm, moist climatic conditions between about 65 to 35 ka, the upper cumulic (mollic) A horizons of the GCF probably formed under progressively cooling climate and grassland between about 35.7 and 26.9 (calibrated radiocarbon) ka. Estimated mean accumulation rates (MARs) of loess range from 0.12 m/k yr for the GCF to about 0.5 m/k yr for PL.

Advantages and limitations of thermoluminescence dating of heated flint from Paleolithic sites

AbstractThermoluminescence (TL) dating is now widely used in the age determination of Paleolithic sites. Although the basic principle of TL‐dating is simple, the underlying assumptions are not trivial. One major source of error is the external dose rate, which contributes to a varying degree to the denominator of the age formula and thus has a varying influence on the dating result. The intention of this paper is to enable the user to evaluate TL age determinations of heated flint. The parameters used for age determination and some of their relationships are discussed. It is shown that the reliability of TL results of heated flint depends on the proportion of the various dose‐rate parameters and that these are important for the evaluation of ages. The limitations of the method as well as the advantages are discussed. TL‐dating results for two Near Eastern Paleolithic sites (Rosh Ein Mor and Jerf al‐Ajla) are discussed as examples. © 2007 Wiley Periodicals, Inc.

TL Ages of Loesses from the Last Two Glacials in Se Poland

TL Ages of Loesses from the Last Two Glacials in Se Poland Loesses cover a large area in SE Poland so their exploration is an important part of the palaeogeographical studies on Pleistocene. The research involves stratigraphic problems. At present, luminescence dating provides the greatest number of chronostratigraphic data concerning loesses. In this work we report TL ages of loesses from the last two glacial cycles in SE Poland, obtained in the TL Laboratory of the Department of Physical Geography and Palaeogeography, Maria Curie-Skłodowska University in Lublin after 1993. Samples for TL dating were collected in 11 loess profiles (2-9 samples in each site) in order to obtain additional information for stratigraphic interpretations deduced from paleopedological, lithological, structural, and other data. Basing on the comparison of 54 TL ages, we can determine age intervals, in which the dating results of similar values assemble, and then get general information about the periods of intensified Aeolian accumulation related to defined stratigraphic units. The TL ages of all samples were obtained using the total-bleach method (TB) for the determination of the equivalent dose.

Hayonim Cave: a TL-based chronology for this Levantine Mousterian sequence

The thermoluminescence dating method was applied to 77 heated flints from the Mousterian layers of Hayonim Cave in order to provide a precise TL-based chronology for this important Levantine sequence. A detailed dosimetric study was performed by using 76 dosimeter capsules and revealed strong spatial dose-rate variations. In parallel, Fourier transform infrared spectrometry enabled the identification of various mineral assemblages in the sediments of the cave and to localize the boundaries of these assemblages. By comparing these two data sets, it is shown that low dose-rate values (∼500 μGy/a) are systematically recorded in areas where the calcite-dahllite (CD) assemblage is preserved, whereas higher values (up to 1300 μGy/a) are associated with the leucophosphite, montgomeryite, variscite and siliceous aggregates (LMVS) assemblage. The dosimetric and mineralogical information was combined in order to assess, where possible, the dose-rate experienced by each flint during its burial. Some of the flint samples analyzed were too close to mineral assemblage boundaries and were therefore discarded. This rigorous selection led to TL ages ranging from 230 to 140 ka for the lower part of the Mousterian sequence (layers F and Lower E), which contains lithic industries characterized by blade production using the laminar method.

Trans-arctic-ocean tests of fine-silt luminescence sediment dating provide a basis for an additional geochronometer for this region

New geochronometers are needed for sediments of the Arctic Ocean spanning at least the last half million years, largely because oxygen-isotope stratigraphy is relatively ineffective in this ocean, and because other dating techniques require significant assumptions about sedimentation rates. Multi-aliquot luminescence sediment-dating procedures were applied to polymineral, fine-silt samples from 9 core-top and 37 deeper samples from 20 cores representing 19 sites across the Arctic Ocean. Most samples have independent age assignments and other known properties (e.g., % coarse fraction, % carbonate, U-Th isotopes). Thick-source alpha-particle counting indicates that for most regions the contribution of measured unsupported 230Th and 231Pa to calculated dose rates is <ca+5–11%. IR-PSL dating of polymineral fine-silt fractions from core-top and near-core-top samples indicates that three sites (mainly from the western Arctic Ocean) have long-bleach inherited ages of only 3–7 kyr, suggesting potential for accurate PSL and TL dating without an inherited correction when older interglacial samples are selected. Samples from a giant gravity core from the western region (Northwind Ridge) yield acceptable long-bleach TL and IR-PSL ages up to 100 kyr. A sample from the eastern region (near Gakkel Ridge) gives a long-bleach age of ca 60 kyr, agreeing with an independent age assignment. Several samples in the 10–40 kyr 14C range from other sites produce large long-bleach age overestimates, indicating the variable effects of ice-rafting and other depositional and bottom-current-reworking (re-suspension) processes during glacial stages. Short-bleach dating tests provide IR-PSL age estimates for core tops that appear to penetrate the ‘reworking veil’ of inherited ages, and not only suggest a procedure to greatly reduce long-bleach inherited ages but also have implications for the 14C reservoir correction. This study identifies the most promising regions for future luminescence dating, and suggests that for several regions of the Arctic Ocean, interglacial-stage (foram-‘rich’) sediments from ridge tops are preferred for the fine-grain luminescence dating methods.

Dilemma of Dating on Lacustrine Deposits in an Hyperarid Inland Basin of NW China

Conventional and accelerator mass spectrometry (AMS) radiocarbon, TL, OSL, and IRSL dating results on samples from the cores D100 and I70 from Ejina Basin, one of the most important inland basins in arid-hyperarid NW China, show that it is difficult to determine the ages of sediments at different depths. AMS ages of core D100 samples demonstrate that the sediments at depths from 10 to 90 m were formed between 14 to 30 kyr BP. The inverted ages from both the D100 and I70 cores imply that there was a strong reworking of the sediments during and after deposition processes. The inverted ages also indicate drastic fluctuations of groundwater bearing soluble organic matters, which might be related to neotectonic activities and climate changes during the period. Consequently, it is impossible to establish an accurate and reliable chronology for the cores based only on these dates. All AMS ages, if they are reliable and acceptable, indicate a high deposition rate (5∼8 mm/yr), and since all TL, OSL, and IRSL ages are much older than those given by AMS, it makes these methods questionable for determining the ages of lacustrine-fluvial-alluvial deposits.

Reproductive biology of racer goby Neogobius gymnotrachelus in the Wloclawski Reservoir (Vistula River, Poland)

Summary Initial studies on the reproductive parameters and spawning behaviour of racer goby Neogobius gymnotrachelus, one of three Ponto-Caspian gobiid species recently invading Polish waters, were carried out in Wloclawski Reservoir (lower River Vistula, Poland), where spawning lasted from April to August. Males were on average about 23.3% longer and 53.8% heavier than females. The smallest female with mature gonads was 58 mm TL (estimated age 2+ years), and males were sexually mature at 59 mm TL (age of 1+ years). Gonado-somatic index at the beginning of spawning was seven times larger in females (mean = 8.4) than that in males (mean = 1.2). Mean absolute fecundity was 952 eggs per female (361–2236). Egg diameter ranged from 0.140 to 1.558 mm, being of bi-modal distribution, which suggests two or three spawning bouts. Length–frequency analysis of juveniles revealed a multimodal distribution. Specialized reproductive behaviour (nest construction and parental care of eggs) and an extended spawning period increase the probability that racer goby can successfully establish self-sustaining populations in novel environments.

U-series and ESR analyses of bones and teeth relating to the human burials from Skhul

In order to resolve long-standing issues surrounding the age of the Skhul early modern humans, new analyses have been conducted, including the dating of four well-provenanced fossils by ESR and U-series. If the Skhul burials took place within a relatively short time span, then the best age estimate lies between 100 and 135 ka. This result agrees very well with TL ages obtained from burnt flint of 119±18 ka (Mercier et al., 1993). However, we cannot exclude the possibility that the material associated with the Skhul IX burial is older than those of Skhul II and Skhul V. These and other recent age estimates suggest that the three burial sites, Skhul, Qafzeh and Tabun are broadly contemporaneous, falling within the time range of 100 to 130 ka. The presence of early representatives of both early modern humans and Neanderthals in the Levant during Marine Isotope Stage 5 inevitably complicates attempts at segregating these populations by date or archaeological association. Nevertheless, it does appear that the oldest known symbolic burials are those of early modern humans at Skhul and Qafzeh. This supports the view that, despite the associated Middle Palaeolithic technology, elements of modern human behaviour were represented at Skhul and Qafzeh prior to 100 ka.

Numerical chronology of Pleistocene coastal plain and valley development; extensive aggradation during glacial low sea-levels

Based on more than 60 newly acquired luminescence ages, field information, and sediment granulometry data, a comprehensive chronostratigraphic framework is presented for Pleistocene alluvial coastal plain and valley terraces and coastal barrier trends on the northern Gulf of Mexico between Texas and NW Florida. Luminescence ages 216–188 ka from the second youngest coastal terrace coincide with the highstand during the second youngest Pleistocene Marine Isotope Stage (MIS 7a). TL ages from the oldest Prairie alluvium and OSL-ages from the Gulfport barriers; 124–116 ka, are consistent with the Sangamon interglacial substage, MIS 5e. Forest assemblages of the last two Pleistocene highstands are very similar to the present hard pine-dominated arboreal flora, established under warm-temperate, humid conditions. Ages of the youngest, Prairie–Beaumont coastal terrace overlap with the Eowisconsin (MIS 5d–5a) and Wisconsin (MIS 4 and 3) stages, associated with a sea-level range of −80 to −30 m. Coastal plain aggradation, not limited to interglacial highstands occurred during the much longer preglacial and glacial low sea-level stages. The Prairie–Beaumont coastal plain is a collage of seamlessly merged surfaces, aggraded between ca.135 and 30 ka in several alluviation stages. Periodically dry conditions, associated with enhanced slope erosion and consequent increase in sheetwash, colluvial, and fluvial sediment flux may have induced substantial aggradation at significant distances inland from the coeval shorelines during depressed preglacial and glacial sea-levels. This balance between erosion and sediment delivery may explain the diminished control of lower Eowisconsin and Wisconsin sea-levels (base-levels) on coastal entrenchment and aggradation. The combined effects of alluvial aggradation and subsequent uplift, modified by surface erosion produced the present coastal plain topography. An early post-Sangamon phase of deep entrenchment involved the Amite, Sabine, Neches, and the Pearl Valleys in Eowisconsin and early Wisconsin times. Except for the universal impact of the deep Last Glacial Maximum (LGM) entrenchment, the alluviation–incision cycles that produced two to four sets of terraces of aggradational and strath origin did not occur in all valleys synchronously and with identical effects. In certain valleys terrace aggradation coincided with the LGM record lowstand and the following late Wisconsin transgressive deglacial hemicycle. In contrast with intensive valley filling, inferred for the MIS 6 glacial interval, Holocene backfilling is far from complete in most late glacial entrenched valleys.

Late Pleistocene glaciation of the Hulifang Massif of Gongwang mountains in Yunnan Province

Late Pleistocene glaciation was restricted to only a few high mountains in eastern China. The Gongwang mountains constitute one of the typical places once glaciated. Geomorphic mapping of the area and the TL dating provides evidence for at least four distinct glaciations. YJT-I glacial advance occurred about 100 ka BP and two TL absolute ages (101,100 ± 7780 a BP; 104,000 ± 8300 a BP) indicate this advance happened during the Penultimate Glaciation. The early stage glacial advance (YJT-II advance) during the last glaciation occurred about 40,920 ± 3400 a BP. The last glacial maximum advance (YJT-III advance) about 18–25 ka BP, which sustained by two TL ages (18,230 ±1420 a BP; 25,420 ± 2110 a BP). The Penultimate and the early stage glaciations were more extensive and the last glacial maximum (LGM) and the late-glacial period (YJT-IV advance, 10 ka BP) were progressively less extensive. Correlated with the other mountains in eastern China, these glacial advances in the Gongwang mountains just like the advances in the western part such as Diancang mountains, Yulong mountains of Yunnan Province and the glacier series are more complete than the adjacent mid-latitude regions such as Taibai mountain and Taiwan mountains and are roughly representative of climate changes during the last glacial cycle in Yunnan Province.

Effects of thermal treatment on TL and EPR of flints and their importance in TL-dating: application to French Mousterian sites of Les Forêts (Dordogne) and Jiboui (Drôme)

This study of trapped charge phenomena in flint highlights the influence of laboratory thermal annealing conditions on TL properties and age evaluation. The effectiveness of thermal zeroing of geological, or weakly heated flint, is investigated by EPR and TL; the 380 °C TL peak (correlated to the Al centre) is totally erased after heating at 300 °C for 20 min and the 470 °C TL component (OHC centre) after heating at 400 °C for 20 min. We attempt to determine laboratory conditions of annealing that lead to a state of trap distribution and charge filling that is closest to that the archaeological material had after its ancient firing. Under these conditions, the original mode of TL growth with dose is expected to be more appropriate; consequently, more reliable TL ages should be obtained using the standard TL protocol. The way to determine appropriate annealing conditions is the result of a coupled TL–EPR study: EPR characterisation of organic radicals and evolution of the E ′ centre according to Toyoda et al.'s protocol (1993) together with the evolution of regenerated glow curve shapes and TL sensitivity with the thermal treatment. As an illustration, the following TL ages have been obtained with the assistance of EPR, on Mousterian flints from two French open air sites. The age of the Mousterian occupation at Les Forêts (Dordogne) 92.7 ± 4.5 ka , which fits into the palaeoenvironmental chronological frame, provides accurate information for archaeologists. The site of Les Forêts was the first open air Mousterian site found in south-west of France thanks to rescue excavations, in a region where cave and rock shelter sites essentially are known. The age of the Mousterian occupation at Jiboui Path (in the Alps, Drôme), 52.0 ± 2.6 ka , is consistent with possible seasonal occupation of altitude sites during warmer phases of the last Glacial period. As data for alpine area are rare, dating this type of site was of fundamental interest for the study of the (pre)history of populations.

DATING ARCHAEOMETALLURGICAL SLAGS USING THERMOLUMINESCENCE*

Thermoluminescence has a great potential for dating archaeometallurgical slags, because the smelting process leads to a well‐defined resetting of the ‘luminescence clock’. However, the complex compositions of slags have unpleasant consequences for TL measurements if the bulk slag substance is used. To overcome this problem, quartz has been separated out of slag matrices by chemical and physical procedures. The TL measurements were carried out on this defined mineral phase. This method was tested with seven slag samples from different locations and ages. In most cases, the TL ages determined show good agreement with reference data.

Confirmation of a near 400 ka age for the Yabrudian industry at Tabun Cave, Israel

The important Lower and Middle Palaeolithic site of Tabun has been previously dated using ESR, U-series and TL. ESR ages throughout the site are substantially younger than TL dates, although these methods have been shown to agree at other sites in Israel and elsewhere. All previous ESR dates have been obtained on museum specimens using only attached sediments for dosimetry. Here we report the first ESR and U-series analyses of a tooth found in situ in an area equivalent to the lowest part of layer Ed. We obtain a combined ESR/U-series age of 387 +49 −36ka, in good agreement with a TL age of 340±33 ka for similar levels, and substantially older than an ESR/U-series age using attached or nearby sediment for dosimetry. We conclude that the most likely explanation for the previous shorter ESR chronology was the use of inappropriate gamma dose rates based on sediments attached to teeth.

The Last Interglacial palaeosol in the Belgian loess belt: TL age record

In the Belgian loess plateau, the Rocourt soil is a well-known luvisol horizon that is regarded as representing the Last Interglacial. The name of the soil comes from the locality of Rocourt in the east of the country, where it has been observed for the first time. Later, exposures of a similar soil were found in other localities. Most typically, a sequence of three horizons is observed: a red-brown illuvial Bt horizon, overlain by a bleached horizon and a compound dark horizon. In this paper, we present the results of TL age determinations obtained on sediments directly bracketing the soil at the type locality of Rocourt and at the locality of Momalle more to the west, together with some supplementary data for the exposures at Kesselt to check a controversial result that was obtained earlier (J. Quaternary Sci. 13 (5) (1998) 487). The TL analyses involved both the (total bleach) additive dose and regeneration methods. Our TL ages confirm the assumed chronostratigraphic position (oxygen isotope stage 5) of the soil exposed at the type locality. The ages obtained at Momalle and Kesselt indicate that we are dealing with the same soil here but the palaeodose data are less consistent. This is probably due to the fact that the loess has been disturbed by post-depositional processes such as solifluction, surface run-off, cryo- and bioturbation. This seems to be a major problem with the sediments in the eastern part of the Belgian loess belt.

Quaternary calcarenite stratigraphy on Lord Howe Island, southwestern Pacific Ocean and the record of coastal carbonate deposition

Lord Howe Island is a small, mid-ocean volcanic and carbonate island in the southwestern Pacific Ocean. Skeletal carbonate eolianite and beach calcarenite on the island are divisible into two formations based on lithostratigraphy. The Searles Point Formation comprises eolianite units bounded by clay-rich paleosols. Pore-filling sparite and microsparite are the dominant cements in these eolianite units, and recrystallised grains are common. Outcrops exhibit karst features such as dolines, caves and subaerially exposed relict speleothems. The Neds Beach Formation overlies the Searles Point Formation and consists of dune and beach units bounded by weakly developed fossil soil horizons. These younger deposits are characterised by grain-contact and meniscus cements, with patchy pore-filling micrite and mirosparite. The calcarenite comprises several disparate successions that contain a record of up to 7 discrete phases of deposition. A chronology is constructed based on U/Th ages of speleothems and corals, TL ages of dune and paleosols, AMS 14C and amino acid racemization (AAR) dating of land snails and AAR whole-rock dating of eolianite. These data indicate dune units and paleosols of the Searles Point Formation were emplaced during oxygen isotope stage (OIS) 7 and earlier in the Middle Pleistocene. Beach units of the Neds Beach Formation were deposited during OIS 5e while dune units were deposited during two major phases, the first coeval with or shortly after the beach units, the second later during OIS 5 (e.g. OIS 5a) when the older dune and beach units were buried. Large-scale exposures and morphostratigraphical features indicate much of the carbonate was emplaced as transverse and climbing dunes, with the sediment source located seaward of and several metres below the present shoreline. The lateral extent and thickness of the eolianite deposits contrast markedly with the relatively small modern dunes. These features indicate that a slight fall (2–10 m) in sea level may be required to mobilise relatively large volumes of sediment onto the island. The stratigraphy of the calcarenite, combined with the shallow depth of the platform surrounding the island (30–50 m present water depth) and the geochronological data, suggest that cycles of carbonate deposition on the island are linked to interglacial and interstadial periods of high or falling sea level.

Quaternary aminostratigraphy of eolianite on Lord Howe Island, Southwest Pacific Ocean

Amino acid racemization (AAR) dating of the eolianite on Lord Howe Island is used to correlate several disparate successions and provides a geochronological framework that ranges from Holocene to Middle Pleistocene time. The reliability of the AAR data is assessed by analysing multiple samples from individual lithostratigraphic units, checking the stratigraphic order of the D/L ratios and the consistency of the relative extents of racemization for a suite of seven amino acids. Three aminozones are defined on the basis of the extent of racemization of amino acids in land snails ( Placostylus bivaricosus) and ‘whole-rock’ eolianite samples. Aminozone A includes Placostylus from modern soil horizons (e.g. mean D/L-leucine ratio of 0.03±0.01) and whole-rock samples from unconsolidated lagoonal and beach deposits (0.10±0.01–0.07±0.03). Aminozone B includes Placostylus (0.45±0.03) and whole-rock samples from beach (0.48±0.01) and dune (0.45±0.02–0.30±0.02) units of the Neds Beach Formation, deposited during OIS 5. The oldest, Aminozone C, comprises Placostylus recovered from paleosols (0.76±0.02) and whole-rock eolianite samples (0.62±0.00) from the Searles Point Formation, which indicate the formation was likely deposited over several Oxygen Isotope Stages (OIS), during and prior to OIS 7. These data support independent lithostratigraphic interpretations and are in broad agreement with U/Th ages of speleothems from the Searles Point Formation and corals from the Neds Beach Formation, and with several TL ages of dune units in both formations. The AAR data reveal that eolianite deposition extends over a significantly longer time interval than previously appreciated and indicate that the deposition of the large dune units is linked to periods of relatively high sea level.

The ion chemistry of lakes and late Holocene desiccation in the Badain Jaran Desert, Inner Mongolia, China

In the markedly arid Badain Jaran Desert, one of the least-studied areas in the world, over a hundred permanent lakes exist among the dunes. The geochemistry of water samples from nine lakes and from the groundwater in the desert and on its periphery was investigated. Ion chemistry of the water from these desert lakes changes considerably on a regional scale. We argue that there is a positive correlation between the ages of these lakes and their totally dissolved solids (TDS) varying between 1.2 and 398.2 g/l. Tritium analysis of groundwater in wells gives an age generally older than four decades and younger than 100 years. The lacustrine deposits, freshwater fauna and shorelines indicate the existence of large water bodies with low salinities in the inter-dune hollows of this desert during the early and middle Holocene. The precipitation in this desert during the early and middle Holocene was estimated to be ca. 200 mm/year on average, at least twice as high as at present. On the basis of paleoecology, TL and radiocarbon ages, it was concluded that the huge enrichment of ions in the lakes and decrease of water availability originated from climatic desiccation during the last 4000 years. The paleoclimate of the Badain Jaran Desert reported here was remarkably consistent with the late Quaternary climatic histories of the regions to the immediate north, west, east and south of the study area.

Late Pleistocene luminescence chronology of loess deposition in the Missouri and Mississippi river valleys, United States

The loess stratigraphy of the mid-continental U.S. is an important proxy record for the advance of the North American ice sheet into the catchment of the Mississippi, Missouri and Ohio rivers. One of the most outstanding problems is deciphering the age of the loess deposits in this area during the Late Pleistocene. We used multiple-aliquot additive dose procedures under infrared stimulated luminescence (IRSL) and single aliquot regeneration (SAR) protocols to resolve ages of loess at the Loveland Silt type locality, Iowa, the Pleasant Grove School section, Illinois, and the Bonfils Quarry section, Missouri. Radiocarbon dated levels in the Peoria Loess and Roxana Silt were used to test the accuracy of the IRSL and SAR methods. SAR on polymineral and quartz extracts yielded underestimates in age by 20–55%, whereas IRSL gave concordant ages to the 14C control and was used to date the loess sequences. The oldest loess, the Bonfils Silt, gave IRSL ages between 159 and 264 ka and are considered non-finite estimates because the luminescence response was near saturation with additive β dose. The Loveland Silt at the type locality exhibited considerable luminescence in growth with additive β dose and yielded the mean age of 159±14 ka (n=4). The Teneriffe Silt gave a mean IRSL age of 93±5 ka (n=4) which, overlaps at two σ with a previous TL age and indicates deposition sometime between 100 and 80 ka. The Roxana Silt yielded stratigraphically consistent IRSL ages between ca. 60 and 30 ka. Luminescence and radiocarbon dating indicate that there were four distinct periods of loess deposition in the Mississippi and Missouri river basins at ca. 180–140 ka, 100–80 ka, 60–30 ka, and 25–12 ka which are concordant with periods of meltwater input to the Gulf of Mexico, another proxy of glaciation in mid-continental North America.

Luminescence quartz dating of lime mortars. A first research approach.

Lime mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870 +/- 230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095 +/- 190 a.

Late Pleistocene invasion of Palaeo-Dead Sea into the lower Zin Valley, the Negev Highlands, Israel

Evidence of invasion of Lake Lisan, the Late Pleistocene precursor of the Dead Sea, is revealed within the valley of lower Nahal Zin that runs down to the Dead Sea from the Negev Highlands. The main proof of the invasion is presence of lacustrine sediments that are followed contin- uously along the Lower Zin valley for a distance of 25 km from the coast of the Dead Sea. Extending deep into the interior of the Nahal Zin valley, the lacustrine sediments are included in the terraces at relative heights of 16 and 28-32 m. They overlay alluvial bases of the terraces or interbed in al- luvial deposits. TL dating has demonstrated that age of the lacustrine sediments is of about 30 Ka. TL ages of the de- posits forming the alluvial bases of the terraces, which are covered by the lacustrine sediments, are of 40 to 60 Ka. Oth- erwise Pleistocene lacustrine sediments both in younger and older age are absent in the terrace sections of the Zin valley. The revealed lacustrine sediments are uppermost, known of this kind. They are tapered out at 130 m altitude, and de- posed during the highest stand of Lake Lisan, which is cor- related with the marine isotope stage 2. Other fluctuations in the level of the Dead Sea and its Pleistocene precursors also exerted an influence on the development of the Zin valley. However their evidence occurs only in the Dead Sea tectonic basin except of the deep interior of the valley.